Linux – persistent SSH connection while connecting to VPN

linuxnetworkingsshvpn

I have a Linux machine on the intranet which I can only access via SSH, this machine needs to connect to a VPN using openconnect however when I do that I get disconnected from the SSH since the intranet's IP is no longer valid.

I can reconnect to it from within the VPN using the IP it got assigned but that IP changes everytime the VPN is connected, I don't have control over any othe networks only this machine.

is there a way to keep the SSH connection alive while connecting to the VPN? thanks.

openconnect requires a –script argument which takes a script to configure routing, without it the connection succeeds but no names are resolved and the intranet's IP remains valid.

I'm currently using Ubuntu's default /etc/vpnc/vpnc-script (pasted here) I'm good with shell scripting but I know very little about networking, if I have to modify that I'll need some reference about what or how to change it.

Best Answer

is there a way to keep the SSH connection alive while connecting to the VPN?

No. That system's routing changes dramatically when you connect to the VPN, which breaks all established TCP sockets.

You should look into using a terminal multiplexer like screen or tmux in your ssh session - that way you can have a persistent shell that you can re-connect to.

Related Solutions

Ssh – How to automate SSH login with password

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.

SSH – Bad Owner or Permissions on ~/.ssh/config

I needed to have rw for user only permissions on config. This fixed it.

chmod 600 ~/.ssh/config

As others have noted below, it could be the file owner. (upvote them!)

chown $USER ~/.ssh/config

If your whole folder has invalid permissions here's a table of possible permissions:

Path	Permission
.ssh directory (code)	0700 (drwx------)
private keys (ex: `id_rsa`) (code)	0600 (-rw-------)
`config`	0600 (-rw-------)
public keys (*.pub ex: `id_rsa.pub`)	0644 (-rw-r--r--)
`authorized_keys` (code)	0644 (-rw-r--r--)
`known_hosts`	0644 (-rw-r--r--)

Sources:

openssh check-perm.c
openssh readconf.c
openssh ssh_user_config fix_authorized_keys_perms

Best Answer

Related Solutions

Ssh – How to automate SSH login with password

SSH – Bad Owner or Permissions on ~/.ssh/config

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