F5 BIG-IP iRule based TCL DNS server
Short Description This code is for the purpose if there is a need to return a custom DNS reply not from the main DNS server but from the F5 Virtual Server. Problem solved by this Code Snippet The code is meant for small lab or dev environments as F5 has F5 DNS/GTM for replying to DNS requests with Intelligent Load Balancing, DNS Express Memory cache etc. How to use this Code Snippet Modify the irule code to configure the custom domain you want replies from the irule code and not the real DNS server. Add the irule to a DNS UDP LB Code Snippet Meta Information Version: 17.1 Coding Language: TCL Code You can find the code and further documentation in my GitHub repository: irule_dns/irule1 at main · Nikoolayy1/irule_dns (github.com)
Json parsing with iRules
JSON is now the format of choice for most APIs. It's time we were able to parse JSON with F5 iRules too, as simple string matching is not always good enough. That's why I wrote a simple JSON parser for iRules. It is a validating single pass parser that processes the JSON string char by char until the JsonPath expression matches, no recursion or any other fancy stuff. As I do not wanted to reinvent the wheel, it is basically a rewrite of the JSON parser found in themongoose webserver project in plain TCL. The usage is very simple: set token [call json::json_get_tok { $json $path }] $json is the json string to parse $path is a JsonPath expression, following operators are implemented: Operator Description $ The root element to query. This starts all path expressions. .<name> Dot-notated child. [<number>] Array index. Example Simple JSON: { "aud": "audience \"test\"", "iss": "https://issuer.de/issuer/", "iat": 1701422123, "roles": [ "role1", "role2" ], "obj": { "sub": "adcad2b8", }, "ver": "2.0" } JsonPath expression to parse this simple JSON: JsonPath Return value $.aud "audience \"test\"" $.iat 1701422123 $.obj.sub "adcad2b8" $.roles[0] "role1" To decode the extracted JSON string: set decoded [call json::json_decode_str { $token }] This removes the enclosing quotes from a string and decodes JSON escapes. Code You can find the code and further documentation in my GitHub repository: https://github.com/JuergenMang/f5-irules-json
iRule to decode WebSocket negotiation and frames
Problem this snippet solves: WebSocket establishes a socket via HTTP upgrade and once socket is established subsequent messages are non-HTTP, but WebSocket frame. There might be a situation where you want to dump WebSocket negotiation and frame into log for troubleshooting purpose. This iRule dumps negotiation and WebSocket frame header fields, and payload (only text data). WebSocket frame format looks as below. RFC 6455 - 5.2. Base Framing Protocol 0 1 2 3 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 +-+-+-+-+-------+-+-------------+-------------------------------+ |F|R|R|R| opcode|M| Payload len | Extended payload length | |I|S|S|S| (4) |A| (7) | (16/64) | |N|V|V|V| |S| | (if payload len==126/127) | | |1|2|3| |K| | | +-+-+-+-+-------+-+-------------+ - - - - - - - - - - - - - - - + | Extended payload length continued, if payload len == 127 | + - - - - - - - - - - - - - - - +-------------------------------+ | |Masking-key, if MASK set to 1 | +-------------------------------+-------------------------------+ | Masking-key (continued) | Payload Data | +-------------------------------- - - - - - - - - - - - - - - - + : Payload Data continued ... : + - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - + | Payload Data continued ... | +---------------------------------------------------------------+ WebSocket frame is quite simple. The first 2 bytes are necessary and always present. Extended payload length exists only when Payload length is set to 126 (in this case Ext len is 16 bits) or 127 (in this case Ext len is 64 bits). Masking-key exists only if MASK bit is set to 1. FIN : If the frame is the last frame, set to 1. If payload is fragmented, the last frame should have FIN = 1. Other fragmented ones should have FIN = 0. RSV : If extension is not used, it is set to 0 opcode : This tells you if it is data frame (can be text or binary) or control frame. %x0:continuation frame %x1:text frame %x2:binary frame %x3-7:reserved for further %x8:connection close %x9:ping %xA:pong %xB-F:reserved for further MASK : When browser sends a data, this bit MUST be set to 1, which means data is masked using the Masking-key. When server sends a data, this bit MUST NOT set to 1 Payload len : If 0 - 125, this field represents the payload length If it is 126, then the Extended payload length (16bit) are used to tell the actual payload length (maximum data size is 65535 bytes) If it is 127, then the Extended payload length (64bit : MSB must be 0) are used to tell the actual payload length (maximum data size is 9223372036854775807 bytes) Extended payload length Only when Payload len is set to 126 Extended payload length_continued Only when Payload len is set to 127 Masking-key Used to mask data. Masking is to avoid proxy poisoning. Non-compliant HTTP proxy caches WebSocket data. If MASK bit is 1, this field is present. If MASK bit is 0, this field is not present. Client sets this key and it must be unpredictable. Payload Payload from client to server is masked using Masking-key. How to use this snippet: Here I am sending text data "DEAD BEEF" in WebSocket frame via WebSocket_cURL.py (https://github.com/jussmen/WebSocket_cURL). HTTP request and response (negotiation) look like below. $ python WebSocket_cURL.py 10.10.148.101 80 -s "DEAD BEEF" GET /ws HTTP/1.1 Host: 10.10.148.101 Connection: Upgrade Upgrade: websocket Sec-WebSocket-Version: 13 Sec-WebSocket-Key: n5twxG/tNPf8h3po+pNrPA== User-Agent: IE HTTP/1.1 101 Switching Protocols Upgrade: websocket Connection: Upgrade Sec-WebSocket-Accept: y9WDs+d4zDl+qvQ7H17KpnP0EhI= This is how iRule dumps the negotiation and subsequent WebSocket frames in /var/log/ltm <ws_request>: ============================================= <ws_request>: Client 10.10.1.2:47427 -> 10.10.148.101/ws (request) <ws_request>: Host: 10.10.148.101 <ws_request>: Connection: Upgrade <ws_request>: Upgrade: websocket <ws_request>: Sec-WebSocket-Version: 13 <ws_request>: Sec-WebSocket-Key: n5twxG/tNPf8h3po+pNrPA== <ws_request>: User-Agent: IE <ws_request>: ============================================= <ws_response>: ============================================= <ws_response>: Client 10.10.1.2:47427 -> 10.10.148.101/ws (response) <ws_response>: Upgrade: websocket <ws_response>: Connection: Upgrade <ws_response>: Sec-WebSocket-Accept: y9WDs+d4zDl+qvQ7H17KpnP0EhI= <ws_response>: ============================================= <ws_server_frame>: ============================================= <ws_server_frame>: FIN bit : 1 <ws_server_frame>: MASK bit : 1 <ws_server_frame>: MASK : 0 <ws_server_frame>: Type : Text - 1 <ws_server_frame>: ============================================= <ws_server_data>: ============================================= <ws_server_data>: The server says: 'Hello'. Connection was accepted. <ws_server_data>: ============================================= <ws_client_frame>: ============================================= <ws_client_frame>: FIN bit : 1 <ws_client_frame>: MASK bit : 1 <ws_client_frame>: MASK : 1178944834 <ws_client_frame>: Type : Text - 1 <ws_client_frame>: ============================================= <ws_client_data>: ============================================= <ws_client_data>: DEAD BEEF <ws_client_data>: ============================================= <ws_server_frame>: ============================================= <ws_server_frame>: FIN bit : 1 <ws_server_frame>: MASK bit : 1 <ws_server_frame>: MASK : 0 <ws_server_frame>: Type : Text - 1 <ws_server_frame>: ============================================= <ws_server_data>: ============================================= <ws_server_data>: The server says: DEAD BEEF back at you <ws_server_data>: ============================================= <ws_client_frame>: ============================================= <ws_client_frame>: FIN bit : 1 <ws_client_frame>: MASK bit : 1 <ws_client_frame>: MASK : 1178944834 <ws_client_frame>: Type : Connection close - 8 <ws_client_frame>: ============================================= <ws_server_frame>: ============================================= <ws_server_frame>: FIN bit : 1 <ws_server_frame>: MASK bit : 1 <ws_server_frame>: MASK : 0 <ws_server_frame>: Type : Connection close - 8 <ws_server_frame>: ============================================= Code : when WS_REQUEST { # Copied from : https://devcentral.f5.com/s/articles/log-http-headers set LogString "Client [IP::client_addr]:[TCP::client_port] -> [HTTP::host][HTTP::uri]" log local0. "=============================================" log local0. "$LogString (request)" foreach aHeader [HTTP::header names] { log local0. "$aHeader: [HTTP::header value $aHeader]" } log local0. "=============================================" } when WS_RESPONSE { # Copied from : https://devcentral.f5.com/s/articles/log-http-headers log local0. "=============================================" log local0. "$LogString (response)" foreach aHeader [HTTP::header names] { log local0. "$aHeader: [HTTP::header value $aHeader]" } log local0. "=============================================" } when WS_CLIENT_FRAME { log local0. "=============================================" log local0. "FIN bit : [WS::frame eom]" log local0. "MASK bit : [WS::frame orig_masked]" if { [WS::frame orig_masked] eq 0 } { log local0. "Not masked. Client frame MUST be masked." } if { [WS::frame orig_masked] eq 1 } { log local0. "MASK : [WS::frame mask]" } switch -glob [WS::frame type] { "0" { log local0. "Type : Continuatoin frame - 0" } "1" { log local0. "Type : Text - 1" WS::collect frame } "2" { log local0. "Type : Binary - 2" } "3" - "4" - "5" - "6" - "7" { log local0. "Type : Reserved type (3-7) - [WS::frame type]" } "8" { log local0. "Type : Connection close - 8" } "9" { log local0. "Type : ping - 9" } "10" { log local0. "Type : pong - 10" } "11" - "12" - "13" - "14" - "15" { log local0. "Type : Reserved type (11-15) - [WS::frame type]" } } log local0. "=============================================" } when WS_SERVER_FRAME { log local0. "=============================================" log local0. "FIN bit : [WS::frame eom]" log local0. "MASK bit : [WS::frame orig_masked]" if { [WS::frame orig_masked] eq 1 } { log local0. "MASK : [WS::frame mask]" } switch -glob [WS::frame type] { "0" { log local0. "Type : Continuatoin frame - 0" } "1" { log local0. "Type : Text - 1" WS::collect frame } "2" { log local0. "Type : Binary - 2" } "3" - "4" - "5" - "6" - "7" { log local0. "Type : Reserved type (3-7) - [WS::frame type]" } "8" { log local0. "Type : Connection close - 8" } "9" { log local0. "Type : ping - 9" } "10" { log local0. "Type : pong - 10" } "11" - "12" - "13" - "14" - "15" { log local0. "Type : Reserved type (11-15) - [WS::frame type]" } } log local0. "=============================================" } #when WS_CLIENT_FRAME_DONE { #log local0. "WS_CLIENT_FRAME_DONE" #} #when WS_SERVER_FRAME_DONE { #log local0. "WS_SERVER_FRAME_DONE" #} when WS_CLIENT_DATA { log local0. "=============================================" log local0. "[WS::payload]" log local0. "=============================================" WS::release } when WS_SERVER_DATA { log local0. "=============================================" log local0. "[WS::payload]" log local0. "=============================================" WS::release } Tested this on version: 12.0Send an One Time Password (OTP) via the MessageBird SMS gateway
Problem this snippet solves: This snippet makes it possible to send an One Time Password (OTP) via the MessageBird SMS gateway. This snippet uses iRuleLX and the node.js messagebird package to interact with the MessageBird API. How to use this snippet: Prepare the BIG-IP Provision the BIG-IP with iRuleLX. Create LX Workspace: messagebird Add iRule: messagebird_irule Add Extension: messagebird_extension Add LX Plugin: messagebird_plugin -> From Workspace: messagebird Install the node.js messagebird module # cd /var/ilx/workspaces/Common/messagebird/extensions/messagebird_extension # npm install messagebird --save messagebird@2.1.4 node_modules/messagebird # irule To make it works, you need to install the irule on the Virtual Server that publish your application with APM authentication. access profile If you already have an existing access profile, you will need to modify it and include some additionnal configuration in your VPE. If you have no access profile, you can starts building your own based on the description we provide below. Configuring the Visual Policy Editor The printscreen below is a minimal Visual Policy Editor used to make MessageBird OTP Authentication works properly : For a larger version of this image please download here. Irule Event – MessageBird This is an irule event with the ID set to ‘MessageBird’. This will trigger the messagebird_irule to come into action. MessageBird Status This is an empty action with two branches. The branch named "successful" contains the following expression : expr { [mcget {session.custom.messagebird.status}] contains "successful" } Message Box This is a message box that will inform the user that there was a failure sending the One Time Password. messagebird_irule ### ### Name : messagebird_irule ### Author : Niels van Sluis, <niels@van-sluis.nl> ### Version: 20180721.001 ### Date : 2018-07-21 ### when ACCESS_POLICY_AGENT_EVENT { if { [ACCESS::policy agent_id ] eq "MessageBird" } { # Set MessageBird access key set accessKey "<ACCESS_KEY>" # Set user-friendly message which will be send prior to the OTP itself set message "Your OTP is: " # Set username used for logging purposes only set username "[ACCESS::session data get session.logon.last.username]" # Set OTP generated by BIG-IP APM which will be added to the SMS message. set generatedOTP "[ACCESS::session data get session.otp.assigned.val]" # Set phonenumber to send the SMS to set telephoneNumber "[ACCESS::session data get session.ad.last.attr.telephoneNumber]" # Set the sender of the message. This can be a telephone number (including country code) or an alphanumeric string. # In case of an alphanumeric string, the maximum length is 11 characters. set sender "MessageBird" if {[info exists username] && ($username eq "")} { log local0. "Error: username variable is empty; no OTP sent." return } if {[info exists generatedOTP] && ($generatedOTP eq "")} { log local0. "Error: generatedOTP variable is empty; no OTP sent for user $username." return } if {([info exists telephoneNumber] && $telephoneNumber eq "")} { log local0. "Error: telephoneNumber variable is empty; no OTP sent for user $username." return } set rpc_handle [ ILX::init messagebird_plugin messagebird_extension ] if {[ catch { ILX::call $rpc_handle sendOTP $generatedOTP $telephoneNumber $sender $message $accessKey } result ] } { log local0. "sendOTP failed for telephoneNumber: $telephoneNumber, ILX failure: $result" return } log local0. "MessageBird status for user $username ($telephoneNumber): $result" ACCESS::session data set session.custom.messagebird.status $result } } Code : /** *** Name : messagebird_extension *** Author : Niels van Sluis, *** Version: 20180721.001 *** Date : 2018-07-21 **/ // Import the f5-nodejs module. var f5 = require('f5-nodejs'); // Create a new rpc server for listening to TCL iRule calls. var ilx = new f5.ILXServer(); ilx.addMethod('sendOTP', function(req, res) { var generatedOTP = req.params()[0]; var telephoneNumber = req.params()[1]; var sender = req.params()[2]; var message = req.params()[3]; var accessKey = req.params()[4]; var params = { 'originator': sender, 'recipients': [ telephoneNumber ], 'body': message + generatedOTP }; var messagebird = require('messagebird')(accessKey); messagebird.messages.create(params, function (err, response) { if (err) { //console.log(err); return res.reply('failed'); } //console.log(response); return res.reply('successful'); }); }); // Start listening for ILX::call and ILX::notify events. ilx.listen(); Tested this on version: 13.0Pwned Passwords Check
Problem this snippet solves: This snippet makes it possible to use Troy Hunt’s ‘Pwned Passwords’ API. By using this API one can check if the password being used was exposed in earlier data breaches. You can use this information to deny access to highly secure resources or to force a user to first change it’s password to one that isn’t known to be exposed to earlier data breaches. Or you could choose to just to inform a user that it would be wise to change it’s password. It’s good to note that the password itself will not be shared while using this API. This snippet uses a mathematical property called k-anonymity. For more information about k-anonymity and Troy Hunt’s ‘Pwned Passwords’ API see: https://www.troyhunt.com/ive-just-launched-pwned-passwords-version-2/ This snippet also uses Patt-tom McDonnell’s hibp-checker node package. How to use this snippet: Prepare the BIG-IP Provision the BIG-IP with iRuleLX. Create LX Workspace: hibp Add iRule: hibp-irule Add Extension: hibp-extension Add LX Plugin: hibp-plugin -> From Workspace: hibp Install the node.js hibp-checker module # cd /var/ilx/workspaces/Common/hibp/extensions/hibp-extension/ # npm install hibp-checker --save /var/ilx/workspaces/Common/hibp/extensions/hibp-extension └── hibp-checker@1.0.0 # irule To make it works, you need to install the irule on the Virtual Server that publish your application with APM authentication. access profile If you already have an existing access profile, you will need to modify it and include some additionnal configuration in your VPE. If you have no access profile, you can starts building your own based on the description we provide below. Configuring the Visual Policy Editor The printscreen below is an example Visual Policy Editor on how you can use the Pnwed Password snippet. VA – Force Password Change This is a Variable Assignment agent that triggers APM to show a Change Password window. Set variable: session.logon.last.change_password to Custom Expression: expr { 1 } VA – Get Password This is a Variable Assignment agent that copies the password to a session variable that can be read by the hibp irule. Set variable: session.custom.hibp.password to Custom Expression: return [mcget -secure {session.logon.last.password}] IE - HIBP This is an irule event with the ID set to ‘hibp’. This will trigger the hibp_irule to come into action. EA – HIBP Verdict This is an Empty Action with two branches. The branch named "Not Pwned" contains the following expression : expr { [mcget -nocache {session.custom.hibp.status} ] == 0 } MB – Exposed Password This is a message box that will inform the user that it’s password was exposed in earlier data breaches and a password change is needed. The message could be something like this: The password you are using was found in %{session.custom.hibp.status} data breaches. In order to be compliant with our security policy, you must change your password. hibp_irule when ACCESS_POLICY_AGENT_EVENT { if { [ACCESS::policy agent_id ] eq "hibp" } { set password [ACCESS::session data get session.custom.hibp.password] set failonerror 0 if { $password eq "" } { log local0. "Error: no password set" ACCESS::session data set session.custom.hibp.status $failonerror return } set rpc_handle [ ILX::init hibp-plugin hibp-extension ] if {[ catch { ILX::call $rpc_handle -timeout 12000 hibpCheck $password } result ] } { log local0. "hibpCheck failed. ILX failure: $result" ACCESS::session data set session.custom.hibp.status $failonerror return } ACCESS::session data set session.custom.hibp.status [expr { $result }] } } Code : var f5 = require('f5-nodejs'); const checkPassword = require('hibp-checker'); // Create a new rpc server for listening to TCL iRule calls. var ilx = new f5.ILXServer(); ilx.addMethod('hibpCheck', function(req, res) { var password = req.params()[0]; var breachCount = checkPassword(password); breachCount.then(function(result) { return res.reply(result); }, function(err) { return res.reply(err); }); }); // Start listening for ILX::call and ILX::notify events. ilx.listen(); Tested this on version: 13.0PowerShell to iRule AES-CBC conversation using random IV values
Problem this snippet solves: Hi Folks, I saw recently on the DevCentral boards that people are struggeling to securely exchange AES encrypted information between a Windows System and LTM. Although some DevCentral members already managed it by using static IV (Initialization Vectors) on both sites, this approach should be considered as a very bad practise, since it allows an adversary to pulloff certain crypto analyses/attacks which could already lead to a security breach. The snippets below will outline how to implement AES-CBC decryption/encryption with dynamic IV values on Windows using PowerShell and on LTM using iRules. The outlined snippets are alligned to each other by using the same AES crypto settings (Key-Size, Block-Size, CBC-Mode and Padding-Mode) and IV exchange techniques to become interoperable. The implemented IV exchange technique will generate a fresh and random IV on each single encryption and simply prepended the AES-IV to the AES-Ciphertext before passing it to the receiver. The receiver then splits the received AES-Cipherstring into the contained AES-IV and AES-Ciphertext values and finally decrypt the AES-Ciphertext by using the shared AES-Key. From Windows to LTM 1. Import the follwing PS functions on the Windows side function Create-AesKey($KeySize) { $AesManaged = New-Object "System.Security.Cryptography.AesManaged" $AesManaged.KeySize = $KeySize $AesManaged.GenerateKey() [System.Convert]::ToBase64String($AesManaged.Key) } function Encrypt-Data($AesKey, $Data) { $Data = [System.Text.Encoding]::UTF8.GetBytes($Data) $AesManaged = New-Object "System.Security.Cryptography.AesManaged" $AesManaged.Mode = [System.Security.Cryptography.CipherMode]::CBC $AesManaged.Padding = [System.Security.Cryptography.PaddingMode]::PKCS7 $AesManaged.BlockSize = 128 $AesManaged.KeySize = 256 $AesManaged.Key = [System.Convert]::FromBase64String($AesKey) $Encryptor = $AesManaged.CreateEncryptor() $EncryptedData = $Encryptor.TransformFinalBlock($Data, 0, $Data.Length); [byte[]] $EncryptedData = $AesManaged.IV + $EncryptedData $AesManaged.Dispose() [System.Convert]::ToBase64String($EncryptedData) } function Decrypt-Data($AesKey, $Data) { $Data = [System.Convert]::FromBase64String($Data) $AesManaged = New-Object "System.Security.Cryptography.AesManaged" $AesManaged.Mode = [System.Security.Cryptography.CipherMode]::CBC $AesManaged.Padding = [System.Security.Cryptography.PaddingMode]::PKCS7 $AesManaged.BlockSize = 128 $AesManaged.KeySize = 256 $AesManaged.IV = $Data[0..15] $AesManaged.Key = [System.Convert]::FromBase64String($AesKey) $Decryptor = $AesManaged.CreateDecryptor(); $DecryptedData = $Decryptor.TransformFinalBlock($Data, 16, $Data.Length - 16); $aesManaged.Dispose() [System.Text.Encoding]::UTF8.GetString($DecryptedData) } 2. Generate a fresh 256bit AESKey on your Windows System and store it locally as well as on your F5. Create-AesKey 256 iTEEieok7//RyzrPe5mWwz1yroPPsm4e5cqghdEHIlU= 3. Encrypt some data using the AES-Shared-Key $encrypted = Encrypt-Data " iTEEieok7//RyzrPe5mWwz1yroPPsm4e5cqghdEHIlU=" "Hello World!" $encrypted W5xFrWz72U/vt95HG6fHWIuDDHpuhj2HB42E4SIrNwo= Note: Every single encryption should have a different outcome. Thanks to the random IV! 4. Pass the AES-Cipherstring to your LTM and decrypt it using the snippet below set aes_key [b64decode "iTEEieok7//RyzrPe5mWwz1yroPPsm4e5cqghdEHIlU="] set aes_cipherstring [b64decode "W5xFrWz72U/vt95HG6fHWIuDDHpuhj2HB42E4SIrNwo="] binary scan $aes_cipherstring a16a* aes_iv aes_ciphertext set aes_plaintext [CRYPTO::decrypt -alg aes-256-cbc -key $aes_key -iv $aes_iv $aes_ciphertext] log local0.debug "Plaintext = $aes_plaintext" Log Output : Plaintext = Hello World! From LTM to Windows 1. AES encrypt some data on your LTM using the snippet below set aes_key [b64decode "iTEEieok7//RyzrPe5mWwz1yroPPsm4e5cqghdEHIlU="] set aes_plaintext "Hello World!!" set aes_iv [CRYPTO::keygen -alg random -passphrase "MyIVSeed" -len 128] set aes_ciphertext [CRYPTO::encrypt -alg aes-256-cbc -key $aes_key -iv $aes_iv $aes_plaintext] set aes_cipherstring [b64encode [binary format a*a* $aes_iv $aes_ciphertext]] log local0.debug "Cipherstring = $aes_cipherstring" Log Output : Cipherstring = vCIizWalo4KWO+3bLuTUp5iD0J3kArrcZS1fKDue89M= Note: Every single encryption should also have a different outcome. Thanks to the random IV! 2. Pass the AES-Cipherstring to your Windows system and decrypt it using the snippet below $decrypted = Decrypt-Data "iTEEieok7//RyzrPe5mWwz1yroPPsm4e5cqghdEHIlU=" "vCIizWalo4KWO+3bLuTUp5iD0J3kArrcZS1fKDue89M=" $decrypted Hello World!! Cheers, Kai How to use this snippet: See above... Code : See above...
Disable DNS Express to allow recursion of a delegated sub-domain
Problem this snippet solves: If you are using GTM to act both a authoritative slave with DNS Express and as a recursive cache, recursion will not work if a request is made for a delegated sub-domain if the parent domain exists in DNS Express. i.e. domain.com exists in DNS Express but has delegated the dev.domain.com sub-domain to a different set of name server. Any request to dev.domain.com will just get a referral rather than being recursed. This is because of the order of operations in GTM, https://support.f5.com/kb/en-us/solutions/public/14000/500/sol14510.html. Recursion is the very last process that could happen and since DNS Express makes an authoritative referral response no recursion will occur. How to use this snippet: To use this your listener and corresponding DNS profile need to have DNS Express configured and recursion enabled(cache). Then the iRule just needs to be attached to the listener. Code : when DNS_REQUEST { #query DNS Express to look for a sub-domain delegation set rrr [DNS::query dnsx [DNS::question name] [DNS::question type]] #evaluate if the queried zone is defined in DNS Express #empty response indicates DNS Express does not have the requested domain #so we should exit and continue to recursion if {$rrr equals "{} {} {}"}{return} #check if DNS Express response is a delegated sub-domain referral if { [lindex $rrr 0] equals "" && [DNS::type [lindex [lindex $rrr 1] 0]] equals "NS"} { #no ANSWER was returned AND AUTHORITY is an NS record(not a SOA) #this is a referral so we should disble DNS Express to allow for the subdomain to be recursed DNS::disable dnsx } } Tested this on version: 11.6Sanitize special characters in AD groups names
Problem this snippet solves: With APM, when you query Active Directory to retrieve the groups membership, if an AD group contains one or several special characters, the name of the group is considered not printable by APM and therefore is transformed in hex format. For example, if the name of an AD group is "Comptes_éditeurs" (in french), the APM session variable after AD query will be "session.ad.last.attr.memberOf = 0x436f6d707465735fc3a964697465757273". This is not convenient for usage in the APM policy. This snippet offers an iRule to transform "not printable" group names into printable group names by replacing all not printable chars by printable ones. Indeed, the previous example "Comptes_éditeurs" will be transformed by this snippet into "Comptes_editeurs", which will be printed properly and can be used as usual in an APM policy. How to use this snippet: Installation irule To make it works, you need to install the irule on the Virtual Server that publish your application with APM authentication. datagroup You need to create a strings datagroup named "dg_special_chars" that contains all the not printable chars you want to replace with their replacement char. The following datagroup will replace "é, è, ê, ë" with the normal "e" : c3a8 : 65 (è => e) c3a9 : 65 (é => e) c3aa : 65 (ê => e) c3ab : 65 (ë => e) The original special chars here (keys in the datagroup) are in hex format of UTF-8. You can have a look here http://www.utf8-chartable.de/ to find them. The replacement chars (values in the datagroup) are in hex format of standard ASCII. You can have a look here in the "ASCII printable characters" table http://www.rapidtables.com/code/text/ascii-table.htm. For example, if you need to replace "£" with "?", you need the following entry in your datagroup : c2a3 : 3f APM Policy In your APM policy you need to add a bloc "iRule Event" right after you call AD Query and before you test groups membership. In the "iRule Event" bloc, the "Custom iRule Event Agent" needs to be "clean_group_names". After this iRule Event, the sanitized groups names will be stored in the APM session variable "session.custom.ad.memberOf". To test groups membership, you can use the following condition in an "Empty" bloc : expr { [mcget {session.custom.ad.memberOf}] contains "CN=MY_GROUP, CN=Users, DC=MY_DOMAIN" } Code : when ACCESS_POLICY_AGENT_EVENT { if { [ACCESS::policy agent_id] eq "clean_group_names" } { set newMemberOf " | " set memberOf [ACCESS::session data get "session.ad.last.attr.memberOf"] set splited [split $memberOf "|"] # Loop through all groups foreach field $splited { # If the group starts with 0x, it is hexa, needs to be decoded if { $field starts_with " 0x" } { # remove spaces set trimed [string trim $field " "] # skip the 0x at the beginning set hex_data [string tolower [substr $trimed 2]] # Loop through all items in datagroup foreach item [class names dg_special_chars] { set new_char [class lookup $item dg_special_chars] # Replace the special char with a "normal" char regsub -all $item $hex_data $new_char hex_data } # Decode the hexa without special chars to string set groupStr [binary format H* $hex_data] # Concat the sanitize group name to the list set newMemberOf [concat $newMemberOf $groupStr " | "] # The group is not hexa, just concat the value as it is } elseif { $field ne "" } { set newMemberOf [concat $newMemberOf $field " | "] } } # Store the sanitize memberOf into a new session var ACCESS::session data set "session.custom.ad.memberOf" $newMemberOf } } Tested this on version: 12.1
