SMTP Bind Address/Virtual Interfaces

["Neal Morgan" <Neal@morgan-systems.com>]

Greetings all:

I have experimented some with the suggested scheduler.conf changes to
specify a bind address for outbound smtp connections.  I find it doesn't
work as expected when:

1) the IP is assigned to a virtual interface
2) there are other virtual interfaces on that physical interface in the
same network
3) the IP either has no default gateway assigned in the main table (per
"ip route show table main"), or has a default gateway but it is not the
first listed for this network as reported in the main table

Iptables (output/mangle) logging shows zmailer's first outbound packet
specifying the wrong IP address (first IP of default route for the
desired interface).  For example:

Scheduler.conf has this:

smtp/*.com
	maxchannel=199
	maxring=8
	command="smtp -s -L [1.2.3.8] -l ${LOGDIR}/smtpout"


ip route show table main reports:
default via 1.2.3.1 dev eth4  src 1.2.3.2
default via 1.2.3.1 dev eth4  src 1.2.3.8
...

Scheduler/SMTP will always use 1.2.3.2 as the bind address even though
1.2.3.8 was requested.

I can supply additional details, but in short it seems zmailer finds the
first match on the network address and accepts the src address attached
to it - whether this address is my requested one or not, all scheduler
smtp connections matching my "-L" use it.  Further, it doesn't seem to
renegotiate that choice again until after the scheduler has been
restarted - e.g. a change to the routes doesn't get noticed until the
next zmailer restart.

Seems the issue is somewhere in zgetbindaddr or zgetifaddress but I'm a
little too tired and slow to figure it out now.  Any suggestions on the
best fix/method to troubleshoot would be appreciated.

As a side note, smtpserver is perfectly happy binding to my virtual
interfaces...



Thanks,

Neal Morgan




-
To unsubscribe from this list: send the line "unsubscribe zmailer" in
the body of a message to majordomo@nic.funet.fi