We will look at tools that can be used to enumerate Linux based systems.

finger
Returns information about a user on the system

finger -l u1
Login: u1          			Name: u1
Directory: /home/boris              	Shell: /bin/bash
On since Wed Sep 28 14:23 (EDT) on tty8 from :0
    6 days 22 hours idle
On since Wed Oct  5 12:56 (EDT) on pts/3 from :0
   2 seconds idle
No mail.
No Plan.
$ finger
Login     Name       Tty      Idle  Login Time   Office     Office Phone
u1     u1      tty8       6d  Sep 28 14:23 (:0)
u1     u1      pts/3          Oct  5 12:56 (:0)

-b removes home directory and shell
-f removes header information
-w removes full name
-l returns the list of users

showmount
Lists and identifies the shared directories on a given system
-a print all remote mounts
-d lists directories that have been remotely mounted by clients
-e prints list of shared file systems

showmount -e 192.168.0.200
Export list for 192.168.0.200:
/volume1/backup_data   192.168.0.19
/volume1/backup_images 192.168.0.30

rcpinfo

enum4linux