Bring the network interface up or down in linux

It is possible to bring up or bring down the network interface with following command
To bring down eth1
ifdown eth1
To bring up eth1
ifup eth1

How to disable root SSH login

[root@root ~]# vi /etc/ssh/sshd_config
Change this line:
#PermitRootLogin yes
Edit to this:
PermitRootLogin no
Restart ssh service to change the setting
service ssh restart