SSH Port Forwarding – How to Clear Local SSH Port for Remote Forwarding

portssh

I'm using ssh forwarding local port to a bastion server(10.20.30.40), connect to remote RDS database.

ssh -i ~/.ssh/id_rsa -f -N -L 5432:db1.cluster-1.region.rds.amazonaws.com:5432 10.20.30.40 -v
...
Authenticated to 10.20.30.40 ([10.20.30.40]:22).
debug1: Local connections to LOCALHOST:5432 forwarded to remote address db1.cluster-1.region.amazonaws.com:5432
debug1: Local forwarding listening on ::1 port 5432.
debug1: channel 0: new [port listener]
debug1: Local forwarding listening on 127.0.0.1 port 5432.
debug1: channel 1: new [port listener]
debug1: Requesting [email protected]
debug1: forking to background
debug1: Entering interactive session.
debug1: pledge: network
debug1: client_input_global_request: rtype [email protected] want_reply 0

The 5432 on local port will be used. If create a new forwarding

ssh -i ~/.ssh/id_rsa -f -N -L 5433:db1.cluster-1.region.rds.amazonaws.com:5432 10.20.30.40 -v

The 5433 port will be used.

If start 5432 in a new terminal, it will be failed because already in use.

Authenticated to 10.20.30.40 ([10.20.30.40]:22).
debug1: Local connections to LOCALHOST:5432 forwarded to remote address db1.cluster-1.region.rds.amazonaws.com:5432
debug1: Local forwarding listening on ::1 port 5432.
bind [::1]:5432: Address already in use
debug1: Local forwarding listening on 127.0.0.1 port 5432.
bind [127.0.0.1]:5432: Address already in use
channel_setup_fwd_listener_tcpip: cannot listen to port: 5432
Could not request local forwarding.
debug1: Requesting [email protected]
debug1: forking to background
debug1: Entering interactive session.
debug1: pledge: network
debug1: client_input_global_request: rtype [email protected] want_reply 0

How to release these ports connection?

Best Answer

The port is going to be blocked as long as your SSH session is active. If you weren't spawning it into the background with the -f parameter you could just log out or hit ctrl-c, you can't do that with the session in the background.

You can list running processes with ps. Then you kan kill the process.

$ ps  -af |grep ssh
username    2113    1822  0 10:19 pts/0    00:00:00 ssh -L 5433:db1.cluster-1.region.rds.amazonaws.com:5432 host
$ kill 2113

For Git Bash

If you are running msysgit (I am assuming you are) and are looking to run Git Bash (I recommend it over TortoiseGit, but I lean to the CLI more than GUI now), you need to figure out what your home directory is for Git Bash by starting it then type pwd (On Windows 7, it will be something like C:\Users\phsr I think). While you're in Git Bash, you should mkdir .ssh.

After you have the home directory, and a .ssh folder under that, you want to open PuTTYgen and open the key (.ppk file) you have previously created. Once your key is open, you want to select Conversions -> Export OpenSSH key and save it to HOME\.ssh\id_rsa. After you have the key at that location, Git Bash will recognize the key and use it.

Note: Comments indicate that this doesn't work in all cases. You may need to copy the OpenSSH key to Program Files\Git\.ssh\id_rsa (or Program Files (x86)\Git\.ssh\id_rsa).

For TortoiseGit

When using TortoiseGit, you need to set the SSH key via pacey's directions. You need to do that for every repository you are using TortoiseGit with.

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.

Best Answer

Related Solutions

Git for Windows – How to Tell Git Where to Find Private RSA Key

For Git Bash

For TortoiseGit

Ssh – How to automate SSH login with password

Related Topic