1 |
> I could maybe achieve this using iptables on backupMX that |
2 |
> detects tcp:backupMX:25 to connect to tcp:mainMX:25 and redirects this traffic |
3 |
> to tcp:mainMX:1234. |
4 |
|
5 |
Using IPTables would probably be overkill -- especially since postfix |
6 |
handles this quite nicely. Take at a look at /etc/postfix/transport -- |
7 |
it should help (or 'man transport')... |
8 |
|
9 |
Basically, what you'd want to do is have an entry in backupMX's |
10 |
/etc/postfix/transport that would say something like: |
11 |
|
12 |
* smtp:[mainMX]:1234 |
13 |
|
14 |
...which would forward all mail coming into backupMX on port 25 to |
15 |
mainMX on port 1234, using SMTP. The [] around mainMX suppresses MX |
16 |
lookups, so you won't get stuck in a mail loop. |
17 |
|
18 |
You'd also need to setup mainMX to listen on port 1234. To do so, edit |
19 |
/etc/postfix/master.cf, and duplicate the "smtp" line, like so: |
20 |
|
21 |
... |
22 |
# ========================================================================== |
23 |
# service type private unpriv chroot wakeup maxproc command + args |
24 |
# (yes) (yes) (yes) (never) (50) |
25 |
# ========================================================================== |
26 |
smtp inet n - n - - smtpd |
27 |
1234 inet n - n - - smtpd |
28 |
... |
29 |
|
30 |
|
31 |
Restart postfix on mainMX and backupMX and you should be good to go. |