Created Chaining Warpgates together (markdown)

Chaining-Warpgates-together.md

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+Sometimes exposing a host on the network to the outside is not an option. In this case you can opt to forward connections from one Warpgate to another.
+
+Note: this is transparent to the client (except for two "warpgate connected" messages in interactive sessions) - there are no SSH "jump hosts" involved in this setup.
+
+# Copy outer Warpgate's public key
+
+* Run `warpgate client-keys` and copy the Ed25519 public key:
+
+```
+➜  ~ warpgate client-keys
+16:55:10  INFO Using config: "/etc/warpgate.yaml" (users: 1, targets: 6, roles: 1)
+Warpgate SSH client keys:
+(add these to your target's authorized_hosts file)
+
+ssh-ed25519 AAAAC3NzaC1lZDI1NTE5AAxxxx+3RBsT5  # <-- this line
+rsa-sha2-256 AAAADHJzYS1zaGEyLTI1Ngxxxx
+```
+
+# Set up inner Warpgate
+
+* Add your targets as usual
+* Add a "jump user" (here we'll be using `wg-jump` as a username) and add the outer Warpgate's public key as a credential:
+
+```diff
+  users:
++   - username: wg-jump
++     roles: ['warpgate:admin']  # Note that we're adding the user to the admin group for simplicity here
++     credentials:
++       - type: publickey
++         key: ssh-ed25519 AAAAC3NzaC1lZDI1NTE5AAxxxx+3RBsT5
+
+```
+
+* Add the targets on the inner network as well:
+
+```diff
+  targets:
+    - name: Web admin
+      allow_roles:
+        - "warpgate:admin"
+      web_admin: {}
++   - name: server-behind-jump
++     allow_roles:
++     - warpgate:admin
++     ssh:
++       host: 192.168.77.2
+```
+
+* Check your config with `warpgate check`.
+* Check connection to the target with `warpgate test-target server-behind-jump`
+
+# Set up outer Warpgate
+
+* Add the targets on the inner network again, using the inner Warpgate's address and port, as well as the Warpgate-style username:
+
+```
+  targets
++   - name: internal-server
++     allow_roles: ['warpgate:admin']
++     ssh:
++       host: 192.168.77.1
++       port: 2222
++       username: 'wg-jump:server-behind-jump'
+```
+
+* Check your config with `warpgate check`.
+* Check connection to the target _through the inner Warpgate_ with `warpgate test-target internal-server`
+
+# Connect
+
+You can now grab the connection command from the landing page (or the admin UI) as usual and test it on a client:
+
+```
+ssh <username>:internal-server@<outer-warpgate> -p <outer-wg-port>
+```
+
+Note that the names user in the internal Warpgate's config file are not exposed to users.