Jails, loopback interfaces and sendmail

[Dirk Engling]

Dear fellow hackers,

since jail can be bound on multiple IP addresses I tend to clone
multiple loopback interfaces and add one loopback address to each jail

cloned_interfaces="lo1 lo2 lo3"
ifconfig_lo1_alias0="inet 127.0.0.2 netmask 0xffffffff"
ifconfig_lo2_alias0="inet 127.0.0.3 netmask 0xffffffff"
ifconfig_lo3_alias0="inet 127.0.0.4 netmask 0xffffffff"
..

no this is not yet optimal, since I can not run several jails on a
single external IP anymore, but at least local daemons are not visible
to the outside world, anymore.

However, grep -R 127.0.0.1 /etc reveals, that sendmail in many places
assumes localhost to be on 127.0.0.1 instead of looking it up in
/etc/hosts or using 127.0.0.0/8 to identify a local connection.

I worry that more programmers made those assumptions, possibly breaking
more tools.

My question is: Who's the right guy to beg to fix sendmail or
alternatively would it be smart to allow each jail to have its own
concept of 127.0.0.1 on a dummy interface mapped to all jails, that
itself doesn't count as a bound IP address (thus allowing the jail to
bind to an already bound ip address) and is not routed between jails?

Any ideas?

  erdgeist