SSH, scp and rsync

Connecting, keys, ~/.ssh/config, port forwarding, jump hosts and copying files.

Connecting

Connect to a server

ssh <user>@<host>

Connect on a non-standard port

ssh -p <port> <user>@<host>

Connect with a specific key

ssh -i ~/.ssh/<ssh_key> <user>@<host>

Run a single command remotely

ssh <user>@<host> 'uptime && df -h'

Debug connection problems

ssh -vvv <user>@<host>

Generate a key

ssh-keygen -t ed25519 -C "<email>"

Copy your public key to a server

ssh-copy-id <user>@<host>

Add a key to the agent

ssh-add ~/.ssh/<ssh_key>

Remove a host from known_hosts

ssh-keygen -R <host>

Needed after a server was reinstalled and the “host key changed” warning appears.

Key fingerprint

ssh-keygen -lf ~/.ssh/<ssh_key>.pub

Local forward: remote DB on localhost:5433

ssh -N -L 5433:localhost:5432 <user>@<host>

-N means no remote command, just the tunnel.

Forward to a host reachable only from the serveradvanced

ssh -N -L 5433:<internal_host>:5432 <user>@<host>

Remote forward: expose a local port on the serveradvanced

ssh -N -R 8080:localhost:3000 <user>@<host>

SOCKS proxy through the serveradvanced

ssh -N -D 1080 <user>@<host>

Connect through a jump host (bastion)advanced

ssh -J <user>@<bastion> <user>@<host>

Host alias with key and jump hostadvanced

Host prod
  HostName <host>
  User <user>
  IdentityFile ~/.ssh/<ssh_key>
  ProxyJump <bastion>

# then just: ssh prod

Keep the connection aliveadvanced

Host *
  ServerAliveInterval 60
  ServerAliveCountMax 3

Copy a file to a server

scp <file> <user>@<host>:/tmp/

Copy a file from a server

scp <user>@<host>:<remote_path> .

Sync a directory to a server

rsync -avz --progress <path>/ <user>@<host>:<remote_path>/

The trailing slash on the source means “contents of the directory”, not the directory itself.

Mirror a directory, deleting extra files (dry run)advanced

rsync -avz --delete --dry-run <path>/ <user>@<host>:<remote_path>/

rsync over a non-standard SSH portadvanced

rsync -avz -e 'ssh -p <port>' <path>/ <user>@<host>:<remote_path>/