Local port forwarding

  • Access something they can access but I can't access
  • Bypass port block

From gate:

ssh -L [gate port]:[target ip]:[target port] [user]@[gate ip]

Example: access slashdot:80 through localhost:8080

ssh -L localhost:8080:dest.lan:80 gateway.lan
  • Bind `localhost:8080`
  • to `dest.lan:80` (from the POV of the gateway)
  • through `gateway.lan`

To run in background -N -f

Check that AllowTcpForwarding is set to yes on remote SSH server

Dynamic port forwarding

Used as a web proxy (socks).

From gate:

ssh -D [gate port] [user]@[target ip]

Remote port forwarding

  • Give someone else a port on my machine through SSH

From target:

 ssh -R [gate port]:localhost:[target port] [user]@[gate port]

If you have access to a remote SSH server, you can set up a remote port forwarding as follows:

ssh -R 8080:dest.lan:3000 -N -f gateway.lan
  • Bind `gateway:8080`
  • to `dest.lan:3000` (from my POV)

Make sure GatewayPorts is set to yes in the remote SSH server.

SFTP chroot

Match User user
	ForceCommand sftp-server.exe
	ChrootDirectory "E:\"
	AuthorizedKeysFile "E:\.ssh\authorized_keys"

Use existing agent

# find ssh sockets
ssh_sock="$(find /tmp/ssh*/agent* -print -quit)" 

if [ -n "$ssh_sock" ] && [ -f "$HOME/.agent" ]; then
	# an agent is running and we saved the config
	. "$HOME/.agent"  
	# agent is not running or we didn't save config
	eval "$(ssh-agent | tee "$HOME/.agent")"  
	ssh-add "$HOME/.ssh/id_ed25519"  

# cleanup
unset ssh_sock

Kill frozen session


  • Enter
  • ~ (tilde)
  • . (period)

Install pubkeys from GitHub

mkdir -p "$HOME/.ssh"
chmod 0700 "$HOME/.ssh"
curl >> "$HOME/.ssh/authorized_keys"
sort -u "$HOME/.ssh/authorized_keys" > "$HOME/.ssh/authorized_keys.bak"
mv "$HOME/.ssh/authorized_keys.bak" "$HOME/.ssh/authorized_keys"
chmod 0700 "$HOME/.ssh/authorized_keys"

Encrypt/decrypt with SSH keys

  • Convert the public key into pem format
ssh-keygen -f path/to/ -e -m pem > ~/
  • Using the public pem file to encrypt a string
cat ~/some_file.txt |
	openssl rsautl -encrypt -pubin -inkey ~/ > ~/encrypted.txt
  • To decrypt, you'll need the private key
cat ~/encrypted.txt |
	openssl rsautl -decrypt -inkey path/to/id_rsa > ~/decrypted.txt