1) First try pining your own IP address to see if your IP address is set properly, syntax is:
If your IP address is 126.96.36.199 then try:
# ping 188.8.131.52
Tip use ifconfig command to see IP address for eth0 or any other interface.
2) Try pinging neighboring machines IP addresses:
# ping 192.168.1.2
# ping 184.108.40.206
If you need to setup/configure network or connecting to the network under Linux use following tools:
Under Red Hat use neat OR system-config-network (Fedora core) command
Uder Debian Linux use network-admin command.
You can also start above command from GUI. Using above GUI tools you should able to configure DNS, hosts, IP address etc. For more information see:
List of LINUX troubleshooting commands/tools part # 1