1. Can't construct AIX 4.1 chroot() area where DNS works (for smtpd)
Howdy. I have an AIX 184.108.40.206.01 workstation that I'm trying to set up to be
as hacker-proof as possible, so I'm installing obtuse.com's "smtpd" sendmail
The Makefile includes compile flags for AIX, so obviously there's some way
to get smtpd to work on the platform, but I have been failing because I
can't seem to construct a chroot() tree where DNS works. Every host that
connects to port 25, including localhost, produces an error in the syslog
of the form:
Jun 21 18:07:09 my_machine smtpd: No reverse mapping for address
Error code (5) is the SERVICE_UNAVAILABLE #define from /usr/include/netdb.h,
a kind of catchall error case.
I first tried copying the obvious files (/etc/resolve.conf etc.) into my
chroot() tree, but that didn't help, so I eventually copied in ALL of the
files from /etc (though no files from subdirectories of /etc) and all the
files from /usr/lib (though no files from subdirectories of same). I then
used mknod and chmod to make a mirror image of the /dev directory (though
not /dev/pts/). None of this helped.
You can try this out without smtpd. To take an example from a
comp.unix.solaris thread where the way to fix this same problem on _that_ OS
was discussed, try (as root):
% mkdir -p /your_chroot_dir/usr/bin
% cp -p /usr/bin/finger /your_chroot_dir/usr/bin
finger: Unknown host localhost
This will happen even if you've made a /your_chroot_dir/etc/hosts with
"localhost" in it and an etc/netsvc.conf telling name lookup to look there.
Does anyone know what magic file(s) need(s) to get copied into the chroot()
jail so that DNS will work there? Did I just not go far enough in stopping
before duplicating the subdirectories of /dev, /etc, and /usr/lib?
Naturally, I'd like to construct the minimum-size chroot() tree that'll work.
Dan Harkless | NOTE: Due to SPAM I have implemented a caller-ID-
Unitech Research, Inc. | your Subject to bypass or finger me for more info.
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