Could not find id_rsa.pub

Question

I am under cloud Ubuntu 12.04.5 LTS.
And I couldn't find id_rsa.pub file.

$ ls -ll ~/.ssh 
total 12
-rw------- 1 root root 4435 Jul 22 11:15 authorized_keys
-rw-r--r-- 1 root root 2660 Jul 22 15:45 known_hosts

In authorized_keys file there are public keys of hosts that can access to the server.
In known_hosts file there are many repeated chunks of code:

|1|fg5CCFQU2d3/Ut6EFN8SivyYZpg=|CMkxOukPDy50bualN6lAiobvQc4= ecdsa-sha2-nistp256 AAAAE2VjZHNhLXNoYTItbmlzdHAyNAAAAIbmlzdHAyNTYAAABBBLPpEXdAdrPJgZuO+lowXVQbyCbzjVLxshDNFlAINvdlMzu3GwgEI/UPGZjTq+n4iBq702Ho7vshj0UtbX9IQDA=
|1|kSgZ7ya8jCLgz6Uga0wlOzcclSY=|63ZjaYQdxQuBzFZn4sDxoC/zAxE= ecdsa-sha2-nistp256 AAAAE2VjZHNhLoYTItbmlzdHAyNTYAAAAIbmlzdHAyNTYAAABBBLPpEXdAdrPJgZuO+lowXVQbyCbzjVLxshDNFlAINvdlMzu3GwgEI/UPGZjTq+n4iBq702Ho7vshj0UtbX9IQDA=

I couldn't figure out where is the server id_rsa.pub.

Solution

You need to generate your private and public key:

ssh-keygen -t rsa 

And to add your key as an authorized key on the server side:

ssh-copy-id <server hostname/ip address>

Comments

[Wilf]

This I think needs to be done on the client machine, and then sent to the server with something like cat .ssh/id_rsa.pub | ssh USERNAME@IP_ADDRESS 'cat >> .ssh/authorized_keys' (on linux atleast)

[mgor]

Updated answer with an easier way to add your key on the server side.

[Lesha Pipiev]

Guys, I am on the server side. An I couldn't find the public key. Does it mean I should generate it?

[Wilf]

Yeah (i think) if you want to access a server without a pass from a client you need to generate the private and public keys on the client, then copy the public key to the server's .ssh/authorized_keys file

[mgor]

In that case, run ssh-copy-id on your client machine to add your public key I your users authorized_keys on the server. The server side does not necessarily need a public and private key in the .ssh directory.