Forum Discussion

Nimbostratus

Jul 29, 2015

PUBLIC FQDN

Hello Experts My scenario is some what like, we have user machines which will be trying to access an internal portal page, which will be resolved to internal IP. This IP will be used as VIP on F...

Historic F5 Account

Jul 29, 2015

I would recommend using

tcpdump

to look at the traffic flow:

SOL411: Overview of packet tracing with the tcpdump utility

and check /var/log/ltm to ensure that there are no errors. Since you have the http profile applied, the flow should look like this in a tcpdump:

 CLIENT                     BIG-IP                  SERVER
         --- SYN      --->    |
         <-- SYN/ACK  ---     |
         --- ACK      --->    |
         ---  --->    |
                              +  --- SYN      --->
                              + <--- SYN/ACK  ---
                              +  --- ACK      --->
                              +  ---  --->

where REQHDR are the request headers. On the second half (between the BIG-IP and the SERVER), the source address will be the SNAT source address (172.16.254.50).

Having said all of that, the SNAT source address on the BIG-IP (172.16.254.50) must be able to reach the public addresses (since it's an RFC 1918 address, I assume it is subject to further address translation somewhere else?) and there must be a route back to that address.

Vishal_Bhugra_1
Nimbostratus
Jul 30, 2015
I did the packet capture, but I do see the HTTP header, But I am not sure how can How can I capture the server side. I have only one vlan and a default route. The SNAT SOURCE 172.16.254.50 is behind the Firewall, where it is getting NAT. Will it work ?