Logging outgoing SNAT List connections

I´m not sure, if I got your question right. If you are talking about incoming connections to be balanced to a pool of local servers and SNAT is applied somehow, you can use an iRule as this one (second log):

when SERVER_CONNECTED {
     log clientside connection details to /var/log/ltm
    log local0. "Clientside connection: [clientside {IP::remote_addr}]:[clientside {TCP::remote_port}] to [clientside {IP::local_addr}]:[clientside {TCP::local_port}]"
     log serverside connection details to /var/log/ltm
    log local0. "Serverside connection: [IP::local_addr]:[TCP::local_port] to [IP::remote_addr]:[TCP::remote_port]"
}

Or are you talking about so called default SNATs?

I guess, a wildcard virtual server is listening on the internal VLAN and forwards outgoing connection, right? In this case the iRule above assigned to this virtual server will log the internal server in the first log statement. The second log statement lists the used SNAT address as local address. Feel free to combine the log statements into a single one.

An alternative approach for just monitoring the current open connection would be the "tmsh show sys conn" command.

 tmsh show sys conn cs-client-addr 10.131.131.201
Sys::Connections
10.131.131.201:50266  10.131.131.141:80  10.131.131.131:50266  10.131.131.121:80  tcp  1  (tmm: 0)  none
Total records returned: 1

Client 10.131.131.201 tries to connect and gets SNATed by 10.131.131.131 when being connected to 10.131.131.121.

what Stephan suggested is to use virtual server (e.g. wildcard ip forwarding virtual server) with snatpool instead of snat list. so, you can setup logging in irule and assign to the virtual server.

what Stephan suggested is to use virtual server (e.g. wildcard ip forwarding virtual server) with snatpool instead of snat list. so, you can setup logging in irule and assign to the virtual server.