BIG-IP Access Policy Manager (APM)

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APM Configuration to Support Duo MFA using iRule
Overview BIG-IP APM has supported Duo as an MFA provider for a long time with RADIUS-based integration. Recently, Duo has added support for Universal Prompt that uses Open ID Connect (OIDC) protocol to provide two-factor authentication. To integrate APM as an OIDC client and resource server, and Duo as an Identity Provider (IdP), Duo requires the user’s logon name and custom parameters to be sent for Authentication and Token request. This guide describes the configuration required on APM to enable Duo MFA integration using an iRule. iRules addresses the custom parameter challenges by generating the needed custom values and saving them in session variables, which the OAuth Client agent then uses to perform MFA with Duo. This integration procedure is supported on BIG-IP versions 13.1, 14.1x, 15.1x, and 16.x. To integrate Duo MFA with APM, complete the following tasks: 1. Choose deployment type: Per-request or Per-session 2. Configure credentials and policies for MFA on the DUO web portal 3. Create OAuth objects on the BIG-IP system 4. Configure the iRule 5. Create the appropriate access policy/policies on the BIG-IP system 6. Apply policy/policies and iRule to the APM virtual server Choose deployment type APM supports two different types of policies for performing authentication functions. Per-session policies: Per-session policies provide authentication and authorization functions that occur only at the beginning of a user’s session. These policies are compatible with most APM use cases such as VPN, Webtop portal, Remote Desktop, federation IdP, etc. Per-request policies: Per-request policies provide dynamic authentication and authorization functionality that may occur at any time during a user’s session, such as step-up authentication or auditing functions only for certain resources. These policies are only compatible with Identity Aware Proxy and Web Access Management use cases and cannot be used with VPN or webtop portals. This guide contains information about setting up both policy types. Prerequisites Ensure the BIG-IP system has DNS and internet connectivity to contact Duo directly for validating the user's OAuth tokens. Configure credentials and policies for MFA on Duo web portal Before you can protect your F5 BIG-IP APM Web application with Duo, you will first need to sign up for a Duo account. 1. Log in to the Duo Admin Panel and navigate to Applications. 2. Click Protect an application. Figure 1: Duo Admin Panel – Protect an Application 3. Locate the entry for F5 BIG-IP APM Web in the applications list and click Protect to get the Client ID, Client secret, and API hostname. You will need this information to configure objects on APM. Figure 2: Duo Admin Panel – F5 BIG-IP APM Web 4. As DUO is used as a secondary authentication factor, the user’s logon name is sent along with the authentication request. Depending on your security policy, you may want to pre-provision users in Duo, or you may allow them to self-provision to set their preferred authentication type when they first log on. To add users to the Duo system, navigate to the Dashboard page and click the Add New...-> Add User button. A Duo username should match the user's primary authentication username. Refer to the https://duo.com/docs/enrolling-users link for the different methods of user enrollment. Refer to Duo Universal Prompt for additional information on Duo’s two-factor authentication. Create OAuth objects on the BIG-IP system Create a JSON web key When APM is configured to act as an OAuth client or resource server, it uses JSON web keys (JWKs) to validate the JSON web tokens it receives from Duo. To create a JSON web key: 1. On the Main tab, select Access > Federation > JSON Web Token > Key Configuration. The Key Configuration screen opens. 2. To add a new key configuration, click Create. 3. In the ID and Shared Secret fields, enter the Client ID and Client Secret values respectively obtained from Duo when protecting the application. 4. In the Type list, select the cryptographic algorithm used to sign the JSON web key. Figure 3: Key Configuration screen 5. Click Save. Create a JSON web token As an OAuth client or resource server, APM validates the JSON web tokens (JWT) it receives from Duo. To create a JSON web token: 1. On the Main tab, select Access > Federation > JSON Web Token > Token Configuration. The Token Configuration screen opens. 2. To add a new token configuration, click Create. 3. In the Issuer field, enter the API hostname value obtained from Duo when protecting the application. 4. In the Signing Algorithms area, select from the Available list and populate the Allowed and Blocked lists. 5. In the Keys (JWK) area, select the previously configured JSON web key in the allowed list of keys. Figure 4: Token Configuration screen 6. Click Save. Configure Duo as an OAuth provider APM uses the OAuth provider settings to get URIs on the external OAuth authorization server for JWT web tokens. To configure an OAuth provider: 1. On the Main tab, select Access > Federation > OAuth Client / Resource Server > Provider. The Provider screen opens. 2. To add a provider, click Create. 3. In the Name field, type a name for the provider. 4. From the Type list, select Custom. 5. For Token Configuration (JWT), select a configuration from the list. 6. In the Authentication URI field, type the URI on the provider where APM should redirect the user for authentication. The hostname is the same as the API hostname in the Duo application. 7. In the Token URI field, type the URI on the provider where APM can get a token. The hostname is the same as the API hostname in the Duo application. Figure 5: OAuth Provider screen 8. Click Finished. Configure Duo server for APM The OAuth Server settings specify the OAuth provider and role that Access Policy Manager (APM) plays with that provider. It also sets the Client ID, Client Secret, and Client’s SSL certificates that APM uses to communicate with the provider. To configure a Duo server: 1. On the Main tab, select Access > Federation > OAuth Client / Resource Server > OAuth Server. The OAuth Server screen opens. 2. To add a server, click Create. 3. In the Name field, type a name for the Duo server. 4. From the Mode list, select how you want the APM to be configured. 5. From the Type list, select Custom. 6. From the OAuth Provider list, select the Duo provider. 7. From the DNS Resolver list, select a DNS resolver (or click the plus (+) icon, create a DNS resolver, and then select it). 8. In the Token Validation Interval field, type a number. In a per-request policy subroutine configured to validate the token, the subroutine repeats at this interval or the expiry time of the access token, whichever is shorter. 9. In the Client Settings area, paste the Client ID and Client secret you obtained from Duo when protecting the application. 10. From the Client's ServerSSL Profile Name, select a server SSL profile. Figure 6: OAuth Server screen 11. Click Finished. Configure an auth-redirect-request and a token-request Requests specify the HTTP method, parameters, and headers to use for the specific type of request. An auth-redirect-request tells Duo where to redirect the end-user, and a token-request accesses the authorization server for obtaining an access token. To configure an auth-redirect-request: 1. On the Main tab, select Access > Federation > OAuth Client / Resource Server > Request. The Request screen opens. 2. To add a request, click Create. 3. In the Name field, type a name for the request. 4. For the HTTP Method, select GET. 5. For the Type, select auth-redirect-request. 6. As shown in Figure 7, specify the list of GET parameters to be sent: request parameter with value depending on the type of policy For per-request policy: %{subsession.custom.jwt_duo} For per-session policy: %{session.custom.jwt_duo} client_id parameter with type client-id response_type parameter with type response-type Figure 7: Request screen with auth-redirect-request (Use “subsession.custom…” for Per-request or “session.custom…” for Per-session) 7. Click Finished. To configure a token-request: 1. On the Main tab, select Access > Federation > OAuth Client / Resource Server > Request. The Request screen opens. 2. To add a request, click Create. 3. In the Name field, type a name for the request. 4. For the HTTP Method, select POST. 5. For the Type, select token-request. 6. As shown in Figure 8, specify the list of POST parameters to be sent: client_assertion parameter with value depending on the type of policy For per-request policy: %{subsession.custom.jwt_duo_token} For per-session policy: %{session.custom.jwt_duo_token} client_assertion_type parameter with value urn:ietf:params:oauth:client-assertion-type:jwt-bearer grant_type parameter with type grant-type redirect_uri parameter with type redirect-uri Figure 8: Request screen with token-request (Use “subsession.custom…” for Per-request or “session.custom…” for Per-session) 7. Click Finished. Configure the iRule iRules gives you the ability to customize and manage your network traffic. Configure an iRule that creates the required sub-session variables and usernames for Duo integration. Note: This iRule has sections for both per-request and per-session policies and can be used for either type of deployment. To configure an iRule: 1. On the Main tab, click Local Traffic > iRules. 2. To create an iRules, click Create. 3. In the Name field, type a name for the iRule. 4. Copy the sample code given below and paste it in the Definition field. Replace the following variables with values specific to the Duo application: <Duo Client ID> in the getClientId function with Duo Application ID. <Duo API Hostname> in the createJwtToken function with API Hostname. For example, https://api-duohostname.com/oauth/v1/token. <JSON Web Key> in the getJwkName function with the configured JSON web key. Note: The iRule ID here is set as JWT_CREATE. You can rename the ID as desired. You specify this ID in the iRule Event agent in Visual Policy Editor. Note: The variables used in the below example are global, which may affect your performance. Refer to the K95240202: Understanding iRule variable scope article for further information on global variables, and determine if you use a local variable for your implementation. proc randAZazStr {len} { return [subst [string repeat {[format %c [expr {int(rand() * 26) + (rand() > .5 ? 97 : 65)}]]} $len]] } proc getClientId { return <Duo Client ID> } proc getExpiryTime { set exp [clock seconds] set exp [expr $exp + 900] return $exp } proc getJwtHeader { return "{\"alg\":\"HS512\",\"typ\":\"JWT\"}" } proc getJwkName { return <JSON Web Key> #e.g. return "/Common/duo_jwk" } proc createJwt {duo_uname} { set header [call getJwtHeader] set exp [call getExpiryTime] set client_id [call getClientId] set redirect_uri "https://" set redirect [ACCESS::session data get "session.server.network.name"] append redirect_uri $redirect append redirect_uri "/oauth/client/redirect" set payload "{\"response_type\": \"code\",\"scope\":\"openid\",\"exp\":${exp},\"client_id\":\"${client_id}\",\"redirect_uri\":\"${redirect_uri}\",\"duo_uname\":\"${duo_uname}\"}" set jwt_duo [ ACCESS::oauth sign -header $header -payload $payload -alg HS512 -key [call getJwkName] ] return $jwt_duo } proc createJwtToken { set header [call getJwtHeader] set exp [call getExpiryTime] set client_id [call getClientId] set aud "<Duo API Hostname>/oauth/v1/token" #Example: set aud https://api-duohostname.com/oauth/v1/token set jti [call randAZazStr 32] set payload "{\"sub\": \"${client_id}\",\"iss\":\"${client_id}\",\"aud\":\"${aud}\",\"exp\":${exp},\"jti\":\"${jti}\"}" set jwt_duo [ ACCESS::oauth sign -header $header -payload $payload -alg HS512 -key [call getJwkName] ] return $jwt_duo } when ACCESS_POLICY_AGENT_EVENT { set irname [ACCESS::policy agent_id] if { $irname eq "JWT_CREATE" } { set ::duo_uname [ACCESS::session data get "session.logon.last.username"] ACCESS::session data set session.custom.jwt_duo [call createJwt $::duo_uname] ACCESS::session data set session.custom.jwt_duo_token [call createJwtToken] } } when ACCESS_PER_REQUEST_AGENT_EVENT { set irname [ACCESS::perflow get perflow.irule_agent_id] if { $irname eq "JWT_CREATE" } { set ::duo_uname [ACCESS::session data get "session.logon.last.username"] ACCESS::perflow set perflow.custom [call createJwt $::duo_uname] ACCESS::perflow set perflow.scratchpad [call createJwtToken] } } Figure 9: iRule screen 5. Click Finished. Create the appropriate access policy/policies on the BIG-IP system Per-request policy Skip this section for a per-session type deployment The per-request policy is used to perform secondary authentication with Duo. Configure the access policies through the access menu, using the Visual Policy Editor. The per-request access policy must have a subroutine with an iRule Event, Variable Assign, and an OAuth Client agent that requests authorization and tokens from an OAuth server. You may use other per-request policy items such as URL branching or Client Type to call Duo only for certain target URIs. Figure 10 shows a subroutine named duosubroutine in the per-request policy that handles Duo MFA authentication. Figure 10: Per-request policy in Visual Policy Editor Configuring the iRule Event agent The iRule Event agent specifies the iRule ID to be executed for Duo integration. In the ID field, type the iRule ID as configured in the iRule. Figure 11: iRule Event agent in Visual Policy Editor Configuring the Variable Assign agent The Variable Assign agent specifies the variables for token and redirect requests and assigns a value for Duo MFA in a subroutine. This is required only for per-request type deployment. Add sub-session variables as custom variables and assign their custom Tcl expressions as shown in Figure 12. subsession.custom.jwt_duo_token = return [mcget {perflow.scratchpad}] subsession.custom.jwt_duo = return [mcget {perflow.custom}] Figure 12: Variable Assign agent in Visual Policy Editor Configuring the OAuth Client agent An OAuth Client agent requests authorization and tokens from the Duo server. Specify OAuth parameters as shown in Figure 13. In the Server list, select the Duo server to which the OAuth client directs requests. In the Authentication Redirect Request list, select the auth-redirect-request configured earlier. In the Token Request list, select the token-request configured earlier. Some deployments may not need the additional information provided by OpenID Connect. You could, in that case, disable it. Figure 13: OAuth Client agent in Visual Policy Editor Per-session policy Configure the Per Session policy as appropriate for your chosen deployment type. Per-request: The per-session policy must contain at least one logon page to set the username variable in the user’s session. Preferably it should also perform some type of primary authentication. This validated username is used later in the per-request policy. Per-session: The per-session policy is used for all authentication. A per-request policy is not used. Figures 14a and 14b show a per-session policy that runs when a client initiates a session. Depending on the actions you include in the access policy, it can authenticate the user and perform actions that populate session variables with data for use throughout the session. Figure 14a: Per-session policy in Visual Policy Editor performs both primary authentication and Duo authentication (for per-session use case) Figure 14b: Per-session policy in Visual Policy Editor performs primary authentication only (for per-request use case) Apply policy/policies and iRule to the APM virtual server Finally, apply the per-request policy, per-session policy, and iRule to the APM virtual server. You assign iRules as a resource to the virtual server that users connect. Configure the virtual server’s default pool to the protected local web resource. Apply policy/policies to the virtual server Per-request policy To attach policies to the virtual server: 1. On the Main tab, click Local Traffic > Virtual Servers. 2. Select the Virtual Server. 3. In the Access Policy section, select the policy you created. 4. Click Finished. Figure 15: Access Policy section in Virtual Server (per-request policy) Per-session policy Figure 16 shows the Access Policy section in Virtual Server when the per-session policy is deployed. Figure 16: Access Policy section in Virtual Server (per-session policy) Apply iRule to the virtual server To attach the iRule to the virtual server: 1. On the Main tab, click Local Traffic > Virtual Servers. 2. Select the Virtual Server. 3. Select the Resources tab. 4. Click Manage in the iRules section. 5. Select an iRule from the Available list and add it to the Enabled list. 6. Click Finished.
Hardeep_Kaur Mar 14, 2024 Place Technical Articles
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OWASP Tactical Access Defense Series: Broken Authentication and BIG-IP APM
The threat of broken authentication poses a significant risk to organizations, potentially leading to unauthorized access and data breaches. In the face of this formidable challenge, F5's Access Policy Manager (APM) emerges as a robust and indispensable solution. By seamlessly integrating advanced authentication mechanisms and comprehensive access controls, F5 BIG-IP APM stands as a stalwart guardian against the vulnerabilities associated with broken authentication. This article explores the pivotal role played by BIG-IP APM in fortifying authentication protocols, mitigating risks, and ensuring a resilient defense against unauthorized access, ultimately safeguarding the integrity and security of sensitive data in today's dynamic digital environment. Broken Authentication Broken Authentication Examples BIG-IP APM and Broken Authentication Related Content Broken Authentication Authentication mechanism is an exposed target due to the nature of this function, as authentication is the first point of entry to any platform. The difficulty to exploit authentication weaknesses differs based on how the authentication platform is secured. In the current digital era the security perimeters are very fluid, and so are the trust boundries for our authentication platforms those require more cautions from the developers and security architects regarding authentication flows. Not only we need to protect authentication endpoints and flows, but also some overlooked items like forget and reset password endpoints. How can we consider endpoint to be vulnerable? Credential stuffing. Brute force attacks targetting users' accounts. Weak Passwords. Sensitive details in the URL (passwords, Tokens). Allow users sensitive actions without confirmation. No validation for the tokens authenticity. Accept unsigned or weak jwt tokens. No validation for jwt expiration. Use of plain-text, non-encrypted or non-hashed passwords. Use of weak encryption algorithms. Endpoint can access each other without proper authentication. Use weak or predictable tokens for intra-endpoint authentication. Broken Authentication Examples Making use of GraphQL query patching to bypass API ratelimiting and brute force user's login. POST /graphql [ {"query":"mutation{login(username:\"victim\",password:\"password\"){token}}"}, {"query":"mutation{login(username:\"victim\",password:\"123456\"){token}}"}, {"query":"mutation{login(username:\"victim\",password:\"qwerty\"){token}}"}, ... {"query":"mutation{login(username:\"victim\",password:\"123\"){token}}"}, ] Update / modify user's sensitive information without API authorization token. PUT /account Authorization: Bearer <token> { "newpassword": "<new_password>" } BIG-IP APM and Broken Authentication We start with creating our Per-Request policy, this policy works in a different way than the per-session policy, as the flow will be evaluted on a per-request basis, making sure to consider variations throught the session life-time. Below are some of the key benefits: Wide range of Authentication, SSO, and MFA mechanisms to properly identify the initiating machine or user. Ability to integrate with 3rd parties to provide additional enforcement decisions based on the organization's policy. Ability to apply endpoint checks on the client side before session initiation. This goes to BIG-IP in general, the ability to apply custom traffic control on both of the traffic sides, Client and Server. The ability to create whitelist / blacklist for API Access tokens, JSON Web Tokens ID (JTI) or a different element based on the used authentication method, below example steps for JWT: Extract JTI value from Access token. Add JTI value to whether Allow/Block lists. Related Content F5 BIG-IP Access Policy Manager | F5 Introduction to OWASP API Security Top 10 2023 OWASP Top 10 API Security Risks – 2023 - OWASP API Security Top 10 API Protection Concepts OWASP Tactical Access Defense Series: How BIG-IP APM Strengthens Defenses Against OWASP Top 10 OWASP Tactical Access Defense Series: Broken Object Level Authorization and BIG-IP APM F5 Hybrid Security Architectures (Part 5 - F5 XC, BIG-IP APM, CIS, and NGINX Ingress Controller)
momahdy Mar 14, 2024 Place Technical Articles
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Crafting Secure Paths: The Intricacies of VPN Solutions on BIG-IP APM
Introduction In this article we are exploring Virtual Private Networks (VPN) solutions on F5 BIG-IP Access Policy Manager (APM), In today's digital landscape, secure connectivity is paramount, and BIG-IP APM stands at the forefront, offering a diverse array of VPN options to suit various needs. In this article, we'll delve into the world of BIG-IP APM VPNs, from their different flavors to the tight integration with other modules that enrich the overall solution. Join us as we unravel the complexities, uncover the nuances, and discover how F5 Networks empowers organizations to craft robust, tailored VPN solutions for their unique requirements. BIG-IP APM VPN Solutions VPN is a mean to connect trusted sites over untrusted medium, a user to a corporate portal, branch to main office or between different data centeres. What makes VPN solutions unique with BIG-IP APM is not just the VPN element but the whole ecosystem within your hands, with multiple Multi-Factor Authenticaiton (MFA) and Single Sign-On (SSO) supported protocols. In addition to tight integration with different modules in BIG-IP. All this gives you as Solution Architect the flexibility to come up with different solutions that suits organizations security posture and expand well in the future for any new requirements. IPSEC VPN You can configure an IPsec tunnel to secure traffic that traverses a wide area network (WAN), from a BIG-IP system to third-party device. You start by configuring an IKE peer to negotiate Phase 1 Internet Security Association and Key Management Protocol (ISAKMP) security associations for the secure channel between two systems. You can also configure a custom traffic selector and a custom IPsec policy that use this secure channel to generate IPsec Tunnel mode (Phase 2) security associations (SAs). While IPSEC is configured via BIG-IP LTM, I've added this one here to cover the different VPN solutions, interesting set of articles already published covering different use cases and troubleshooting items for IPSEC VPN via BIG-IP. BIG-IP to Azure Dynamic IPsec Tunneling Securing ExpressRoute with the BIG-IP and IPsec Simple BIG-IP to BIG-IP, On-prem to Public Cloud IPsec Configuration Guide Understanding IPSec IKEv1 negotiation on Wireshark Understanding IPSec IKEv2 negotiation on Wireshark Passthrough IPSec with AFM SSL VPN Because an SSL VPN uses standard web browsers and technologies, it gives users secure remote access to enterprise applications without requiring the installation and maintenance of separate client software on each user’s computer. Most SSL VPNs also integrate with multiple authentication mechanisms. With the growth of the remote workforce, SSL VPNs are critical to keeping employees connected to the work applications they need—and for IT to ensure that only authorized users gain access. SSL VPNs provide a secure way for your workforce, contractors, and partners worldwide to gain access to sensitive information from virtually any computer or device. Furthermore, they give IT full, granular control over data access. SSL VPNs are becoming more common in the workplace, and the learning curve to implement and use them is minimal. Below are some of the use cases and education resources for VPN deployments via BIG-IP APM. Deploying a VPN on the BIG-IP APM Creating a SSL VPN Using F5 Full Webtop F5 VPN Client from Raspberry Pi SSL VPN Split Tunneling and Office 365 Scaling SSL VPN using BIG-IP Local Traffic Manager (LTM) Rate Limiting SSL VPN User Traffic VPN Split Tunneling: The Benefits and Risks SSL VPN Split Tunneling and Office 365 Remote Desktop Protocol (RDP) using an SSL VPN VPN Access with MFA using Edge Client 7.2.1 and APM 16.0 Connect to the F5 VPN with BIG-IP Edge Client How to optimize SSL VPN connections when BIG-IP is reaching 100% CPU Per-App VPN The Per-Application (Per-App) VPN feature makes sure that specific mobile applications and their data remain secure and protected, and only data relevant from the application is sent to the internal network. With the Per-App VPN capabilities of the BIG-IP APM, combined with a mobile device management (MDM) solution, enterprise organizations can be sure only authenticated and authorized mobile users are able to access and send data to the organization from approved mobile applications or mobile containers. Per-App VPN deploys using an existing MDM solution. Depending on the authentication in use, Per-App VPN can offer a seamless or relatively simple way to access internal resources. You can apply per-user bandwidth policies and ACLs to make sure that users comply with network use policies. Detailed user activity auditing is also possible with ACL logging or solutions based on iRules. You must create the following BIG-IP components for this implementation: A connectivity profile An application tunnel profile (Java and per-App VPN) An MDM-enrolled mobile device An MDM-deployed application BIG-IP Edge Client 2.0.1+ for L3 and Per-App VPN Application tunnel An application tunnel provides secure, application-level TCP/IP connections from the client to the internal network. Application tunnels use iSession, an F5 proprietary protocol for transport. Application tunnels can be started using native Windows binary components or with a browser-based Java applet on Windows, Mac, and Linux platforms. Per-user session-level bandwidth policy and ACLs can be applied to application tunnels. You must create the following BIG-IP components for this implementation: A connectivity profile A full webtop An application tunnel resource An access policy that assigns a webtop and an application tunnel resource Related content Configuring a Per-App VPN Using F5 App Tunnels Deploying a VPN on the BIG-IP APM Creating a SSL VPN Using F5 Full Webtop F5 VPN Client from Raspberry Pi SSL VPN Split Tunneling and Office 365 Scaling SSL VPN using BIG-IP Local Traffic Manager (LTM) How to optimize SSL VPN connections when BIG-IP is reaching 100% CPU BIG-IP to Azure Dynamic IPsec Tunneling Understanding IPSec IKEv1 negotiation on Wireshark Understanding IPSec IKEv2 negotiation on Wireshark Passthrough IPSec with AFM K08200035: Use cases | BIG-IP APM operations guide Configuring IPsec in Tunnel Mode between a Remote Device and BIG-IP using Dynamic Template
momahdy Feb 27, 2024 Place Technical Articles
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APM Cookbook: Single Sign On (SSO) using Kerberos
To get the APM Cookbook series moving along, I’ve decided to help out by documenting the common APM solutions I help customers and partners with on a regular basis. Kerberos SSO is nothing new, but seems to stump people who have never used Kerberos before. Getting Kerberos SSO to work with APM is straight forward once you have the Active Directory components configured. Overview I have a pre-configured web service (IIS 7.5/Sharepoint 2010) that is configured for Windows Authentication, which will send a “Negotiate” in the header of the “401 Request for Authorization”. Make sure the web service is configured to send the correct header before starting the APM configuration by accessing the website directly and viewing the headers using browser tools. In my example, I used the Sharepoint 2010/2013 iApp to build the LTM configuration. I’m using a single pool member, sp1.f5.demo (10.10.30.2) listening on HTTP and the Virtual Server listening on HTTPS performing SSL offload. Step 1 - Create a delegation account on your domain 1.1 Open Active Directory Users and Computers administrative tool and create a new user account. User logon name: host/apm-kcd.f5.demo User logon name (pre-Windows 2000): apm-kcd Set the password and not expire 1.2 Alter the account and set the servicePrincipcalName. Run setspn from the command line: setspn –A host/apm-kcd.f5.demo apm-kcd A delegation tab will now be available for this user. Step 2 - Configure the SPN 2.1 Open Active Directory Users and Computers administrative tool and select the user account created in the previous step. Edit the Properties for this user Select the Delegation tab Select: Trust this user for delegation to specified services only Select: Use any authentication protocol Select Add, to add services. Select Users or Computers… Enter the host name, in my example I will be adding HTTP service for sp1.f5.demo (SP1). Select Check Names and OK Select the http Service Type and OK 2.2 Make sure there are no duplicate SPNs and run setspn –x from the command line. Step 3 - Check Forward and Reverse DNS DNS is critical and a missing PTR is common error I find when troubleshooting Kerberos SSO problems. From the BIG-IP command line test forward and reverse records exist for the web service using dig: # dig sp1.f5.demo ;; QUESTION SECTION: ;sp1.f5.demo. IN A ;; ANSWER SECTION: sp1.f5.demo. 1200 IN A 10.10.30.2 # dig -x 10.10.30.2 ;; QUESTION SECTION: ;2.30.10.10.in-addr.arpa. IN PTR ;; ANSWER SECTION: 2.30.10.10.in-addr.arpa. 1200 IN PTR sp1.f5.demo. Step 4 - Create the APM Configuration In this example I will use a Logon Page to capture the user credentials that will be authenticated against Active Directory and mapped to the SSO variables for the Kerberos SSO. 4.1 Configure AAA Server for Authentication Access Policy >> AAA Servers >> Active Directory >> “Create” Supply the following: Name: f5.demo_ad_aaa Domain Name: f5.demo Domain Controller: (Optional – BIG-IP will use DNS to discover if left blank) Admin Name and Password Select “Finished" to save. 4.2 Configure Kerberos SSO Access Policy >> SSO Configurations >> Kerberos >> “Create” Supply the following: Name: f5.demo_kerberos_sso Username Source: session.sso.token.last.username User Realm Source: session.ad.last.actualdomain Kerberos Realm: F5.DEMO Account Name: apm-kcd (from Step 1) Account Password & Confirm Account Password (from Step1) Select “Finished” to save. 4.3 Create an Access Profile and Policy We can now bring it all together using the Visual Policy Editor (VPE). Access Policy >> Access Profiles >> Access Profile List >> “Create” Supply the following: Name: intranet.f5.demo_sso_ap SSO Configuration: f5.demo_kerberos_sso Languages: English (en) Use the default settings for all other settings. Select “Finished” to save. 4.4 Edit the Access Policy in the VPE Access Policy >> Access Profiles >> Access Profile List >> “Edit” (intranet.f5.demo_sso_ap) On the fallback branch after the Start object, add a Logon Page object. Leave the defaults and “Save”. On the fallback branch after the Logon Page object, add an AD Auth object. Select the Server Select “Save” when your done. On the Successful branch after the AD Auth object, add a SSO Credential Mapping object. Leave the defaults and “Save”. On the fallback branch after the SSO Credential Mapping, change Deny ending to Allow. The finished policy should look similar to this: Don't forget to “Apply Access Policy”. Step 5 – Attach the APM Policy to the Virtual Server and Test 5.1 Edit the Virtual Server Local Traffic >> Virtual Servers >> Virtual Server List >> intranet.f5.demo_vs Scroll down to the Access Policy section and select the Access Profile. Select “Update” to save. 5.2 Test Open a browser, access the Virtual Server URL (https://intranet.f5.demo in my example), authenticate and verify the client is automatically logged on (SSO) to the web service. To verify Kerberos SSO has worked correctly, check /var/log/apm on APM by turning on debug. You should see log events similar to the ones below when the BIG-IP has fetched a Kerberos Ticket. info websso.1[9041]: 014d0011:6: 33186a8c: Websso Kerberos authentication for user 'test.user' using config '/Common/f5.demo_kerberos_sso' debug websso.1[9041]: 014d0018:7: sid:33186a8c ctx:0x917e4a0 server address = ::ffff:10.10.30.2 debug websso.1[9041]: 014d0021:7: sid:33186a8c ctx:0x917e4a0 SPN = HTTP/sp1.f5.demo@F5.DEMO debug websso.1[9041]: 014d0023:7: S4U ======> ctx: 33186a8c, sid: 0x917e4a0, user: test.user@F5.DEMO, SPN: HTTP/sp1.f5.demo@F5.DEMO debug websso.1[9041]: 014d0001:7: Getting UCC:test.user@F5.DEMO@F5.DEMO, lifetime:36000 debug websso.1[9041]: 014d0001:7: fetched new TGT, total active TGTs:1 debug websso.1[9041]: 014d0001:7: TGT: client=apm-kcd@F5.DEMO server=krbtgt/F5.DEMO@F5.DEMO expiration=Tue Apr 29 08:33:42 2014 flags=40600000 debug websso.1[9041]: 014d0001:7: TGT expires:1398724422 CC count:0 debug websso.1[9041]: 014d0001:7: Initialized UCC:test.user@F5.DEMO@F5.DEMO, lifetime:36000 kcc:0x92601e8 debug websso.1[9041]: 014d0001:7: UCCmap.size = 1, UCClist.size = 1 debug websso.1[9041]: 014d0001:7: S4U ======> - NO cached S4U2Proxy ticket for user: test.user@F5.DEMO server: HTTP/sp1.f5.demo@F5.DEMO - trying to fetch debug websso.1[9041]: 014d0001:7: S4U ======> - NO cached S4U2Self ticket for user: test.user@F5.DEMO - trying to fetch debug websso.1[9041]: 014d0001:7: S4U ======> - fetched S4U2Self ticket for user: test.user@F5.DEMO debug websso.1[9041]: 014d0001:7: S4U ======> trying to fetch S4U2Proxy ticket for user: test.user@F5.DEMO server: HTTP/sp1.f5.demo@F5.DEMO debug websso.1[9041]: 014d0001:7: S4U ======> fetched S4U2Proxy ticket for user: test.user@F5.DEMO server: HTTP/sp1.f5.demo@F5.DEMO debug websso.1[9041]: 014d0001:7: S4U ======> OK! Conclusion Like I said in the beginning, once you know how Kerberos SSO works with APM, it’s a piece of cake!
Smithy Feb 25, 2024 Place Technical Articles
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APM Advanced Customization Examples with Modern Template, v15.1+
Introduction This guide will walk through how the logon, webtop, and other UI pages are created by APM, how it works, and some examples.The new APM modern template has an updated look in both mobile and desktop browsers. It uses the popular Preact framework to provide a consistent and familiar end user experience. How to activate the new customization system New policies created in 15.1 and later default to the new Modern template. Existing policies made before 15.1 continue to use the Standard template. When creating a new access policy: You can see the customization types applied to all access policies in the Per-Session access policy menu: Customization Sections Basic, General, and Advanced Customization APM has different ways to customize, depending on the desired complexity. Some administrators simply want to change colors, while others would prefer to completely rewrite the APM user-facing HTML and CSS so they have similar branding to other corporate web properties. As is typical with CSS, style customizations can be applied simultaneously with later style changes overriding earlier ones. Basic Customization Simple customization settings such as images, titles, captions, and colors are applied to resources and policies using Basic Customization. The tables and screenshot below detail the settings. Elements in Basic Customization Header/Footer/Title Header Image for Desktop (Max height: 60px) Header Image for Mobile (Max height: 30px) Layout Settings Maximum viewport width for applying small (mobile) screen styles (px) Browser width for mobile clients Minimum viewport width for applying large (desktop) screen styles (px) Browser width for desktop clients Colors (see image for sections) Active Links and Buttons Color Footer Background Color Form Background Color Header Color Page Background Color Solid Button Text Color Text Color Top Strip Color General Customization General Customization offers a more advanced tree view of the Basic Customization settings as well as text options for user-facing messages. Like Basic customization, the settings are applied individually to each access policy and policy item via the item’s XML file specified in the cache-pathparameter of the associated customization group configuration object. To use General Customization Create the policies and/or resources you would like to customize. Find them in the tree view. Make the changes. Perform the standard 3-step save process: Save Draft, Save, then Apply the access policy. You use General Customization to apply changes to the informational text strings and error messages that are displayed to users. Browse the configuration tree to see the available customization areas. The settings are divided into Branding and Text. Text are the localized messages that are displayed to the end users, including associated HTML. User-facing status and text messages can be selected in the Text tab.Branding options are about page styling, colors, fonts, and the like. These are selected in the Branding tab. Special General Options APM customization has a few non-branding and non-text special options in the configuration tree. Disable all external scripts and styles The new Modern customization includes a new resource loader feature. This feature loads all added CSS and JS resources dynamically, including 3 rd party external code. You use this option like a “Revert” to restore the default branding in case there is some unknown trouble. If enabled, it disables loading of all external CSS and JS, including the APM-hosted user-XXXX.js and user-XXXX.css files. External Javascript / CSS You can now easily add external javascript references, for libraries such as JQuery that you wouldlike your users to load from an external CDN. Historically this would present a security problem because the CDN content may be vulnerable to malicious injection. APM uses the W3C subresource integrity feature(https://www.w3.org/TR/SRI/) mechanism to ensure that the external files are not tampered. You can also specify external scripts manually in user-XXXX.js, but using the inbuilt APM script-loader mechanism allows us to trap loading errors and disable all external scripts globally, in case of any problems (see the previous section). To use this feature: Find the checksum* and URL of your resource. jQuery makes this very simple: It’s directly on their CDN page. Alternatively, you can compute them using srihash.org. Place the values into External Scripts / Styles. Save, Apply the access policy, and visit the access policy virtual. *Note*: APM’s end-user pages are built using Preactwith built-in libraries, so don't load another copy of Preact using this mechanism. See the Advanced Examples section below for usage ideas. If the checksum is incorrect the stock APM javascript will function correctly, but the external resource will not be loaded and the browser will produce a “Failed to find a valid digest in the integrity attribute for resource ‘xxxxxx’” error in the console similar to this screenshot: * Supported checksum mechanisms are SHA-256, SHA-384, or SHA-512. Advanced Customization Use Advanced Customization to edit or place code directly into the files that are referenced from the primary APM user-facing HTML. Common settings are available which load on all pages, along with separate CSS and JS for each policy item that is present in the policy. Generally, the CSS/JS for each policy item load after the common settings so later settings will override earlier ones. You must first add policy items to customize before customizing them. This is a customization tree view before and after adding Logon Page to access policy: Before After Operation of Advanced Customization With Advanced Customization, you can do essentially any styling you want using standard CSS. Advanced Customization has some common settings, agent settings, and some special settings. After making any change, Save Draft, then Save., then Apply the access policy. Common settings These two files (user-common.css and user-common.js) are loaded on all* APM user-facing pages, including policy evaluation (logon, message, etc), webtop, and logout. Use these if you want to change a page style in all areas. For example, perhaps we always want to hide the header and footer and add a background image. To do that, we can simply add some CSS to user-common.css to set a few properties targeting the apmui-header, apmui-main, and apmui-footer CSS selectors. Example: logon page customization Hide header and footer, and add a picture: *Note*: You should usually make logon-specific changes on the logon page rather than “common”, since the webtop places some GUI links in apmui-header. Hiding the header removes access to these links! You can useuser-common.jsto load a tracker such as Google Analytics. Example: Google Analytics Customization Types There are two broad categories for the customization of APM objects: Resources areAssigned during per-session access policy execution. They include customizable icons, captions, and descriptions that are visible on the APM full webtop (sometimes called a portal). OAuth Client App OAuth Scope App Tunnel Network Access Remote Desktop SAML Web App (Portal Access) Webtop Link Webtop Section Non-Resourceseach have different configuration properties General Framework Installation EPS Logout (Ending Denied) Error message Decision Box Confirm/Continue Ending Denied Message Box Oauth Authz Webtop Screenshots *Example*: Simple resource customization of a webtop link resource End-User view from APM webtop: Troubleshooting Tips: Configuration Structure Resource customization settings, text strings, and image files are stored as interdependent configuration and file objects. When troubleshooting, check the following configuration areas. This diagram represents the dependencies: This table represents the item details, and troubleshooting tips: NOTE: To create resource customization using scripting or automation, they must be created all at once using a TMSH transaction rather than individually because of the interdependency between resources, profiles, policies, policy items, agents, and customization groups. To get started, use the GUI to create a policy you like, then review the configuration objects defined in tmsh list apm.The objects inter-referred-to must be copied into a transaction. equivalent create apm xxxx commands inside of a transaction. For detail on transactions with APM policies, see tmsh help apm policy access-policy tmsh help cli transaction HTML Rendering Details Access profiles, Per Request Policies and other objects (customized independently from an access profile) share similar syntaxand structure. Each object has customization settings. Access Profiles have multiple groups of customization settings. Every time you change customization, it generates a set of files that are combined to form the user-displayed page. Settings (color, font, text, and so on) for the header and footer can be defined in access profile customization. Settings for the location and alignment of the content area can also be defined in access profile customization. Settings forresourcesdisplayed in the APM Webtop can be defined in the resource's configuration area (see payroll example above). APM Sandbox / Image Hosting To place images or other files in APM for convenient access by end users, use the Hosted Content feature. On a BIG-IP system, on the Main tab, clickAccess > Webtops > Hosted Content > Manage Files. Upload an image file. Click Upload >> Manage Access, and make sure the checkbox for your access policy attached to the virtual server is selected. Access the file at the location indicated in thePublicly Accessible URIcolumn. General Examples Execute external javascript code after Logon Page browser rendering is complete. This example can be placed into user-logon.js to use the D3 library to display a small pop-up message. Additional code can be inserted for custom functions. define(["require", "exports", "tslib", "module", "apmui/page/logon/View"], function (require, exports, tslib_1, module, View_1) { "use strict"; Object.defineProperty(exports, "__esModule", { value: true }); requirejs.config({ map: { 'apmui/master/View': { 'apmui/page/logon/View': module.id, }, }, }); /* Replacement View component */ var CustomLogonView = /** @class */ (function (_super) { tslib_1.__extends(CustomLogonView, _super); function CustomLogonView() { return _super !== null && _super.apply(this, arguments) || this; } CustomLogonView.prototype.componentDidMount = function () { _super.prototype.componentDidMount.call(this); requirejs(['https://d3js.org/d3.v6.min.js'], function (d3) { // Place your code inside this function d3.select("form").append("span") .text("Hello from D3 library"); }); }; return CustomLogonView; }(View_1.default)); exports.default = CustomLogonView; }); Execute local javascript code inside Logon Page. This example can be placed into user-logon.js to perform custom actions. define(["require", "exports", "tslib", "module", "apmui/page/logon/View"], function (require, exports, tslib_1, module, View_1) { "use strict"; Object.defineProperty(exports, "__esModule", { value: true }); requirejs.config({ map: { 'apmui/master/View': { 'apmui/page/logon/View': module.id, }, }, }); /* Replacement View component */ var CustomLogonView = /** @class */ (function (_super) { tslib_1.__extends(CustomLogonView, _super); function CustomLogonView() { return _super !== null && _super.apply(this, arguments) || this; } CustomLogonView.prototype.componentDidMount = function () { _super.prototype.componentDidMount.call(this); alert('PLACE CUSTOM CODE HERE'); }; return CustomLogonView; }(View_1.default)); exports.default = CustomLogonView; }); Advanced Examples These use TypeScript and preact You should be familiar with these technologies and their usage. To use these examples, you need a standard TypeScript/NodeJS+NPM build environment. This can be most easily achieved by using Linux, Microsoft Windows Subsystem for Linux (WSL), or Mac, then installing NodeJS which includes NPM. The examples are attached to this article as a ZIP archive. Download and decompress this file to a suitable location on your workstation. Read README.md from the package. Each example here assumes you have already downloaded the package and run npm install; npm run build. The compilation result is placed in the dist directory. For each one of the examples, you simply copy the user-xxxx.css and user-xxxx.js files into the correct object in Advanced Customization. To make changes to these examples, modify the files in src, then npm run build, as specified in README.md. Example 1: Decision box with more options By default, the APM Decision Box has only two choices. We can use this advanced customization example to append additional choices. Follow this procedure: Add a decision box to your access policy. Navigate to customization-examples/dist/decisionBox-more-options and copy the contents of user-decision.js to the appropriate area in Advanced Customization. Click Save Draft, Save, and apply the access policy. As a user, navigate to the decision box on the APM virtual server. Now the decision box has 4 options rather than two. The option and icon detail are in the example user-decision.ts source file: The result: value is the raw POST data, which is transferred from the client browser when the my.policy page is submitted. It must match an agent expression in the branch rules defined for the decision box object. As with all other agents, the branch rules must be defined in the policy-item configuration so that the additional branches are available in the VPE for use: Once these additional branch rules are defined, they can be added to the VPE flow: When a user makes a choice, it appears in log files thusly: To host your own icons, you can use the APM sandbox hosting feature, discussed elsewhere in this doc. Example 2: Logon box custom component This example adds a custom Preactcomponent to the Logon Box. Add a Logon Page to your access policy, then copy the example dist code into your user-logon.js and user-logon.css files. Output: Example 3: Logon custom view This is an example of how to obtain a JSON-formatted dump of data available programmatically. Add the code from logon-custom-view to your APM policy files, then visit the APM virtual. You will see JSON data that provides the detailed data available. Example 4: PIN Pad replaces standard forms logon page This is an example of an alternative method of rendering a standard forms logon page with a polymorphic virtual PIN pad. It uses Preactand CSS to achieve this result. Note: A similar result with a virtual keyboard is possible as well, using other modules available via npm. This requires Preactdevelopment. As with the other examples, compile the TypeScript and place the dist’s user-logon.css and user-logon.js into the APM’s advanced customization area for your logon agent. The result when visiting this logon page is illustrated in this screenshot: Example 5: Validation of input fields logon-validate-domain contains a sample that has an example of input field validation: The input validation logic can be changed with the following TypeScript: This kind of validation logic can be extended for almost any purpose. Example 6: Pin resource to top of webtop Recently-used-resources implements a mechanism that uses local storage to track how many times a resource has been clicked. It also creates a new webtop section that displays most-clicked-on resources. You must have a full webtop and multiple resources assigned to the user (any type is fine). Use this example like the others: Copy the dist directory files user-webtop.css and user-webtop.js to the advanced customization object and click Save Draft, then Save, and apply the access policy. Note that you may have to clear BIG-IP or browser cache to see the update. Take a few minutes to examine the browser's Local Storage contents while clicking various favorites assigned to the user. Example 7: Pin resources on full webtop Most application portals offer some kind of system to save often-used resources at the top of the list. This example uses HTML5 Browser Local Storage to save the user’s resources and render them at the top of the webtop application portal. You must assign a full webtop and multiple resources to the user. Use this example like the others: Copy the dist directory files user-webtop.css and user-webtop.js to the advanced customization object and click Save Draft, then Save, and apply the access policy. Note that you may have to clear BIG-IP or browser cache to see the update. Afterwards, logon as a user to the webtop and click the corner pin icon to add the resource to Pinned Resources. Try to log out and back in and see that the resource(s) are saved. Check the browser developer tools to query the local storage contents. Examples Conclusion We hope these examples are helpful to performing customization of APM web pages. Please let us know of any further examples that you would like to share! Request For Examples We have received the following requests for examples and hope to add these soon. Let us know if you can contribute! Simplest way to add an HTML link and text into the logon page Simplest way to add a select box to a logon page Example virtual keyboard logon page Attributions / Licensing / Support Status Support Status: F5 Support cannot provide assistance with TypeScript, JavaScript, or Preactcoding or web development. To validate the operation of any of these examples, standard web development practices should be used. F5 code: These examples include code produced by F5 intended to showcase the possibilities of the v15.1.0 APM customization system and can be used by any APM customer. THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 3 rd Party Code: As with most open source software, each module in this example includes a separate license (MIT, CC, etc). Before using any of these in a production environment, please review the licensing requirements for each NPM package in node_modules. Media: Beach scene used in customization examples:Stones in the Beach By Xavierfsc - Own work, CC BY 4.0, https://commons.wikimedia.org/w/index.php?curid=84430607
Lucas_Thompson Feb 19, 2024 Place Technical Articles
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A Brief Introduction To External Application Verification Monitors
Background EAVs (External Application Verification) monitors are one of most useful and extensible features of the BIG-IP product line. They give the end user the ability to utilize the underlying Linux operating system to perform complex and thorough service checks. Given a service that does not have a monitor provided, a lot of users will assign the closest related monitor and consider the solution complete. There are more than a few cases where a TCP or UDP monitor will mark a service “up” even while the service is unresponsive. EAVs give us the ability to dive much deeper than merely performing a 3-way handshake and neglecting the other layers of the application or service. How EAVs Work An EAV monitor is an executable script located on the BIG-IP’s file system (usually under /usr/bin/monitors) that is executed at regular intervals by the bigd daemon and reports its status. One of the most common misconceptions (especially amongst those with *nix backgrounds) is that the exit status of the script dictates the fate of the pool member. The exit status has nothing to do with how bigd interprets the pool member’s health. Any output to stdout (standard output) from the script will mark the pool member “up”. This is a nuance that should receive special attention when architecting your next EAV. Analyze each line of your script and make sure nothing will inadvertently get directed to stdout during monitor execution. The most common example is when someone writes a script that echoes “up” when the checks execute correctly and “down” when they fail. The pool member will be enabled by the BIG-IP under both circumstances rendering a useless monitor. Bigd automatically provides two arguments to the EAV’s script upon execution: node IP address and node port number. The node IP address is provided with an IPv6 prefix that may need to be removed in order for the script to function correctly. You’ll notice we remove the “::ffff://” prefix with a sed substitution in the example below. Other arguments can be provided to the script when configured in the UI (or command line). The user-provided arguments will have offsets of $3, $4, etc. Without further ado, let’s take a look at a service-specific monitor that gives us a more complete view of the application’s health. An Example I have seen on more than one occasion where a DNS pool member has successfully passed the TCP monitor, but the DNS service was unresponsive. As a result, a more invasive inspection is required to make sure that the DNS service is in fact serving valid responses. Let’s take a look at an example: #!/bin/bash # $1 = node IP # $2 = node port # $3 = hostname to resolve [[ $# != 3 ]] && logger -p local0.error -t ${0##*/} -- "usage: ${0##*/} <node IP> <node port> <hostname to resolve>" && exit 1 node_ip=$(echo $1 | sed 's/::ffff://') dig +short @$node_ip $3 IN A &> /dev/null [[ $? == 0 ]] && echo “UP” We are using the dig (Domain Information Groper) command to query our DNS server for an A record. We use the exit status from dig to determine if the monitor will pass. Notice how the script will never output anything to stdout other than “UP” in the case of success. If there aren’t enough arguments for the script to proceed, we output the usage to /var/log/ltm and exit. This is a very simple 13 line script, but effective example. The Takeaways The command should be as lightweight and efficient as possible If the same result can be accomplished with a built-in monitor, use it EAV monitors don’t rely on the command’s exit status, only standard output Send all error and informational messages to logger instead of stdout or stderr (standard error) “UP” has no significance, it is just a series of character sent to stdout, the monitor would still pass if the script echoed “DOWN” Conclusion When I first discovered EAV monitors, it opened up a whole realm of possibilities that I could not accomplish with built in monitors. It gives you the ability to do more thorough checking as well as place logic in your monitors. While my example was a simple bash script, BIG-IP also ships with Perl and Python along with their standard libraries, which offer endless possibilities. In addition to using the built-in commands and libraries, it would be just as easy to write a monitor in a compiled language (C, C++, or whatever your flavor may be) and statically compile it before uploading it to the BIG-IP. If you are new to EAVs, I hope this gives you the tools to make your environments more robust and resilient. If you’re more of a seasoned veteran, we’ll have more fun examples in the near future.
George_Watkins_Dec 14, 2023 Place Technical Articles
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F5 Predicts: Education gets personal
The topic of education is taking centre stage today like never before. I think we can all agree that education has come a long way from the days where students and teachers were confined to a classroom with a chalkboard. Technology now underpins virtually every sector and education is no exception. The Internet is now the principal enabling mechanism by which students assemble, spread ideas and sow economic opportunities. Education data has become a hot topic in a quest to transform the manner in which students learn. According to Steven Ross, a professor at the Centre for Research and Reform in Education at Johns Hopkins University, the use of data to customise education for students will be the key driver for learning in the future[1].This technological revolution has resulted in a surge of online learning courses accessible to anyone with a smart device. A two-year assessment of the massive open online courses (MOOCs) created by HarvardX and MITxrevealed that there were 1.7 million course entries in the 68 MOOC [2].This translates to about 1 million unique participants, who on average engage with 1.7 courses each. This equity of education is undoubtedly providing vast opportunities for students around the globe and improving their access to education. With more than half a million apps to choose from on different platforms such as the iOS and Android, both teachers and students can obtain digital resources on any subject. As education progresses in the digital era, here are some considerations for educational institutions to consider: Scale and security The emergence of a smogasborad of MOOC providers, such as Coursera and edX, have challenged the traditional, geographical and technological boundaries of education today. Digital learning will continue to grow driving the demand for seamless and user friendly learning environments. In addition, technological advancements in education offers new opportunities for government and enterprises. It will be most effective if provided these organisations have the ability to rapidly scale and adapt to an all new digital world – having information services easily available, accessible and secured. Many educational institutions have just as many users as those in large multinational corporations and are faced with the issue of scale when delivering applications. The aim now is no longer about how to get fast connection for students, but how quickly content can be provisioned and served and how seamless the user experience can be. No longer can traditional methods provide our customers with the horizontal scaling needed. They require an intelligent and flexible framework to deploy and manage applications and resources. Hence, having an application-centric infrastructure in place to accelerate the roll-out of curriculum to its user base, is critical in addition to securing user access and traffic in the overall environment. Ensuring connectivity We live in a Gen-Y world that demands a high level of convenience and speed from practically everyone and anything. This demand for convenience has brought about reform and revolutionised the way education is delivered to students. Furthermore, the Internet of things (IoT), has introduced a whole new raft of ways in which teachers can educate their students. Whether teaching and learning is via connected devices such as a Smart Board or iPad, seamless access to data and content have never been more pertinent than now. With the increasing reliance on Internet bandwidth, textbooks are no longer the primary means of educating, given that students are becoming more web oriented. The shift helps educational institutes to better personalise the curriculum based on data garnered from students and their work. Duty of care As the cloud continues to test and transform the realms of education around the world, educational institutions are opting for a centralised services model, where they can easily select the services they want delivered to students to enhance their learning experience. Hence, educational institutions have a duty of care around the type of content accessed and how it is obtained by students. They can enforce acceptable use policies by only delivering content that is useful to the curriculum, with strong user identification and access policies in place. By securing the app, malware and viruses can be mitigated from the institute’s environment. From an outbound perspective, educators can be assured that students are only getting the content they are meant to get access to. F5 has the answer BIG-IP LTM acts as the bedrock for educational organisations to provision, optimise and deliver its services. It provides the ability to publish applications out to the Internet in a quickly and timely manner within a controlled and secured environment. F5 crucially provides both the performance and the horizontal scaling required to meet the highest levels of throughput. At the same time, BIG-IP APM provides schools with the ability to leverage virtual desktop infrastructure (VDI) applications downstream, scale up and down and not have to install costly VDI gateways on site, whilst centralising the security decisions that come with it. As part of this, custom iApps can be developed to rapidly and consistently deliver, as well as reconfigure the applications that are published out to the Internet in a secure, seamless and manageable way. BIG-IP Application Security Manager (ASM) provides an application layer security to protect vital educational assets, as well as the applications and content being continuously published. ASM allows educational institutes to tailor security profiles that fit like a glove to wrap seamlessly around every application. It also gives a level of assurance that all applications are delivered in a secure manner. Education tomorrow It is hard not to feel the profound impact that technology has on education. Technology in the digital era has created a new level of personalised learning. The time is ripe for the digitisation of education, but the integrity of the process demands the presence of technology being at the forefront, so as to ensure the security, scalability and delivery of content and data. The equity of education that technology offers, helps with addressing factors such as access to education, language, affordability, distance, and equality. Furthermore, it eliminates geographical boundaries by enabling the mass delivery of quality education with the right policies in place. [1] http://www.wsj.com/articles/SB10001424052702304756104579451241225610478 [2] http://papers.ssrn.com/sol3/papers.cfm?abstract_id=2586847
Jezmynn_Koh_429 Nov 04, 2023 Place Technical Articles
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Configuring a Per-App VPN Using F5 App Tunnels
So if anyone of you has sat in a tech talk of mine, I am sure you have heard me mention the use of F5 app tunnels or split tunnel VPN's. The capability is very similar to the article I wrote about in regards to network access on DevCentral which can be found here though in this case, we are using a split tunnel capability to allow VPN access to a single application. When might this be useful? Well the use cases I have seen are for logical Out of Band management solutions and in the event, a user requires network access to internal resources though they do not have permissions to install a VPN client on their workstation. Prerequisites LTM licensed and provisioned APM licensed and provisioned Create a Connectivity Profile Navigate to Access >> Connectivity / VPN >> Profiles. Click Add. Profile Name*: demo_connectivity_profile Parent Profile*: /Common/connectivity Click OK. Create a Webtop Navigate to Access >> Webtops >> Webtop Lists. Click Create. Name: demo_webtop Type: Full Click Finished. Create an App Tunnel Object When you create an app tunnel object, that object becomes a simple container that holds app tunnel resources. Once you specify those resources from within the app tunnel resource, you can then assign the resource to an access policy. Navigate to Access >> Connectivity / VPN >> App Tunnels . Click Create. Name: demo_app_tunnel Caption: demo_app_tunnel Click Create. Configure an App Tunnel Resource Navigate to Access >> Connectivity / VPN > >App Tunnels . Click demo_app_tunnel. Under Resource Items, click Add. Destination: 10.1.20.134 Port(s): 443 Application Path: C:\Program Files (x86)\Google\Chrome\Application\chrome.exe Note: This is the application on the client side that will be launched when the app tunnel is selected from the webtop. I am using Chrome as an example though real-world use cases can also include other apps such as putty to access resources in an organizations DMZ over port 22. Parameters: https://%host%/xui Note: If using Host Name, ensure the hostname or fqdn is resolvable by the client that will be connecting to this resource. If you use DNS and it does not show up on the webtop, it is due to the client being unable to resolve that resource. Click Finished. Create a Per-Session Access Policy Navigate to Access > > Profiles / Policies >> Profiles / Policies : Access Profiles (Per-Session Policies). Click Create. Name: demo_ap Profile Type: All Profile Scope: Profile Languages: The language of your choice Click Finished. When redirected back to the Access Profiles page, select Edit in the same row as the access policy created in the previous step. Between Start and Deny click +. From the Assignment tab, select Advanced Resource Assign. Click Add Item. Click Add new entry. Click Add/Delete. From the App Tunnel tab, select the app tunnel created in previous steps. From the Webtop tab, select demo_webtop. Click Update. Click Save. Select Deny from the Visual Policy Editor (VPE). Change the ending to Allow. Click Save. Click Apply Access Policy. Create a Virtual Server and Assign Resources Navigate to Local Traffic >> Virtual Servers. Click Create. Name: demo_app_tunnel Type: Standard Destination Address/Mask: 10.1.10.123 Service Port: 443 Protocol Profile (Client): f5-tcp-wan HTTP Profile: http SSL Profile (Client): clientssl SSL Profile (Server): serverssl Source Address Translation: Auto Map Access Profile: demo_ap Connectivity Profile: demo_connectivity_profile Click Finished. Validating App Tunnel Functionality Navigate to a browser of your choice and attempt to access the IP or hostname of the virtual server created in the previous step. From the webtop, click demo_app_tunnel. If prompted with a Security Alert regarding a Network Access/Application Tunnel attempt, click either the Add or Allow option. If prompted regarding launching an application, click Yes. In this example, Chrome is launched and navigated to the portal access resource created in the steps above. You can also launch the F5 VPN icon in the system tray which will show the results of your tunnel. In this how-to guide, we successfully created a per-app VPN to the BIG-IP Traffic Management User Interface as a quick example. So I didn't lose everyone, I did not include authentication or endpoint checks as it would have certainly increased the size of this guide significantly. However, to give you an idea of what a complete solution may look like, take a look at the VPE below. Until next time!
Steve_Lyons Oct 04, 2023 Place Technical Articles
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DevCentral Top 5: Sep 8, 2014
But soft! What light through yonder window breaks? It is the east, and this week's edition of the DevCentral Top 5 is the sun. Yep, you guessed it. The top 5 is back...but unlike Shakespeare's Romeo and Juliet, this is no tragedy. Rather, it's a celebration of the most awesome articles you'll read anywhere on the Internet. Our DevCentral authors have been writing with freakish speed and determination, and they have turned out quality articles that are simply second to none. Choosing only five articles was a tough task given all the great content out there, but here's my take on the top articles since our last posting. F5 SOC Malware Summary Report: Neverquest I literally could have chosen five Lori MacVittie articles for this "top 5" but I resisted the urge and only chose one. In this article, Lori explains the details of a Trojan known as "Neverquest" that has been active since July 2013. Most of us get that warm, fuzzy, secure feeling when using 2-factor authentication because, you know, it's got 2 factors! Maybe automated malware has a shot at cracking one factor, but two? No way. Well, apparently Neverquest has found a way to automate the demise of our beloved 2FA. Lori does a magnificent job of explaining how Neverquest works, and then she discusses the amazing work that was completed by our F5 Security Operations Center in their analysis of this malware (in case you didn't know, F5 has a Security Operations Center that analyzes malware like this and provides amazing reports that are free for anyone to read). Lori provides links to the downloads of the executive summary as well as the full technical analysis of Neverquest. This one is not optional...if you care about anything at all, you gotta read this one. Leveraging BIG-IP APM for seamless client NTLM Authentication Michael Koyfman reminds us why we love the BIG-IP APM...transparent seamless authentication for users. In this article, Michael specifically discusses how to configure the APM to perform client NTLM authentication and use it in the context of sending a SAML assertion to the Office 365 service. This is a step-by-step masterpiece that shows you exactly what to do at every turn. In the end, you point your browser to the FQDN of the APM virtual server and you will be silently authenticated (let's be honest...silent authentication is a bucket-list item for each and every one of us). Michael also reminds us of the SSO options at the end of his article. Webshells Nir Zigler introduces us to Webshells (web scripts that act as a control panel for the server running them), and talks about some of the common uses for these scripts. But you know the story...scripts that were created for good can also be used for evil. After Nir explains all the valid uses for legitimate webshells, he takes us to a place where mere mortals dare not tread...through a webshell attack. He gives us an overview of how a webshell attack works, and then he explains some of the specific tools that are used for these nefarious actions. After walking through the power and functionality of an open source webshell called b374k, Nir shows how this tool can be used to attack an unsuspecting user. But have no fear! Nir finishes up the article by discussing the power of the BIG-IP ASM and how it will detect and prevent webshell attacks. Continuing the DDoS Arms Race How long have DDoS attacks been around, and why are they still news today? Because they are consistently one of the top attack vectors that companies face today. Shauntine'z discusses the DDoS arms race and provides some poignant statistics that remind us of the very real and credible DDoS threat. But the article doesn't stop there...it goes on to provide some excellent tips on what to do to strengthen your DDoS defense posture (it even has a well-placed picture of Professor John Frink...you gotta check this one out). Last, Shauntine'z reveals new features that are loaded in the latest release of the BIG-IP...version 11.6. The AFM and ASM have some new and exciting capabilities that are "must haves" for any company that is serious about securing their applications and critical business functions. (Editors note: the LineRate product has been discontinued for several years. 09/2023) Why ECC and PFS Matter: SSL offloading with LineRate We all know that sensitive data traverses our networks every day. We also know it's critically important to secure this information. We also know that SSL/TLS is the primary method used to secure said information. Andrew Ragone discusses SSL offloading and tells us why Elliptical Curve Cryptography (ECC) and Perfect Forward Secrecy (PFS) are great candidates for securing your information. He highlights the advantages of the software based LineRate solution, and gives great examples of why LineRate is the clear-cut winner over any existing software-based or hardware-based SSL/TLS offload solutions. Andrew also published another series of articles related to this very topic, and in these articles he walks you through the exact steps needed to configure SSL certificates and offload SSL on LineRate. On that subject...if you haven't had a chance to check out LineRate and learn all about the awesomeness that it is, do yourself a favor and visit
ltwagnon Sep 26, 2023 Place Technical Articles
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APM-DHCP Access Policy Example and Detailed Instructions
Prepared with Mark Quevedo, F5 Principal Software Engineer May, 2020 Sectional Navigation links Important Version Notes || Installation Guide || What Is Going On Here? || Parameters You Set In Your APM Access Policy || Results of DHCP Request You Use in Access Policy || Compatibility Tips and Troubleshooting Introduction Ordinarily you assign an IP address to the “inside end” of an APM Network Tunnel (full VPN connection) from an address Lease Pool, from a static list, or from an LDAP or RADIUS attribute. However, you may wish to assign an IP address you get from a DHCP server. Perhaps the DHCP server manages all available client addresses. Perhaps it handles dynamic DNS for named client workstations. Or perhaps the DHCP server assigns certain users specific IP addresses (for security filtering). Your DHCP server may even assign client DNS settings as well as IP addresses. APM lacks DHCP address assignment support (though f5's old Firepass VPN had it ). We will use f5 iRules to enable DHCP with APM. We will send data from APM session variables to the DHCP server so it can issue the “right” IP address to each VPN tunnel based on user identity, client info, etc. Important Version Notes Version v4c includes important improvements and bug fixes. If you are using an older version, you should upgrade. Just import the template with “Overwrite existing templates” checked, then “reconfigure” your APM-DHCP Application Service—you can simply click “Finished” without changing any options to update the iRules in place. Installation Guide First install the APM-DHCP iApp template (file DHCP_for_APM.tmpl). Create a new Application Service as shown (choose any name you wish). Use the iApp to manage the APM-DHCP virtual servers you need. (The iApp will also install necessary iRules.) You must define at least one APM-DHCP virtual server to receive and send DHCP packets. Usually an APM-DHCP virtual server needs an IP address on the subnet on which you expect your DHCP server(s) to assign client addresses. You may define additional APM-DHCP virtual servers to request IP addresses on additional subnets from DHCP. However, if your DHCP server(s) support subnet-selection (see session.dhcp.subnet below) then you may only need a single APM-DHCP virtual server and it may use any IP that can talk to your DHCP server(s). It is best to give each APM-DHCP virtual server a unique IP address but you may use an BIG-IP Self IP as per SOL13896 . Ensure your APM and APM-DHCP virtual servers are in the same TMOS Traffic Group (if that is impossible set TMOS db key tmm.sessiondb.match_ha_unit to false). Ensure that your APM-DHCP virtual server(s) and DHCP server(s) or relay(s) are reachable via the same BIG-IP route domain. Specify in your IP addresses any non-zero route-domains you are using (e.g., “192.168.0.20%3”)—this is essential. (It is not mandatory to put your DHCP-related Access Policy Items into a Macro—but doing so makes the below screenshot less wide!) Into your APM Access Policy, following your Logon Page and AD Auth (or XYZ Auth) Items (etc.) but before any (Full/Advanced/simple) Resource Assign Item which assigns the Network Access Resource (VPN), insert both Machine Info and Windows Info Items. (The Windows Info Item will not bother non-Windows clients.) Next insert a Variable Assign Item and name it “DHCP Setup”. In your “DHCP Setup” Item, set any DHCP parameters (explained below) that you need as custom session variables. You must set session.dhcp.servers. You must also set session.dhcp.virtIP to the IP address of an APM-DHCP virtual server (either here or at some point before the “DHCP_Req” iRule Event Item). Finally, insert an iRule Event Item (name it “DHCP Req”) and set its Agent ID to DHCP_req. Give it a Branch Rule “Got IP” using the expression “expr {[mcget {session.dhcp.address}] ne ""}” as illustrated. You must attach iRule ir-apm-policy-dhcp to your APM virtual server (the virtual server to which your clients connect). Neither the Machine Info Item nor the Windows Info Item is mandatory. However, each gathers data which common DHCP servers want to see. By default DHCP_req will send that data, when available, to your DHCP servers. See below for advanced options: DHCP protocol settings, data sent to DHCP server(s), etc. Typically your requests will include a user identifier from session.dhcp.subscriber_ID and client (machine or connection) identifiers from other parameters. The client IP address assigned by DHCP will appear in session.dhcp.address. By default, the DHCP_req iRule Event handler will also copy that IP address into session.requested.clientip where the Network Access Resource will find it. You may override that behavior by setting session.dhcp.copy2var (see below). Any “vendor-specific information” supplied by the DHCP server 1 (keyed by the value of session.dhcp.vendor_class) will appear in variables session.dhcp.vinfo.N where N is a tag number (1-254). You may assign meanings to tag numbers. Any DNS parameters the DHCP server supplies 2 are in session.dhcp.dns_servers and session.dhcp.dns_suffix. If you want clients to use those DNS server(s) and/or DNS default search domain, put the name of every Network Access Resource your Access Policy may assign to the client into the session.dhcp.dns_na_list option. NB: this solution does not renew DHCP address leases automatically, but it does release IP addresses obtained from DHCP after APM access sessions terminate. 3 Please configure your DHCP server(s) for an address lease time longer than your APM Maximum Session Timeout. Do not configure APM-DHCP virtual servers in different BIG-IP route domains so they share any part of a DHCP client IP range (address lease pool). For example, do not use two different APM-DHCP virtual servers 10.1.5.2%6 and 10.1.5.2%8 with one DHCP client IP range 10.1.5.10—10.1.5.250. APM-DHCP won’t recognize when two VPN sessions in different route domains get the same client IP from a non-route-domain-aware DHCP server, so it may not release their IP’s in proper sequence. This solution releases DHCP address leases for terminated APM sessions every once in a while, when a new connection comes in to the APM virtual server (because the BIG IP only executes the relevant iRules on the “event” of each new connection). When traffic is sparse (say, in the middle of the night) there may be some delay in releasing addresses for dead sessions. If ever you think this solution isn’t working properly, be sure to check the BIG IP’s LTM log for warning and error messages. DHCP Setup (a Variable Assign Item) will look like: Put the IP of (one of) your APM-DHCP virtual server(s) in session.dhcp.virtIP. Your DHCP server list may contain addresses of DHCP servers or relays. You may list a directed broadcast address (e.g., “172.16.11.255”) instead of server addresses but that will generate extra network chatter. To log information about DHCP processing for the current APM session you may set variable session.dhcp.debug to true (don’t leave it enabled when not debugging). DHCP Req (an iRule Event Item) will look like: Note DHCP Req branch rules: If DHCP fails, you may wish to warn the user: (It is not mandatory to Deny access after DHCP failure—you may substitute another address into session.requested.clientip or let the Network Access Resource use a Lease Pool.) What is going on here? We may send out DHCP request packets easily enough using iRules’ SIDEBAND functions, but it is difficult to collect DHCP replies using SIDEBAND. 4 Instead, we must set up a distinct LTM virtual server to receive DHCP replies on UDP port 67 at a fixed address. We tell the DHCP server(s) we are a DHCP relay device so replies will come back to us directly (no broadcasting). 5 For a nice explanation of the DHCP request process see http://technet.microsoft.com/en-us/library/cc940466.aspx. At this time, we support only IPv4, though adding IPv6 would require only toil, not genius. By default, a DHCP server will assign a client IP on the subnet where the DHCP relay device (that is, your APM-DHCP virtual server) is homed. For example, if your APM-DHCP virtual server’s address were 172.30.4.2/22 the DHCP server would typically lease out a client IP on subnet 172.30.4.0. Moreover, the DHCP server will communicate directly with the relay-device IP so appropriate routes must exist and firewall rules must permit. If you expect to assign client IP’s to APM tunnel endpoints on multiple subnets you may need multiple APM-DHCP virtual servers (one per subnet). Alternatively, some but not all DHCP servers 6 support the rfc3011 “subnet selection” or rfc3527 “subnet/link-selection sub-option” so you can request a client IP on a specified subnet using a single APM-DHCP virtual server (relay device) IP which is not homed on the target subnet but which can communicate easily with the DHCP server(s): see parameter session.dhcp.subnet below. NOTE: The subnet(s) on which APM Network Access (VPN) tunnels are homed need not exist on any actual VLAN so long as routes to any such subnet(s) lead to your APM (BIG-IP) device. Suppose you wish to support 1000 simultaneous VPN connections and most of your corporate subnets are /24’s—but you don’t want to set up four subnets for VPN users. You could define a virtual subnet—say, 172.30.4.0/22—tell your DHCP server(s) to assign addresses from 172.30.4.3 thru 172.30.7.254 to clients, put an APM-DHCP virtual server on 172.30.4.2, and so long as your Layer-3 network knows that your APM BIG-IP is the gateway to 172.30.4.0/22, you’re golden. When an APM Access Policy wants an IP address from DHCP, it will first set some parameters into APM session variables (especially the IP address(es) of one or more DHCP server(s)) using a Variable Assign Item, then use an iRule Event Item to invoke iRule Agent DHCP_req in ir apm policy dhcp. DHCP_req will send DHCPDISCOVERY packets to the specified DHCP server(s). The DHCP server(s) will reply to those packets via the APM-DHCP virtual-server, to which iRule ir apm dhcp must be attached. That iRule will finish the 4-packet DHCP handshake to lease an IP address. DHCP_req handles timeouts/retransmissions and copies the client IP address assigned by the DHCP server into APM session variables for the Access Policy to use. We use the APM Session-ID as the DHCP transaction-ID XID and also (by default) in the value of chaddr to avert collisions and facilitate log tracing. Parameters You Set In Your APM Access Policy Required Parameters session.dhcp.virtIP IP address of an APM-DHCP virtual-server (on UDP port 67) with iRule ir-apm-dhcp. This IP must be reachable from your DHCP server(s). A DHCP server will usually assign a client IP on the same subnet as this IP, though you may be able to override that by setting session.dhcp.subnet. You may create APM-DHCP virtual servers on different subnets, then set session.dhcp.virtIP in your Access Policy (or branch) to any one of them as a way to request a client IP on a particular subnet. No default. Examples (“Custom Expression” format): expr {"172.16.10.245"} or expr {"192.0.2.7%15"} session.dhcp.servers A TCL list of one or more IP addresses for DHCP servers (or DHCP relays, such as a nearby IP router). When requesting a client IP address, DHCP packets will be sent to every server on this list. NB: IP broadcast addresses like 10.0.7.255 may be specified but it is better to list specific servers (or relays). Default: none. Examples (“Custom Expression” format): expr {[list "10.0.5.20" "10.0.7.20"]} or expr {[list "172.30.1.20%5"]} Optional Parameters (including some DHCP Options) NOTE: when you leave a parameter undefined or empty, a suitable value from the APM session environment may be substituted (see details below). The defaults produce good results in most cases. Unless otherwise noted, set parameters as Text values. To exclude a parameter entirely set its Text value to '' [two ASCII single-quotes] (equivalent to Custom Expression return {''} ). White-space and single-quotes are trimmed from the ends of parameter values, so '' indicates a nil value. It is best to put “Machine Info” and “Windows Info” Items into your Access Policy ahead of your iRule Event “DHCP_req” Item (Windows Info is not available for Mac clients beginning at version 15.1.5 as they are no longer considered safe). session.dhcp.debug Set to 1 or “true” to log DHCP-processing details for the current APM session. Default: false. session.dhcp.firepass Leave this undefined or empty (or set to “false”) to use APM defaults (better in nearly all cases). Set to “true” to activate “Firepass mode” which alters the default values of several other options to make DHCP messages from this Access Policy resemble messages from the old F5 Firepass product. session.dhcp.copy2var Leave this undefined or empty (the default) and the client IP address from DHCP will be copied into the Access Policy session variable session.requested.clientip, thereby setting the Network Access (VPN) tunnel’s inside IP address. To override the default, name another session variable here or set this to (Text) '' to avert copying the IP address to any variable. session.dhcp.dns_na_list To set the client's DNS server(s) and/or DNS default search domain from DHCP, put here a Custom Expression TCL list of the name(s) of the Network Access Resource(s) you may assign to the client session. Default: none. Example: expr {[list "/Common/NA" "/Common/alt-NA"]} session.dhcp.broadcast Set to “true” to set the DHCP broadcast flag (you almost certainly should not use this). session.dhcp.vendor_class Option 60 A short string (32 characters max) identifying your VPN server. Default: “f5 APM”. Based on this value the DHCP server may send data to session.dhcp.vinfo.N (see below). session.dhcp.user_class Option 77 A Custom Expression TCL list of strings by which the DHCP server may recognize the class of the client device (e.g., “kiosk”). Default: none (do not put '' here). Example: expr {[list "mobile" "tablet"]} session.dhcp.client_ID Option 61 A unique identifier for the remote client device. Microsoft Windows DHCP servers expect a representation of the MAC address of the client's primary NIC. If left undefined or empty the primary MAC address discovered by the Access Policy Machine Info Item (if any) will be used. If no value is set and no Machine Info is available then no client_ID will be sent and the DHCP server will distinguish clients by APM-assigned ephemeral addresses (in session.dhcp.hwcode). If you supply a client_ID value you may specify a special code, a MAC address, a binary string, or a text string. Set the special code “NONE” (or '') to avoid sending any client_ID, whether Machine Info is available or not. Set the special code “XIDMAC” to send a unique MAC address for each APM VPN session—that will satisfy DHCP servers desiring client_ID‘s while averting IP collisions due to conflicting Machine Info MAC’s like Apple Mac Pro’s sometimes provide. A value containing twelve hexadecimal digits, possibly separated by hyphens or colons into six groups of two or by periods into three groups of four, will be encoded as a MAC address. Values consisting only of hexadecimal digits, of any length other than twelve hexits, will be encoded as a binary string. A value which contains chars other than [0-9A-Fa-f] and doesn't seem to be a MAC address will be encoded as a text string. You may enclose a text string in ASCII single-quotes (') to avert interpretation as hex/binary (the quotes are not part of the text value). On the wire, MAC-addresses and text-strings will be prefixed by type codes 0x01 and 0x00 respectively; if you specify a binary string (in hex format) you must include any needed codes. Default: client MAC from Machine Info, otherwise none. Example (Text value): “08-00-2b-2e-d8-5e”. session.dhcp.hostname Option 12 A hostname for the client. If left undefined or empty, the short computer name discovered by the APM Access Policy Windows Info Item (if any) will be used. session.dhcp.subscriber_ID Sub-option 6 of Option 82 An identifier for the VPN user. If undefined or empty, the value of APM session variable session.logon.last.username will be used (generally the user's UID or SAMAccountName). session.dhcp.circuit_ID Sub-option 1 of Option 82 An identifier for the “circuit” or network endpoint to which client connected. If left undefined or empty, the IP address of the (current) APM virtual server will be used. session.dhcp.remote_ID Sub-option 2 of Option 82 An identifier for the client's end of the connection. If left undefined or empty, the client’s IP address + port will be used. session.dhcp.subnet Option 118 Sub-option 5 of Option 82 The address (e.g., 172.16.99.0) of the IP subnet on which you desire a client address. With this option you may home session.dhcp.virtIP on another (more convenient) subnet. MS Windows Server 2016 added support for this but some other DHCP servers still lack support. Default: none. session.dhcp.hwcode Controls content of BOOTP htype, hlen, and chaddr fields. If left undefined or empty, a per-session value optimal in most situations will be used (asserting that chaddr, a copy of XID, identifies a “serial line”). If your DHCP server will not accept the default, you may set this to “MAC” and chaddr will be a locally-administered Ethernet MAC (embedding XID). When neither of those work you may force any value you wish by concatenating hexadecimal digits setting the value of htype (2 hexits) and chaddr (a string of 0–32 hexits). E.g., a 6-octet Ethernet address resembles “01400c2925ea88”. Most useful in the last case is the MAC address of session.dhcp.virtIP (i.e., a specific BIG-IP MAC) since broken DHCP servers may send Layer 2 packets directly to that address. Results of DHCP Request For Use In Access Policy session.dhcp.address <-- client IP address assigned by DHCP! session.dhcp.message session.dhcp.server, session.dhcp.relay session.dhcp.expires, session.dhcp.issued session.dhcp.lease, session.dhcp.rebind, session.dhcp.renew session.dhcp.vinfo.N session.dhcp.dns_servers, session.dhcp.dns_suffix session.dhcp.xid, session.dhcp.hex_client_id, session.dhcp.hwx If a DHCP request succeeds the client IP address appears in session.dhcp.address. If that is empty look in session.dhcp.message for an error message. The IP address of the DHCP server which issued (or refused) the client IP is in session.dhcp.server (if session.dhcp.relay differs then DHCP messages were relayed). Lease expiration time is in session.dhcp.expires. Variables session.dhcp.{lease, rebind, renew} indicate the duration of the address lease, plus the rebind and renew times, in seconds relative to the clock value in session.dhcp.issued (issued time). See session.dhcp.vinfo.N where N is tag number for Option 43 vendor-specific information. If the DHCP server sends client DNS server(s) and/or default search domain, those appear in session.dhcp.dns_servers and/or session.dhcp.dns_suffix. To assist in log analysis and debugging, session.dhcp.xid contains the XID code used in the DHCP request. The client_ID value (if any) sent to the DHCP server(s) is in session.dhcp.hex_client_id. The DHCP request’s htype and chaddr values (in hex) are concatenated in session.dhcp.hwx. Compatibility Tips and Troubleshooting Concern Response My custom parameter seems to be ignored. You should set most custom parameters as Text values (they may morph to Custom Expressions). My users with Apple Mac Pro’s sometimes get no DHCP IP or a conflicting one. A few Apple laptops sometimes give the Machine Info Item bogus MAC addresses. Set session.dhcp.client_ID to “XIDMAC“ to use unique per-session identifiers for clients. After a VPN session ends, I expect the very next session to reuse the same DHCP IP but that doesn’t happen. Many DHCP servers cycle through all the client IP’s available for one subnet before reusing any. Also, after a session ends APM-DHCP takes a few minutes to release its DHCP IP. When I test APM-DHCP with APM VE running on VMware Workstation, none of my sessions gets an IP from DHCP. VMware Workstation’s built-in DHCP server sends bogus DHCP packets. Use another DHCP server for testing (Linux dhcpd(8) is cheap and reliable). I use BIG-IP route domains and I notice that some of my VPN clients are getting duplicate DHCP IP addresses. Decorate the IP addresses of your APM-DHCP virtual servers, both in the iApp and in session.dhcp.virtIP, with their route-domain ID’s in “percent notation” like “192.0.2.5%3”. APM-DHCP is not working. Double-check your configuration. Look for errors in the LTM log. Set session.dhcp.debug to “true” before trying to start a VPN session, then examine DHCP debugging messages in the LTM log to see if you can figure out the problem. Even after looking at debugging messages in the log I still don’t know why APM-DHCP is not working. Run “tcpdump –ne -i 0.0 -s0 port 67” to see where the DHCP handshake fails. Are DISCOVER packets sent? Do any DHCP servers reply with OFFER packets? Is a REQUEST sent to accept an OFFER? Does the DHCP server ACK that REQUEST? If you see an OFFER but no REQUEST, check for bogus multicast MAC addresses in the OFFER packet. If no OFFER follows DISCOVER, what does the DHCP server’s log show? Is there a valid zone/lease-pool for you? Check the network path for routing errors, hostile firewall rules, or DHCP relay issues. Endnotes In DHCP Option 43 (rfc2132). In DHCP Options 6 and 15 (rfc2132). Prior to version v3h, under certain circumstances with some DHCP servers, address-release delays could cause two active sessions to get the same IP address. And even more difficult using [listen], for those of you in the back of the room. A bug in some versions of VMware Workstation’s DHCP server makes this solution appear to fail. The broken DHCP server sends messages to DHCP relays in unicast IP packets encapsulated in broadcast MAC frames. Anormal BIG-IP virtual server will not receive such packets. As of Winter 2017 the ISC, Cisco, and MS Windows Server 2016 DHCP servers support the subnet/link selection options but older Windows Server and Infoblox DHCP servers do not. Supporting Files - Download attached ZIP File Here.
Chase_Abbott Sep 08, 2023 Place Technical Articles
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