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On Friday 15 October 2004 18:06, Kurt Lieber wrote: |
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> On Fri, Oct 15, 2004 at 05:51:15PM +0200 or thereabouts, Christian Parpart |
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wrote: |
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> > I want to backup mx a server that is *not* accessible via default |
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> > port 25. |
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> > Is there a way to configure the backup mx in that way it sends data to |
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> > the master server port != 25? |
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> |
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> It's not entirely clear what exactly you want to do, but you can make mail |
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> respond on any port you want. The problem is going to be that other mail |
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> servers expect to contact you on TCP port 25 and, if you want to receive |
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> mail, you'll need to answer on that port. |
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> |
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> In other words, you can configure a backup mail server to respond on 25, |
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> but you can't get other mail servers (outside of your control) to send mail |
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> to that non-standard port. |
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|
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host mainMX port 1234 (port 25 blocked from outside world) |
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host backupMX port 25 (yet another host in different subnet) |
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|
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important DNS records for domain.tld: |
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IN MX 10 mainMX.domain.tld. |
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IN MX 20 backupMX.domain.tld. |
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|
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all mail going to domain.tld will first go to mainMX.domain.tld, but |
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since its port 25 is blocked for outside world, the source smtp |
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gateway will try the backupMX.domain.tld to deliver post; here we |
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have port 25 listening, so it delivers, now backupMX needs to send |
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this to mainMX (as it's just a backup mx for mainMX) but it's port is |
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(as defined) blocked, even for backupMX. that's why I want backupMX |
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to connect to mainMX to that very known special port 1234. |
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|
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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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|
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Regards, |
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Christian Parpart |
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|
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- -- |
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01:56:54 up 52 days, 13:36, 1 user, load average: 0.15, 0.20, 0.21 |
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