Need help with insert true-client-ip to X-Forwarded-For rule on F5 LTM

[Prasad4u]

Hi,

Additional INFO: First of I will represent the access as it is done from the client to the F5

CLIENT --> Cloudflare --> F5 Service

• client try to access to the following hostname that is hosted by F5 : app.mydomain.com(1.2.3.4)
• Request will go to CloudFlare.
• CloudFlare will redirect user to F5 service (app.mydomain.com) at the same time it will cache the client's response for the future transaction.
• When CloudFlare will redirect user to F5 service (app.mydomain.com), CloudFlare will hide the real Client-IP and provide the CloudFlare IP.
• Instead of CloudFlare IP, We would like to grab the True-Client-IP and insert into X-Forwarder-For to see logs on the Server logs which is hosted behind the F5.

[Enes_Afsin_Al]

Hi Prasad4u,

iRule:

when HTTP_REQUEST {
	if { [HTTP::header exist True-Client-IP] } {
		# Client --> CloudFlare --> F5
		HTTP::header replace X-Forwarded-For [HTTP::header True-Client-IP]
	}
	else {
		# Client --> F5
		HTTP::header replace X-Forwarded-For [IP::client_addr]
	}
}

Additional note: In this scenario, don't use source_addr persistence.

[Prasad4u]

Hi Enes Afsin,

Greetings!!

After applying this irule, The VIP stopped working.

Could you please help us here.

[Enes_Afsin_Al]

Hi Prasad4u,

Can you investigate /var/log/ltm ?

Is there a log for this irule or another attached irule?

[Prasad4u]

Thanks for quick response Afsin. Will test and get back to you.