F5 XC Distributed Cloud HTTP Header manipulations and matching of the client ip/user HTTP headers
1 . F5 XC distributed cloud HTTP Header manipulations In the F5 XC Distributed Cloud some client information is saved to variables that can be inserted in HTTP headers similar to how F5 Big-IP saves some data that can after that be used in a iRule or Local Traffic Policy. By default XC will insert XFF header with the client IP address but what if the end servers want an HTTP header with another name to contain the real client IP. Under the HTTP load balancer under "Other Options" under "More Options" the "Header Options" can be found. Then the the predefined variables can be used for this job like in the example below the $[client_address] is used. A list of the predefined variables for F5 XC: https://docs.cloud.f5.com/docs/how-to/advanced-security/configure-http-header-processing There is $[user] variable and maybe in the future if F5 XC does the authentication of the users this option will be insert the user in a proxy chaining scenario but for now I think that this just manipulates data in the XAU (X-Authenticated-User) HTTP header. 2. Matching of the real client ip HTTP headers You can also match a XFF header if it is inserted by a proxy device before the F5 XC nodes for security bypass/blocking or for logging in the F5 XC. For User logging from the XFF Under "Common Security Controls" create a "User Identification Policy". You can also match a regex that matches the ip address and this is in case there are multiple IP addresses in the XFF header as there could have been many Proxy devices in the data path and we want see if just one is present. For Security bypass or blocking based based on XFF Under "Common Security Controls" create a "Trusted Client Rules" or "Client Blocking Rules". Also if you have "User Identification Policy" then you can just use the "User Identifier" but it can't use regex in this case. To match a regex value in the header that is just a single IP address, even when the header has many ip addresses, use the regex (1\.1\.1\.1) as an example to mach address 1.1.1.1. To use the client IP address as a source Ip address to the backend Origin Servers in the TCP packet after going through the F5 XC (similar to removing the SNAT pool or Automap in F5 Big-IP) use the option below: The same way the XAU (X-Authenticated-User) HTTP header can be used in a proxy chaining topology, when there is a proxy before the F5 XC that has added this header. Edit: Keep in mind that in some cases in the XC Regex for example (1\.1\.1\.1) should be written without () as 1\.1\.1\.1 , so test it as this could be something new and I have seen it in service policy regex matches, when making a new custom signature that was not in WAAP WAF XC policy. I could make a seperate article for this 🙂F5 XC vk8s workload with Open Source Nginx
I have shared the code in the link below under Devcentral code share: F5 XC vk8s open source nginx deployment on RE | DevCentral Here I will desribe the basic steps for creating a workload object that is F5 XC custom kubernetes object that creates in the background kubernetes deployments, pods and Cluster-IP type services. The free unprivileged nginx image nginxinc/docker-nginx-unprivileged: Unprivileged NGINX Dockerfiles (github.com) Create a virtual site that groups your Regional Edges and Customer Edges. After that create the vk8s virtual kubernetes and relate it to the virtual site."Note": Keep in mind for the limitations of kubernetes deployments on Regional Edges mentioned in Create Virtual K8s (vK8s) Object | F5 Distributed Cloud Tech Docs. First create the workload object and select type service that can be related to Regional Edge virtual site or Customer Edge virtual site. After select the container image that will be loaded from a public repository like github or private repo. You will need to configure advertise policy that will expose the pod/container with a kubernetes cluster-ip service. If you are deploying test containers, you will not need to advertise the container . To trigger commands at a container start, you may need to use /bin/bash -c -- and a argument."Note": This is not related for this workload deployment and it is just an example. Select to overwrite the default config file for the opensource nginx unprivileged with a file mount."Note": the volume name shouldn't have a dot as it will cause issues. For the image options select a repository with no rate limit as otherwise you will see the error under the the events for the pod. You can also configure command and parameters to push to the container that will run on boot up. You can use empty dir on the virtual kubernetes on the Regional Edges for volume mounts like the log directory or the Nginx Cache zone but the unprivileged Nginx by default exports the logs to the XC GUI, so there is no need. "Note": This is not related for this workload deployment and it is just an example. The Logs and events can be seen under the pod dashboard and even the container/pod can accessed. "Note": For some workloads to see the logs from the XC GUI you will need to direct the output to stderr but not for nginx. After that you can reference the auto created kubernetes Cluster-IP service in a origin pool, using the workload name and the XC namespace (for example niki-nginx.default). "Note": Use the same virtual-site where the workload was attached and the same port as in the advertise cluster config. Deployments and Cluster-IP services can be created directly without a workload but better use the workload option. When you modify the config of the nginx actually you are modifying a configmap that the XC workload has created in the background and mounted as volume in the deployment but you will need to trigger deployment recreation as of now not supported by the XC GUI. From the GUI you can scale the workload to 0 pod instances and then back to 1 but a better solution is to use kubectl. You can log into the virtual kubernetes like any other k8s environment using a cert and then you can run the command "kubectl rollout restart deployment/niki-nginx". Just download the SSL/TLS cert. You can automate the entire process using XC API and then you can use normal kubernetes automation to run the restart command F5 Distributed Cloud Services API for ves.io.schema.views.workload | F5 Distributed Cloud API Docs! F5 XC has added proxy_protocol support and now the nginx container can work directly with the real client ip addresses without XFF HTTP headers or non-http services like SMTP that nginx supports and this way XC now can act as layer 7 proxy for email/smpt traffic 😉. You just need to add "proxy_protocol" directive and to log the variable "$proxy_protocol_addr". Related resources: For nginx Plus deployments for advanced functions like SAML or OpenID Connect (OIDC) or the advanced functions of the Nginx Plus dynamic modules like njs that is allowing java scripting (similar to F5 BIG-IP or BIG-IP Next TCL based iRules), see: Enable SAML SP on F5 XC Application Bolt-on Auth with NGINX Plus and F5 Distributed Cloud Dynamic Modules | NGINX Documentation njs scripting language (nginx.org) Accepting the PROXY Protocol | NGINX Documentation
