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