Showing results for 
Search instead for 
Did you mean: 
Login & Join the DevCentral Connects Group to watch the Recorded LiveStream (May 12) on Basic iControl Security - show notes included.

Troubleshooting connections to a node


Hi, I have a virtual server that a number of hosts connect to and can work successfully all day, however, there is one particular host that fails to connect.


From the CLI I can validate the working connections using show sys connections filtered down to the VS, the SNAT and then the node to view the connection to the end node. When I look at the same output from the perspective of the host unable to connect, all I can see is the connection to the VS and nothing onward from there and I'd like to find out why.


I think that the problem is on the side of the proxy server from the source host but I am hoping that there is a way on the F5 to pinpoint that.


Many thanks,





Sorry for my question,

As you are looking on network layer, have you tried to capture and see this traffic in the tcpdump utility?


Hi and thanks for your reply. Yes I used the tcpdump utility, however, it displayed nothing on screen. I just ran tcpdump host <IP address> From the cli.

I'm little confused now.

You couldn't see the client IP reaching VS address on any interface?

You should check current status and access permissions, vlan, etc to the specific client and node.


Anyway, this tcpdump may work to you see both client and server side communication filtering only by client IP:


tcpdump -vni 0.0:nnnp -s0 host <CLIENT IP>


I hope it helps.