Networking - SSH

ssh is a program for logging into a remote machine and for executing commands on a remote machine. It is intended to replace rlogin and rsh, and provide secure encrypted communications between two untrusted hosts over an insecure network. ssh connects and logs into the specified hostname. The user must prove his/her identity to the remote machine using one of several methods depending on the protocol version used:

The performance of ssh is as like telnet except we can't login as root user by telnet. But by the ssh server we can login as root user in the remote system. All necessary rpm to install ssh are given below which rpms come with Linux installation CD,

[root@www RPMS]# rpm -ivh openssh-3.6.1p2-34.i386.rpm

ð This rpm is necessary for server side.

[root@www RPMS]# rpm -ivh openssh-server-3.6.1p2-34.i386.rpm

ð This rpm is necessary for server side.

[root@www RPMS]# rpm -ivh openssh-clients-3.6.1p2-34.i386.rpm

ð This rpm is necessary for only client side.

[root@www RPMS]# service sshd start

Starting sshd: [ OK ]

ð Both client and server sides need to start ssh service. Now client computer can be used to login to remote system.




[root@www root]# ssh


[root@www root]# ssh's password:

Last login: Mon Jun 27 14:31:57 2005 from

[root@mail root]#

ð By default, it logins as which user are using this ssh service. To login as normal user give the command as following syntax,

ssh @


[root@www root]# ssh sumon@


[root@www root]# ssh's password:

[sumon@mail sumon]$ ls

[root@www root]# who

root tty1 Jun 27 13:30

root tty2 Jun 27 14:24

root pts/4 Jun 27 14:27

root pts/6 Jun 27 14:28

root pts/10 Jun 27 14:31 (

sumon pts/11 Jun 27 14:37 (

ð By who command we can ensure that which remote system is being accessed.

[sumon@mail sumon]$ exit

Connection to closed.

[root@www root]#

ð To logout from remote system we can use exit command.