02 April 2013

Top 10 Networking Commands in Linux

There are many network commands linux supports but there are only a few commands that explore the major things in a network. There are 10 such networking commands in Linux to explore the routing, packets, etc.
if you want to know about the commands use "man commandname" (without Quotes)
Command 1:
# ifconfig
you may use the options to configure ifconfig -v (for showing the verbose mode)
command to configure the given network interface (wlan0, eth0, etc)
Command 2 :
# ping 172.16.1.10

To send ICMP, Echo request to hosts

Here is the output
PING 172.16.1.10 (172.16.1.10) 56(84) bytes of data.
64 bytes from 172.16.1.10: icmp_req=1 ttl=128 time=0.735 ms
64 bytes from 172.16.1.10: icmp_req=2 ttl=128 time=0.871 ms

--- 172.16.1.10 ping statistics ---

2 packets transmitted, 2 received, 0% packet loss, time 999ms
rtt min/avg/max/mdev = 0.735/0.803/0.871/0.068 ms
Command 3: 
traceroute domainname or IP Address
print the route packets trace to network host
Ex: 
traceroute www.vit.ac.in
See the image below for output
Command 4: 
route -n
 show / manipulate the IP routing table
it displays the kernel routing table with the default address and next hop address as given below
Output:
Kernel IP routing table
Destination     Gateway         Genmask         Flags Metric Ref    Use Iface
0.0.0.0         172.16.0.10     0.0.0.0         UG    0      0        0 wlan0
169.254.0.0     0.0.0.0         255.255.0.0     U     1000   0        0 wlan0
172.16.0.0      0.0.0.0         255.255.192.0   U     9      0        0 wlan0
172.16.29.0     0.0.0.0         255.255.255.0   U     0      0        0 vmnet8
172.16.33.0     0.0.0.0         255.255.255.0   U     0      0        0 vmnet1
Command 5: 
# nslookup domainname
it querys Internet name servers interactively
Command 6: 
telnet ipaddress
user interface to the TELNET protocol
it uses to connect to other machines using the TELNET protocol
Command 7: 
ssh ipaddress
OpenSSH SSH client (remote login program)
the usage is
ssh username@ipaddress
you need to enter the password of the user
Ex: ssh pradeepkumar@172.16.49.132
if you want to use it with graphical interface, "ssh -X pradeepkumar@172.16.49.132"
Command 8: 
host ipaddress or domainname (DNS lookup utility)
Here is the output for the following 
host nsnam.com
Command 9: 
dig ipaddress mx   (DNS lookup utility (domain information groper))
dig nsnam.com mx (mx for mail exchange)
Command 10: 
netstat -a
Print network connections, routing tables, interface statistics, masquerade connections, and multicast memberships