I was trying to access ubuntu server in virtualbox with linux mint in same computer, unfortunately i got error 'ssh: connect to host port 22: Connection timed out' .
And the best working solution that I found is;

1 - shutdown ubuntu from virtualbox and select ubuntu settings 
2 - Select Network Tab
3 - On the adapter 1, select Attached to and choose Bridged Adapter, click ok
3 - Now start ubuntu, type ifconfig n the second line you can see inet addr :
4 - Now open client's terminal and type ssh username@ip
5 - If you get any error, make sure you started ssh in ubuntu server, if not type in sudo service ssh start

here ;

username = the name which used in ubuntu server , example my username in ubuntu server is muhsin@dell, in this case just take muhsin only

ip = the ip that you just got with ifconfig cmmand,

now my command looks like ssh [email protected]

5 - Hit enter and now you're connected!