Linux renew ip command

The -r flag explicitly
releases the current lease, and once the lease has been released, the
client exits. For example, open terminal and type the command:

$ sudo dhclient -r

Now obtain fresh IP:

$ sudo dhclient

There is no need to restart network service. Above command should
work with any Linux distro such as RHEL, Fedora, CentOS, Ubuntu and
others. On a related note you can also try out the following commands:

# ifdown eth0

# ifup eth0

# /etc/init.d/network restart

OR

# /etc/init.d/networking restart