Change MTU size in Linux

Maximum Transmission Unit(MTU), the largest physical packet size, measured in bytes, that a network can transmit. Any messages larger than the MTU are divided into smaller packets before being sent .
By optimizing the MTU setting you can gain substantial network performance.
In IPv4 the values range between 576 and 1500 bytes being the max size.

The general syntax is: ifconfig "interface" mtu "size"

For example:ifconfig eth0 mtu 1420


Will change MTU to 1420 bytes.

For permanent change, you can add the MTU parameter into your interface configuration file,
For example in Debian the configuration will look like this:

iface eth0 inet static
address 192.168.0.100
network 192.168.0.0
gateway 192.168.0.254
netmask 255.255.255.0
mtu 1420