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SSH

SSH stands for Secure Shell Protocol, which enables you to connect to remote server safely.

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Login to remote server

ssh <username>@<host>

Before you login in, you need to generate keys for ssh connection:

Keys

ssh-keygen -t rsa -b 4096
You will get two keys, a public one and a private one.

  • public key : ~/.ssh/id_rsa.pub
  • private key : ~/.ssh/id_rsa

Warning

Don't share your private key with others.

What you need to do is just add you local public key to ~/.ssh/authorized_keys on host server.

File transfer

Suppose you are using a local machine:

Donwload files from remote host to local machine 

scp <username>@<host>:remote_path local_path

Upload files from local machine to remote host

scp local_path <username>@<host>:remote_path

Info

-r : copy recursively. This option is needed when you want to transfer an entire directory.

Example

Copy the local work directory to remote home directory 

$ scp -r /home/gwaslab/work gwaslab@remote.com:/home/gwaslab

SSH Tunneling

Quote

In this forwarding type, the SSH client listens on a given port and tunnels any connection to that port to the specified port on the remote SSH server, which then connects to a port on the destination machine. The destination machine can be the remote SSH server or any other machine. https://linuxize.com/post/how-to-setup-ssh-tunneling/

-L : Local port forwarding

ssh -L [local_IP:]local_PORT:destination:destination_PORT <username>@<host>

other SSH options

  • -f : send to background.
  • -p: port for connenction (default:22).
  • -N : not to execute any commands on the remote host. (so you will not open a remote shell but just forward ports.)