[FIXED] How to get IP of outside connection using telnet, or perhaps misconfiguration of memcached allowed ip's

Issue

Server A with memcached, Server B needs to use memcached. If I leave memcached open to all ips (default), Server B can:

telnet server.a.etc 11211 

and get in. If I ping server B, I get an ip, 153.353.234.23 (example), and I put that in my memcached options

OPTIONS="-l 153.353.234.23"

restart and now server b can't connect over telnet any longer. I assume this is because perhaps it is using a different ip address for this connection? Some other error? Either way, I'd like to be able to see the ip of server B when it connects.

I enabled memcached logging

-vvv >var/log/memcached.log 2>&1

and I see logs getting generated, but not the ip addresses of connecting machines.

Solution

with memcached -l you are instructing the memcached server to bind on a specific IP address of the server. This is useful if you want memcached to accept data on a specific IP or network interface on your server node. You can leave the default to make memcached bind on any IP address of the server (0.0.0.0 on IPv4).

I don't think memcached has a command switch to login the source IP. You can use the command

netstat -natp | grep 11211 | grep ESTABLISHED

on a linux system to get the established connections to memcached and the IPs of the clients.

Answered By - dAm2K

Answer Checked By - Mary Flores (PHPFixing Volunteer)