Linux – Ubuntu 10.04 SSH becomes unresponsive

Use mtr to check the network. Try a command like mtr -i 15 remotehost. Leave this running in a window, or use screen so you can detach. It should catch any problems with the network. Packet loss is typically 0% on most of my systems.

EDIT: What does the output of arp -n show for your IP address before and after ssh drops. You may want to try this on another server on the same subnet. There should be only one HW address for the IP address and it should not change. If it does you have an IP address conflict.

Don't use a password. Generate a passphrase-less SSH key and push it to your VM.

If you already have an SSH key, you can skip this step… Just hit Enter for the key and both passphrases:

$ ssh-keygen -t rsa -b 2048
Generating public/private rsa key pair.
Enter file in which to save the key (/home/username/.ssh/id_rsa):
Enter passphrase (empty for no passphrase):
Enter same passphrase again:
Your identification has been saved in /home/username/.ssh/id_rsa.
Your public key has been saved in /home/username/.ssh/id_rsa.pub.

Copy your keys to the target server:

$ ssh-copy-id id@server
id@server's password:

Now try logging into the machine, with ssh 'id@server', and check-in:

.ssh/authorized_keys

Note: If you don't have .ssh dir and authorized_keys file, you need to create it first

to make sure we haven’t added extra keys that you weren’t expecting.

Finally, check to log in…

$ ssh id@server

id@server:~$

You may also want to look into using ssh-agent if you want to try keeping your keys protected with a passphrase.