Shell is a program to log into another computer over a network, to
execute commands in a remote machine, and to move files from one
machine to another. It provides strong authentication and secure
communications over unsecured channels.
It is intended as a replacement for telnet, rlogin,
rsh, and rcp.
The SSH2 replacement for FTP, is
sftp. The current recommended SSH version is
The telnet and ftp programs have a serious security
problem--when you type your password is sent in clear text over the
wire, which means that any other computer listening on that wire can
potentially read your password. Hackers make use of this flaw by
installing "sniffer" programs that
specifically listen for passwords from any computer on the network.
A more secure alternative to telnet or rsh,
rcp, or rlogin, is to use the Secure
Shell (SSH) protocol, which both encrypts the connection and uses
digital signatures to positively identify the host at the other end
of the connection. Some servers in HUJI already require a Secure
Shell connection. In the future connections via telnet from networks
outside the University will not be allowed (rlogin is already