How can you tell what a server actually does? [closed]

Solution 1:

Unplug the ethernet cable and see who gets upset.

Seriously though, mystery machines like this create a lot of mental overhead for a team and often provide absolutely no business value. Talk to your boss, if no one knows what it does maybe no one cares what it does.

Solution 2:

This is a pretty broad question for the Serverfault format, but here is a good start:

• Check for running processes and those scheduled to run at system startup.
  • Review the running configuration of each.
  • Look into any defined data directories. (Maybe someone installed MySQL and turned it on, but there are no databases.)
• Check for scheduled tasks.
• Check the logs to see;
  • who has logged in recently (and ask them)
  • and to get an idea of what's been running.

You didn't mention the version, so I've omitted the specifics.

Solution 3:

There are a few things you could do to try and ascertain what's running on your system.

You can check which ports your server is listening on to get an idea of what's on there. A good command to use would be:

 [root@server ~]# netstat -tulpn
Active Internet connections (only servers)
Proto Recv-Q Send-Q Local Address               Foreign Address             Stat    e       PID/Program name
tcp        0      0 0.0.0.0:139                 0.0.0.0:*                   LIST    EN      1880/smbd
tcp        0      0 0.0.0.0:5666                0.0.0.0:*                   LIST    EN      1911/nrpe
tcp        0      0 0.0.0.0:22                  0.0.0.0:*                   LIST    EN      1759/sshd

As you can see from the example output above, it presents you with the protocol version (tcp or udp), the address that's being listened on, the port that's open and the program that's listening.

In the above truncated example (a server machine) you can see tcp ports 139, 5666, and 22 are listening. These resolve to samba, nrpe (Nagios agent) and ssh respectively, and is confirmed when you check the program that's listening on that port.

Additionally, you can check the list of daemons which are configured to start at boot, in order to do that, run: chkconfig --list | grep "3:on"

Example:

[root@server ~]# chkconfig --list | grep "3:on"
NetworkManager  0:off   1:off   2:on    3:on    4:on    5:on    6:off
acpid           0:off   1:off   2:on    3:on    4:on    5:on    6:off
sshd            0:off   1:off   2:on    3:on    4:on    5:on    6:off
sysstat         0:off   1:on    2:on    3:on    4:on    5:on    6:off
udev-post       0:off   1:on    2:on    3:on    4:on    5:on    6:off
vncserver       0:off   1:off   2:on    3:on    4:on    5:on    6:off
webmin          0:off   1:off   2:on    3:on    4:off   5:on    6:off
x2gocleansessions       0:off   1:off   2:on    3:on    4:on    5:on    6:off
.
.
.

or :

service --status-all