ssh-to-remote-hosts-through-a-proxy-or-bastion-host

# What is bastiot host?

Bastion host is usually public-facing, hardened systems that serve as an entrypoint to systems behind a firewall or other restricted location, and they are especially popular with the rise of cloud computing

# Proxy Jump

## Command
```
$ ssh -J <bastion_host> <remote-host>
```

## Hard-coding proxy hosts in ~/.ssh/config

```
# In the ~/.ssh/config

### The bastion host
Host bastion-host-farm-test
  Hostname 10.10.10.10
  
Host remote-host-web-farm-test
  Hostname 192.168.0.2
  ProxyJump bastion-host-farm-test
```

# Forwarding stdin and stdout

`ProxyCommand` works by forwarding standard in (stdin) and standard out (stdout) from the remote machine thought the proxy or bastion hosts.

## Command

```
$ ssh -o ProxyCommand="ssh -W %h:%p bastion-host" remote-host
```

## Hard-coding proxy hosts in ~/.ssh/config

```
Host bastion-host
  Hostname 10.10.10.10
  
Host remote-host
  ProxyCommand ssh bastion-host -W %h:%p
  Hostname 192.168.0.2
```

# Agent forwarding 

## Command

```
ssh -A -t <ip_terminal> "ssh -A -t 10.10.55.51"
```