I moved a vmware host into a different vlan and suddenly people could not connect to it from a special jump box that was created to access servers in that particular vlan. I check a bunch of places that I could think of then asked my co-worker.
This is a centos 5.x linux server and we checked the following:
And finally found: /etc/hosts.deny which had a line that specified:
sshd : ALL EXCEPT 10.xxx.xx.x/255.xxx.xxx.xxx
We added an entry for the new subnet, saved and closed the file and voila.
Thanks to Rachael Stewart for finding this one. It seems this is an older way of securing the server before they started using iptables.