Added instructions for binding to multiple addresses

docs/firststeps-bind_to_multiple_addresses.md

@@ -0,0 +1,69 @@
+By default mailcow listens on all addresses, this can be problematic if you have multiple IPs on the host and you are running services already on same ports mailcow uses.
+
+This example will show how to bind services to 1 IPv4 address and 1 IPv6 address. Though this could be expanded to as many addresses as you want.
+
+A `docker-compose.override.yml` file will be used instead of editing the `docker-compose.yml` file directly. This is to maintain updatability, as the `docker-compose.yml` file gets update regularly and your changes will be overwritten.
+
+For this example the host will have the following addresses
+`fd:0:0:0:0:0:0:1`
+`fd:0:0:0:0:0:0:2`
+`192.168.1.1`
+`192.168.1.2`
+
+##Changing Bindings In mailcow.conf
+Say we wanted to bind all the services to `192.168.1.2` and `fd:0:0:0:0:0:0:2`. To do this we need to bind the following to a specific IP address in the `mailcow.conf`
+
+    HTTP_PORT=80
+    HTTP_BIND=192.168.1.2
+
+    HTTPS_PORT=443
+    HTTPS_BIND=192.168.1.2
+
+    SMTP_PORT=192.168.1.2:25
+    SMTPS_PORT=192.168.1.2:465
+    SUBMISSION_PORT=192.168.1.2:587
+    IMAP_PORT=192.168.1.2:143
+    IMAPS_PORT=192.168.1.2:993
+    POP_PORT=192.168.1.2:110
+    POPS_PORT=192.168.1.2:995
+    SIEVE_PORT=192.168.1.2:4190
+    DOVEADM_PORT=192.168.1.2:19991
+
+
+##Overriding docker-compose.yml
+Then we need to create `docker-compose.override.yml` with the following. This extends the configuration already defined in `docker-compose.yml`
+
+    version: '2.1'
+    services:
+
+        dovecot-mailcow:
+          ports:
+            - 'fd:0:0:0:0:0:0:2:143:143'
+            - 'fd:0:0:0:0:0:0:2:993:993'
+            - 'fd:0:0:0:0:0:0:2:110:110'
+            - 'fd:0:0:0:0:0:0:2:995:995'
+            - 'fd:0:0:0:0:0:0:2:4190:4190'
+
+        postfix-mailcow:
+          ports:
+            - 'fd:0:0:0:0:0:0:2:25:25'
+            - 'fd:0:0:0:0:0:0:2:465:465'
+            - 'fd:0:0:0:0:0:0:2:587:587'
+
+       nginx-mailcow:
+          ports:
+           - 'fd:0:0:0:0:0:0:2:80:80'
+           - 'fd:0:0:0:0:0:0:2:443:443'
+
+
+
+## Restart Mailcow#
+
+!!! warning
+    mailcow will fail to start or not start completely if you mess up the address bindings
+
+To restart mailcow run the following
+```
+docker-compose stop
+docker-compose up -d
+```

mkdocs.yml

@@ -38,6 +38,7 @@ nav:
   - 'Logging': 'firststeps-logging.md'
   - 'Local MTA on Docker host': 'firststeps-local_mta.md'
   - 'Sync Jobs Migration': 'firststeps-sync_jobs_migration.md'
+  - 'Bind To Multiple Addresses': 'firststeps-bind_to_multiple_addresses.md'
 - 'Models':
   - 'Sender and receiver model': 'model-sender_rcv.md'
   - 'ACL': 'model-acl.md'