How do I install SSH in Ubuntu?

Question

I am using Ubuntu 12.04 and am trying to install SSH using the below command:

[root@avi ~]# sudo apt-get install ssh

However I am getting this error:

Reading package lists... Done
Building dependency tree     
Reading state information... Done
Package ssh is not available, but is referred to by another package.
This may mean that the package is missing, has been obsoleted, or
is only available from another source
However the following packages replace it:

  openssh-client ssh-askpass-gnome

E: Package ssh has no installation candidate

I also tried this command:

[root@avi ~]# sudo apt-get install openssh-server

How can I install it successfully?

Solution

I noticed this in what you posted:

However the following packages replace it:

  openssh-client ssh-askpass-gnome

The command to use open-ssh that is already installed (you proved it with what you provided) is simply

ssh (host IP or host URL)

Comments

[Izzy]

In short: Some other package depends on ssh ("is referred to by another package"), but no source provides it ("ssh has no installation candidate"). Please do an apt-cache depend ssh to figure out which package causes the problem. Additionally, please state whether you use some 3rd party repositories (e.g. ppas) which might have introduced the troublemaker, and if so, which one(s).

[Prerak Diwan]

Everett. Please don't edit the OP's question to add to your answer. Question edits or for formatting, clarification, and general cleanup. Not to help you answer. If you need to quote the OP do as I have to your answer. Happy Answering :)

[Everett]

Honestly, thank you for pointing that out, I will make more judicious use of it.