Hi,
the output in the /var/log/messages is what you get when you run
[root#Server]# dhclient
from the command line.The command line hangs if you are connected via ssh,because it connects to DHCP server.But why was this done?It probably is not in some kind of monthly script,because it would have been launched earlier,and you say that this is running for 80 days.
Have you checked /var/spool/root directory for custom made crons?
Have you checked command line history?Other than root,which account has bash login enabled?You might see those account in /etc/passwd,log as them and check command line history,to see if it contains dhclient.
There might be some kind of startup or init.d script that runs dhclient. In that case, it has to be somewhere in /etc directory. You can launch a full-text search of /etc/ directorywith:
cd /etc
grep -lir "dhclient" *
...and wait....
...and wait...
...and eventually the names of files (if any) containing the text "dhclient" will pop out. I hope it will,because if it doesn't,that means somebody has messed up with your server.Services don't start by themself in Linux...