SSH

Tunneling to socks proxy

From here: ssh-tunnel-socks-proxy

In short:

ssh -D 9999 username@ip-address-of-ssh-server
# Then set in Firefox to use a SOCKS proxy: “localhost", port 9999

Tunneling between any two ports

Say, you want to read a remote server web page, but there is only ssh port open on the server. If you have a valid user account to the server, then you can create a tunnel, like this:

ssh -f user@server.com -L 8080:server.com:80 -N

Now you can enter the following in your browser: http://server.com:8080

Or in general, -f means sit in background and -N menas do not execute any command:

ssh -f user@server.com -L my-local-port:server.com:server-port -N

Tunneling OpenVPN connection

Source: https://redfern.me/tunneling-openvpn-through-ssh/

1. Set the OpenVPN server config file to use TCP rather than UDP. This is done by changing the line proto udp to proto tcp in the server config file (normally located at /etc/openvpn/server.conf).
2. Set the OpenVPN client config file to use TCP rather than UDP. You can do this by changing the line proto udp to proto tcp-client in the client config file.
3. Change the OpenVPN client config to connect to localhost rather than the remote server address. This is done by changing the “remote” line of the server to remote localhost 1194
4. Create an SSH tunnel between the client machine and the OpenVPN Server, and forward from remote:1194 to localhost:1194. This can be done by running the command on the client machine (assuming you’re running Linux/Unix with the OpenSSH client binary installed):

ssh user@server -L 1194:localhost:1194 

All being well, after making those config file changes and creating your SSH tunnel, you’ll be able to tunnel OpenVPN through SSH.

Removing a key from the known hosts file

Note, you may run this for the hostname of the "old" computer and for the IP address.

ssh-keygen -R hostname

Using ssh with a private/public key

If you are using svn+ssh or just want automatic login without typing the password whenever using ssh, you may want to consider setting up public-private key authentication between the client and server machine. The server will have the public key, and the client will have the private key. This is how to set it up:

On the client: generate the public/private key pair

 cd ~/.ssh
 ssh-keygen -t dsa 

Copy the public key to your server, and add to ~/.ssh/authorized_keys file, like this:

 ssh-copy-id remote-machine

...or:

 ssh remote-machine 'cat >> .ssh/authorized_keys' < .ssh/id_dsa.pub

...or, if you prefer the long way (smile), do it like this:

 scp ./id_dsa.pub user@myserver.com:
 ssh user@myserver.com
 myserver>  cat id_dsa.pub >> .ssh/authorized_keys
 myserver>  rm id_dsa.pub
 myserver>  logout

Remember to check that your .ssh/ directory and files in there are not public readable, otherwise someone may steal your private key and get access to your server!

Done!

Turning the keys and identities on and off

You may want to use the following commands or even define aliases as below. Note, ssh -t <seconds> sets timeout for the open key. In the example below 10800 = 3 hours.

alias keyon="ssh-add -t 10800"
alias keyoff='ssh-add -D'
alias keylist='ssh-add -l'

Other links and info

• http://sial.org/howto/openssh/publickey-auth/