# SSH

## Generate public key from private
```bash
ssh-keygen -f id_rsa -y > id_rsa.pub
```

## Port forwarding
```bash
# forward : 172.16.0.1:80 -> 172.16.0.2 -> 127.0.0.1:4080
ssh -f -N -L 4080:172.16.0.1:80 172.16.0.2
```

## Allow old algorithm
```bash
ssh -oKexAlgorithms=+diffie-hellman-group1-sha1 -oHostKeyAlgorithms=+ssh-dss 172.16.0.1
```

# Options

ServerAliveInterval