Re: [LARTC] Problems routing mail to particular interface

[George Alexandru Dragoi <waruiinu@gmail.com>]

A good think would be to give a full description to your network
setup, interfaces and so on, maybe there should be stuff like -s
192... -d ! 192../24

On Thu, 22 Jul 2004 12:17:27 -0700, Jens <jens@pacificsun.ca> wrote:
> 192.168.1.2 is the mail server which goes to 192.168.1.1 which is the firewall
> that has the routing script and routs to one of two external interfaces. I
> used PREROUTING based on some how-to's but have never really thought about
> exactly where the marking should take place. It seemed to me that PREROUTING
> was a good choice for marking since the routing rules which depend on the
> marking follow that.
> 
> The flushing is something that got me before but which I am watching like a
> hawk now :)
> 
> Jens
> 
> 
> 
> On Thursday 22 July 2004 02:59, George Alexandru Dragoi wrote:
> > Is the 192.168.1.2 an ip on the router? If yes, you'll have to mark in
> > OUTPUT, not PREROUTING, also, after you set up the rules and routes,
> > did you an
> > ip route flush cache
> > ?
> >
> > I hope these works
> >
> > On Wed, 21 Jul 2004 20:02:32 -0700, Jens <jens@pacificsun.ca> wrote:
> > > I have a particular problem that has caused me grief for some time now
> > > and even though the answer is probably very basic, it has eluded me. I
> > > would appreciate any help or pointers in the right direction.
> > >
> > > I have two links to the internet, one via cable and one via adsl.
> > > Although I would want to add redundancy at a later time, all I want to
> > > get working now is that mail from my server goes out via the adsl link
> > > (it's a fixed IP and I am running into too many cases where my cable
> > > account with it's dynamic IP is blocked by other mail servers).
> > > I have spent considerable time trying to wrap my brain around ip tables,
> > > routing and the such. Although I only see a slight ray of hope in ever
> > > understanding the subject completely, my current problem doesn't (at
> > > first glance) seem to require a degree in rocket science. I have set up
> > > two routing tables (adsl and shaw). I mark packets with "iptables -t
> > > mangle -A PREROUTING -p tcp -- dport 25 -s 192.168.1.2 -j MARK --set-mark
> > > 1" and use "ip rule add fwmark 1 table adsl". To my understanding, the
> > > result of this is that every packet from 192.168.1.2 that comes out of my
> > > mail server via port 25 will get market with '1' and that routing is
> > > decided via table adsl. The adsl table has a default route via the adsl
> > > line. There is also a separate default gateway set up in the regular
> > > routing table to go via the cable connection. I seem to be missing
> > > something because I get the following result .... if I telnet from my
> > > mail server (192.168.1.2) to another mail server via port 25, I get a
> > > timeout. If I telnet to the same server via port 80 I get the connect
> > > message from the other end. To me, this seems to indicate that port 25
> > > messages are marked and are routed differently from the port 80 messages
> > > - just like I would expect. The question is, why the heck am I not
> > > getting anywhere on port 25. The same setup going to the default cable
> > > provider works just fine - this leads me to believe that I don't have
> > > anything in the router/firewall impeding the traffic.
> > > What am I missing ????
> > > Is there any way to trace how my attempts at telnetting thru port 25 are
> > > handled by the router ?
> > > I would be happy to post any further information needed to sort this out.
> > >
> > > Jens
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