In Raspian Jessie it should be activated all ready.
For activating the SSH connection open

$ sudo raspi-config

In 8. Advanced Options you can activate SSH.

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Look up your gateway:

$ netstat -r -n

Find you IP address: $ ifconfig

$ ip addr

Give the Raspberry Pi a static IP address. Open the interfaces file:

$ sudo nano /etc/network/interfaces

Add these lines after “face eth0 inet dhcp”:

   auto eth0:1
   iface eth0:1 inet static
     address 192.168.0.199
     netmask 255.255.255.0
     gateway 192.168.0.1
     

Restart ethernet

$ sudo ifdown eth0:1
$ sudo ifup eth0:1

One can login with:

$ ssh pi@192.168.0.111

or with XWindows support:

$ ssh -XY pi@192.168.0.111

PW: raspberry