docs: using scaleway vpc bastion ssh (#1436)

Co-authored-by: Vincent Germain <[email protected]>
Co-authored-by: Jules Castéran <[email protected]>
Co-authored-by: Rowena Jones <[email protected]>
Co-authored-by: Rémy Léone <[email protected]>

Author: 5 people

docs/guides/using-vpc-bastion-ssh.md

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+---
+page_title: "Using Scaleway SSH Bastion"
+description: |-
+  Using Scaleway SSH Bastion config.
+---
+
+# How to use Scaleway VPC SSH Bastion config
+
+In this guide you'll learn how to deploy Scaleway SSH bastion to your Scaleway Private Network using the Scaleway Terraform provider.
+After Bastion is deployed, you can connect (SSH) to virtual machines in the virtual network via Bastion using the private IP address of the VM.
+When you connect to a VM, it doesn't need a public IP address, client software, agent, or a special configuration.
+
+## Prerequisites
+
+*	You have created a virtual machine (Instance) in a VPC Private Network. Check our example below.
+
+1. When you deploy Bastion, the values are pulled from the Private Network in which your VM resides.
+   1. This VM doesn't become a part of the Bastion deployment itself, but you do connect to it later in the exercise.
+
+2. If you don't have any VMs connected to the Private Network, use the `scaleway_instance_private_nic` or the attribute `private_network` on `scaleway_instance_server` to connect.
+
+3. Detach any VMs that are attached to a `scaleway_instance_ip`.
+
+  **Note**: Your VMs and Private Network should be in the same Availability Zone. e.g. `fr-par-1`
+
+```hcl
+provider "scaleway" {
+	zone = "fr-par-1"
+}
+```
+
+```hcl
+variable "machine_count" {
+  description = "Number of virtual machines in private network"
+  default = 3
+}
+
+# SCALEWAY VPC PRIVATE NETWORK
+resource scaleway_vpc_private_network "pn" {
+  name = "myprivatenetwork"
+  zone = "fr-par-1"
+}
+
+# SCALEWAY VPC VIRTUAL MACHINES
+resource scaleway_instance_server "servers" {
+  count	= var.machine_count
+  name 	= "machine${count.index}"
+  image = "ubuntu_focal"
+  type  = "DEV1-S"
+}
+
+# SCALEWAY INSTANCES PRIVATE NETWORK CONNECTION
+resource scaleway_instance_private_nic "nic" {
+  count              = length(scaleway_instance_server.servers)
+  private_network_id = scaleway_vpc_private_network.pn.id
+  server_id          = scaleway_instance_server.servers[count.index].id
+}
+```
+
+## Reserve a public gateway IP
+
+Reserve your public IP, allowing it to reach the public Internet, as well as to forward (masquerade) traffic from member Instances of attached Private Networks.
+
+This IP is a static IPv4 address designed for dynamic cloud computing.
+
+```hcl
+# SCALEWAY PUBLIC GATEWAY IP
+resource scaleway_vpc_public_gateway_ip "pgw_ip" {
+}
+```
+
+## Set up your Public Gateway
+
+Public Gateways sit at the border of Private Networks and allow you to enable the bastion.
+You can also choose your port of preference on `bastion_port` option. The default port is `61000`
+
+You can check the types of gateways currently supported via our CLI.
+
+```shell
+scw vpc-gw gateway-type list
+```
+
+Example:
+
+```hcl
+resource scaleway_vpc_public_gateway "pgw" {
+  type = "VPC-GW-S"
+  bastion_enabled = true
+  ip_id = scaleway_vpc_public_gateway_ip.pgw_ip.id
+}
+```
+
+## Configure your DHCP on your subnet
+
+The [DHCP](https://fr.wikipedia.org/wiki/Dynamic_Host_Configuration_Protocol) server sets the IPv4 address dynamically,
+which is required to communicate over the private network.
+
+The `dns_local_name` is the [TLD](https://en.wikipedia.org/wiki/Top-level_domain), the value by default is `priv`.
+This is used to resolve your Instance on a Private Network.
+
+In order to resolve the Instances using your Bastion you should set the `dns_local_name` with `scaleway_vpc_private_network.pn.name`.
+
+Please check our API [documentation](https://developers.scaleway.com/en/products/vpc-gw/api/v1/#dns-local-name-5b691b) for more details.
+
+```hcl
+resource scaleway_vpc_public_gateway_dhcp "dhcp" {
+  subnet = "192.168.1.0/24"
+  dns_local_name = scaleway_vpc_private_network.pn.name
+}
+```
+
+## Attach your VPC Gateway Network to a Private Network
+
+To enable DHCP on this Private Network you must set `enable_dhcp` and `dhcp_id`.
+Do not set the `address` attribute.
+
+```hcl
+resource scaleway_vpc_gateway_network "gn" {
+  gateway_id          = scaleway_vpc_public_gateway.pgw.id
+  private_network_id  = scaleway_vpc_private_network.pn.id
+  dhcp_id             = scaleway_vpc_public_gateway_dhcp.dhcp.id
+  enable_dhcp         = true
+}
+```
+
+## Config my Bastion config
+
+You should add your config on your local config file e.g: `~/.ssh/config`
+
+```
+Host *.myprivatenetwork
+ProxyJump bastion@<your-public-ip>:<bastion_port>
+```
+
+Then try to connect to it:
+
+```shell
+ssh root@<vm-name>.myprivatenetwork
+```
+
+For further information using our console please check [our dedicated documentation](https://www.scaleway.com/en/docs/network/vpc/how-to/use-ssh-bastion/).