To run a command as administrator (user "root"), use "sudo <command>".
See "man sudo_root" for details.

ubuntu@ubuntu:~$ sudo apt-get install ssh
Reading package lists... Done
Building dependency tree       
Reading state information... Done
The following extra packages will be installed:
  openssh-server
Suggested packages:
  rssh molly-guard
The following NEW packages will be installed:
  openssh-server ssh
0 upgraded, 2 newly installed, 0 to remove and 0 not upgraded.
Need to get 258kB of archives.
After unpacking 737kB of additional disk space will be used.
Do you want to continue [Y/n]? y
Get:1 http://archive.ubuntu.com feisty/main openssh-server 1:4.3p2-8ubuntu1 [257kB]
Get:2 http://archive.ubuntu.com feisty/main ssh 1:4.3p2-8ubuntu1 [1086B]       
Fetched 258kB in 7s (36.4kB/s)                                                 
Preconfiguring packages ...
Selecting previously deselected package openssh-server.
(Reading database ... 94088 files and directories currently installed.)
Unpacking openssh-server (from .../openssh-server_1%3a4.3p2-8ubuntu1_powerpc.deb) ...
Selecting previously deselected package ssh.
Unpacking ssh (from .../ssh_1%3a4.3p2-8ubuntu1_all.deb) ...
Setting up openssh-server (4.3p2-8ubuntu1) ...
Creating SSH2 RSA key; this may take some time ...
Creating SSH2 DSA key; this may take some time ...
 * Restarting OpenBSD Secure Shell server...                             [ OK ] 

Setting up ssh (4.3p2-8ubuntu1) ...

ubuntu@ubuntu:~$