Q:

Can I use my Ubuntu for network administration?

Can you please name some tools that will help me analyze and administrate network and server?

A:

A very good tool to use is NMap. You can install it easily with :
sudo apt-get install nmap

Is is useful for security purposes to find if any unwanted ports on a computer are open, it can also be used to check IP addresses (I find it useful when the router resets and i
I need to find the IP address of my network printer.)
A command that would scan for a computers Operating System (-O), as well as script, version and trace route scanning.:
sudo nmap -A -O IP_ADDRESS

or for more informative output (verbose - -v):
sudo nmap -A -O -vvv IP_ADDRESS

For example, if I run this:
sudo nmap -A -O -vvv 192.168.1.6

it shows this for some Network Attached Storage (Closed):
Starting Nmap 6.40 ( http://nmap.org ) at 2013-12-22 16:32 GMT
Nmap scan report for 192.168.1.6
Host is up (0.00037s latency).
Not shown: 991 filtered ports
PORT     STATE  SERVICE      VERSION
21/tcp   closed ftp
22/tcp   open   ssh  
2049/tcp closed nfs
MAC Address: **:**:**:**:**:** (MANUFACTURER-OF-NETWORKING-HARDWARE)
Device type: general purpose
Running: Linux 2.6.X
OS CPE: cpe:/o:linux:linux_kernel:2.6
OS details: Linux 2.6.9 - 2.6.27
Network Distance: 1 hop

TRACEROUTE
HOP RTT     ADDRESS
1   0.37 ms 192.168.1.6

OS and Service detection performed. Please report any incorrect results at http://nmap.org/submit/ .
Nmap done: 1 IP address (1 host up) scanned in 13.24 seconds

This shows that it currently only has the ssh port open to access, on port 22, with the ftp and nfs ports available, but closed, on 21 and 2049 ports. An example for  use for this is that you could see if you had ssh remote access on a machine which you did not want to be accessed.
Yes, I have edited some sort-of-secret info out of the above output - including MAC Address: **:**:**:**:**:** (MANUFACTURER-OF-NETWORKING-HARDWARE)
There is also a graphical interface for Nmap you can use, called Zenmap
Hope this helps 

