I maintain a mailing list for the local web and digital community in Bristol and Bath. This mailing list is coming up to 18 years old and until now has been hosted at my previous company Netsight. It was running on their main mail server, which had evolved into quite a complex setup of Exim, Cyrus Imap, SpamAssassin, Mailman, Squirrelmail, and a number of related tools. All running on FreeBSD.
It came time to move the mailing list off onto it's own to simplify the complex setup and enable parts to be upgraded with less risk. So I thought I'd move it off onto it's own OpenBSD virtual machine, as it is pretty lightweight and running on it's own VM it would stay fairly self contained.
I wanted to try and use as much of the 'built in' components in OpenBSD as possible, namely the MTA (OpenSMTP) and the HTTP server (httpd). The mailing list runs Mailman version 2. There has since been a complete re-write of Mailman, version 3, which is a totally different beast, and based on Django app. As I wanted to keep this pretty minimal and try and move over as much of the setup as I could, I stuck with the legacy mailman 2 setup.
Oh, and just one more thing, as I'm currently doing a lot of experimentation with IPv6 at the moment I thought I'd try and set it up with just IPv6. The VM is running on a server in my office, and my ISP has given me just a single IPv4 address, but an entire /60 IPv6 address space to play with. So by putting it on IPv6 I don't have to worry about NAT to get it accessible from the outside world. As the rest of the world is still mainly IPv4 I set up an SMTP route on my main mail server, hosted with Bytemark to forward mail from IPv4 to the IPv6 mailman server. Similarly with HTTP traffic.
OpenBSD's https server tries to chroot itself to /var/www in order to limit the potential damage an exploit could do. Alas, mailman is quite tricky to get running in a chroot environment. As this whole VM will be exclusively running this mailman server and nothing else, I decided to forego the chroot side of things and get the httpd server to chroot to / which effectively negates the benefits of chroot, but allows us to more easily run mailman.
I installed mailman-2.1.17p0 from OpenBSD's packages collection. Then for /etc/mail/smtpd.conf
# $OpenBSD: smtpd.conf,v 1.7 2014/03/12 18:21:34 tedu Exp $
# This is the smtpd server system-wide configuration file.
# See smtpd.conf(5) for more information.
listen on 2a01:500:6:200:2::2
listen on ::1
table aliases db:/etc/mail/aliases.db
accept from any for domain "under-score.org.uk" alias <aliases> deliver to mbox
accept from local for any relay via smtp://mail.quernus.co.uk
and in /etc/mail/aliases appended the aliases for mailman:
...
# underscore mailing list
underscore: "|/usr/local/lib/mailman/mail/mailman post underscore"
underscore-admin: "|/usr/local/lib/mailman/mail/mailman admin underscore"
underscore-bounces: "|/usr/local/lib/mailman/mail/mailman bounces underscore"
underscore-confirm: "|/usr/local/lib/mailman/mail/mailman confirm underscore"
underscore-join: "|/usr/local/lib/mailman/mail/mailman join underscore"
underscore-leave: "|/usr/local/lib/mailman/mail/mailman leave underscore"
underscore-owner: "|/usr/local/lib/mailman/mail/mailman owner underscore"
underscore-request: "|/usr/local/lib/mailman/mail/mailman request underscore"
underscore-subscribe: "|/usr/local/lib/mailman/mail/mailman subscribe underscore"
underscore-unsubscribe: "|/usr/local/lib/mailman/mail/mailman unsubscribe underscore"
Then set up /etc/httpd.conf to serve up the mailman web UI. This is based on classical CGI scripts. OpenBSD's httpd doesn't support the classical CGI setup, but only the newer 'fastcgi' which is a way of passing requests to a long running process, rather than spawn a process per request.
Luckily OpenBSD also includes slowcgi a gateway from FastCGI to the traditional CGI process. So firstly /etc/httpd.conf
ext_addr="egress"
chroot "/"
logdir "/var/www/logs"
server "default" {
listen on 2a01:500:6:200:2::2 port 80
root "/var/www/htdocs"
# The actual mailman CGI scripts
location "/mailman/*" {
fastcgi socket "/var/www/run/slowcgi.sock"
root { "/usr/local/lib/mailman/cgi-bin/", strip 1 }
}
# The icons referred to by the web interface
location "/icons/*" {
root { "/usr/local/lib/mailman/icons/", strip 1 }
}
# The mailing list archives
location "/pipermail/*" {
root { "/var/spool/mailman/archives/public/", strip 1 }
}
}
Note that I set the chroot parameter to /. This in effect disables the chroot security mechanism. You need to be OK with that. In theory you shouldn't need to do this, as only the slowcgi process needs to be able to see the actual mailman CGI scripts, but due to the way the path to the scripts is calculated, you have to disable the chroot in httpd too. The first location block above is the one that points to the main CGI scripts for mailman. It passes the location via the unix domain socket specified.
The slowcgi process doesn't need any setup, just starting. So my /etc/rc.conf.local file looks like:
ntpd_flags="-s"
smtpd_flags=""
slowcgi_flags="-p /"
httpd_flags=""
pkg_scripts="mailman"
Passing the -p / flag to slowcgi disables the chroot as well, so that it is able to find the mailman scripts to run.
So there we have a pretty minimal setup, just enough to accept mail via SMTP, process it in mailman and send mail out to smarthost relay, also access to the archives and web management interface via HTTP.
In total there are about 40 processes running:
load averages: 0.15, 0.17, 0.14 linda.quernus.co.uk 21:34:22
43 processes: 42 idle, 1 on processor
CPU states: 0.0% user, 0.0% nice, 0.2% system, 0.0% interrupt, 99.8% idle
Memory: Real: 173M/445M act/tot Free: 540M Cache: 187M Swap: 0K/480M
PID USERNAME PRI NICE SIZE RES STATE WAIT TIME CPU COMMAND
14917 _mailman 2 0 23M 32M sleep select 0:43 0.00% python2.7
25162 _mailman 2 0 21M 30M sleep select 0:42 0.00% python2.7
25278 _mailman 2 0 17M 25M sleep select 0:40 0.00% python2.7
14513 _mailman 2 0 20M 30M sleep select 0:40 0.00% python2.7
5857 _mailman 2 0 16M 24M sleep select 0:39 0.00% python2.7
26636 _mailman 2 0 8704K 15M sleep select 0:38 0.00% python2.7
7008 _mailman 2 0 8440K 15M sleep select 0:38 0.00% python2.7
13568 _pflogd 4 0 684K 404K sleep bpf 0:20 0.00% pflogd
19428 _smtpq 2 0 1900K 2876K idle kqread 0:02 0.00% smtpd
3726 _smtpd 2 0 2868K 5004K idle kqread 0:01 0.00% smtpd
11513 root 2 0 792K 1136K sleep poll 0:01 0.00% cron
1 root 10 0 536K 552K sleep wait 0:01 0.00% init
12359 matt 2 0 3680K 3028K idle select 0:01 0.00% sshd
32041 _smtpd 2 0 1608K 2520K idle kqread 0:00 0.00% smtpd
428 _smtpd 2 0 1756K 2644K idle kqread 0:00 0.00% smtpd
2484 www 2 0 1212K 2316K sleep kqread 0:00 0.00% httpd
8653 _mailman 2 0 16M 24M idle select 0:00 0.00% python2.7
19052 root 3 0 652K 760K idle ttyin 0:00 0.00% ksh
2330 www 2 0 1156K 2180K sleep kqread 0:00 0.00% httpd
1102 _smtpd 2 0 1668K 2476K idle kqread 0:00 0.00% smtpd
19445 _syslogd 2 0 1124K 1504K idle kqread 0:00 0.00% syslogd
16320 matt 2 0 3692K 3056K sleep select 0:00 0.00% sshd
28230 _ntp 2 -20 1084K 2896K idle poll 0:00 0.00% ntpd
26805 root 3 0 664K 772K idle ttyin 0:00 0.00% ksh
1199 www 2 0 1140K 2180K idle kqread 0:00 0.00% httpd
23519 www 2 0 996K 1884K idle kqread 0:00 0.00% httpd
19390 www 2 0 696K 1288K idle kqread 0:00 0.00% slowcgi
28522 root 18 0 656K 752K sleep pause 0:00 0.00% ksh
2809 root 2 0 3800K 3556K idle poll 0:00 0.00% sshd
30896 root 2 0 3792K 3564K idle poll 0:00 0.00% sshd
7317 root 2 0 1544K 2300K idle kqread 0:00 0.00% smtpd
14527 _smtpd 2 0 1396K 2104K idle kqread 0:00 0.00% smtpd
12559 _mailman 10 0 8484K 5232K idle wait 0:00 0.00% python2.7
9705 root 2 0 1036K 1436K idle select 0:00 0.00% sshd
3165 matt 18 0 632K 732K idle pause 0:00 0.00% ksh
6618 matt 18 0 628K 728K idle pause 0:00 0.00% ksh
18860 root 2 0 1124K 1336K idle netio 0:00 0.00% syslogd
5870 root 2 0 1136K 2164K idle kqread 0:00 0.00% httpd
17986 root 2 -20 668K 1528K idle poll 0:00 0.00% ntpd
23120 root 2 0 620K 600K idle netio 0:00 0.00% pflogd
17361 root -6 0 236K 200K sleep piperd 0:00 0.00% cat
17714 root 28 0 592K 1760K onproc - 0:00 0.00% top
11321 _ntp 2 0 944K 1260K idle poll 0:00 0.00% ntpd
The VM has 1G of memory, but looks like it could probabaly get away with 512MB just fine.
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