http://ru.wikipedia.org/wiki/Telnet

http://en.wikipedia.org/wiki/Remote_shell

root@gate:~# apt-get install telnetd

root@gate:~# cat /etc/inetd.conf

[gate:~] # cat /etc/inetd.conf

...
telnet stream  tcp     nowait  root    /usr/libexec/telnetd    telnetd
...

root@gate:~# apt-get install rsh-server

root@gate:~# cd /lib/security

root@gate:/lib/security# ln -s pam_rhosts.so pam_rhosts_auth.so
root@gate:/lib/security# ln -s pam_unix.so pam_unix_session.so
root@gate:/lib/security# ln -s pam_unix.so pam_unix_acct.so

[gate:~] # cat /etc/inetd.conf

...
shell  stream  tcp     nowait  root    /usr/libexec/rshd       rshd
...

student@client1:~# apt-get install rsh-client

[gate:~] # cat /etc/inetd.conf

...
login   stream  tcp     nowait  root    /usr/libexec/rlogind    rlogind
...

gate# cat ~user1/.rhosts

client1 root
client1

client1$ rsh gate "uname -a"

client1$ cat /etc/hosts | rsh gate "cat > hosts.bak"

client1$ rcp /etc/hosts gate:hosts.bak

client1# rlogin gate

client1# rsh -l user1 gate "uname -a"

client1# rcp /etc/shadow user1@gate:
client1# rcp /etc/master.passwd user1@gate:

client1# cd /
client1# tar -cvf - etc/ | rsh -l user1 gate "cat > etc.tar"