#ssh

17 one-liners with this tag.

Allow a port only from a specific IP with ufw

#ufw allow from 198.51.100.0/24 to any port 22 proto tcp

cautionFirewall

Connect to an internal server through a jump host

$ssh -J admin@bastion.example.com webuser@10.0.0.12

Copy a directory to another server with tar over SSH

$tar czf - -C /var/www/vhosts/example.com/httpdocs . | ssh webuser@neuserver.example.com "tar xzf - -C /var/www/vhosts/example.com/httpdocs"

Debug SSH connection problems with verbose output

$ssh -vvv -p 22 webuser@server.example.com

Enable ufw without locking yourself out

#ufw allow 22/tcp && ufw enable

destructiveFirewall

Expose a local service on a server with a reverse SSH tunnel

$ssh -N -R 8080:127.0.0.1:3000 webuser@server.example.com

IP addresses with the most failed SSH logins

#journalctl -u ssh --since "24 hours ago" --no-pager | grep -oE 'Failed password for .* from [0-9a-f.:]+' | awk '{print $NF}' | sort | uniq -c | sort -rn | head -20

harmlessSecurity

List all SSH keys authorized on the server

#find / -xdev -path '*/.ssh/authorized_keys' -type f -exec awk 'NF && !/^#/ {print FILENAME ": " $NF}' {} + 2>/dev/null

harmlessSecurity

Make a remote port available locally with an SSH tunnel

$ssh -N -L 3307:127.0.0.1:3306 webuser@server.example.com

Resume an interrupted transfer of large files

$rsync -avP /var/backups/example.com-2026-10-09.tar.gz webuser@backup.example.com:/home/webuser/backup/

cautionrsync and backup

Reuse SSH connections with ControlMaster

$ssh -o ControlMaster=auto -o ControlPath=~/.ssh/cm-%C -o ControlPersist=10m webuser@server.example.com

Run a command on multiple servers one after another

$for h in web1.example.com web2.example.com web3.example.com; do echo "== $h"; ssh -o BatchMode=yes -o ConnectTimeout=5 "$h" 'uptime; df -h /'; done

Run a local script on a remote server

$ssh webuser@server.example.com 'bash -s' < ./check.sh

Run rsync with limited bandwidth

$rsync -avz --bwlimit=5000 /var/www/vhosts/example.com/httpdocs/ webuser@backup.example.com:/home/webuser/backup/httpdocs/

cautionrsync and backup

Set up a SOCKS proxy over an SSH connection

$ssh -N -D 1080 webuser@server.example.com

Stream a tar backup directly to another server over SSH

$tar -czf - -C /var/www/vhosts/example.com/httpdocs . | ssh webuser@backup.example.com 'cat > /home/webuser/backup/example.com-httpdocs.tar.gz'

cautionrsync and backup

Transfer files to another server with rsync over SSH

$rsync -avz -e 'ssh -p 22' /var/www/vhosts/example.com/httpdocs/ webuser@backup.example.com:/home/webuser/backup/httpdocs/

cautionrsync and backup