Part 3: AIX Sendmail - Out of the Box

I probably should have started with this - in terms of 1, 2, 3 and more. And, actually, now months later as I start to re-write all this - I did.

Rewrite? Yes, sadly, I opened a document to work on it, thought it was part XYZ that I was writing, and overwrote all the prior pieces. And, a few weeks later - when I wnet back to finish everything up - I saw what I had done. New work gets in the way - so finally, back to this - as I start from scratch on a test server, to slowly work through the steps again - and re-create or create anew - the steps leading to a robust SENDMAIL for AIX.

So - you have installed AIX (5.3 through 7.2) - and what do you have? Read on...

Sendmail on AIX – OOB (Out of the Box)

By default sendmail is configured to be active on port 25 (only) and without any form of encryption. Through AIX 7.1 the fileset containing the base program is bos.net.tcp.client. Starting with AIX 7.2 the base files are in the fileset bos.net.tcp.sendmail. The files for customizing the configuration are in bos.net.tcp.adt.

What does AIX sendmail support after first boot?

The two “simple” commands – to review what sendmail is accepting and supporting are to telnet to port 25 and issue the SMTP command EHLO and from the command line get some debug info.

Accepting

root@x072:[/home/root]telnet localhost 25

Trying...

Connected to loopback.

Escape character is '^]'.

220 x072.home.local ESMTP Sendmail Thu, 1 Aug 2019 20:11:31 GMT

ehlo x.y.z

250-x072.home.local Hello loopback [127.0.0.1], pleased to meet you

250-ENHANCEDSTATUSCODES

250-PIPELINING

250-EXPN

250-VERB

250-8BITMIME

250-SIZE

250-DSN

250-ETRN

250-DELIVERBY

250 HELP

quit

221 2.0.0 x072.home.local closing connection

Connection closed.

Key Features (via debug)

root@x072:[/home/root]sendmail_ssl -d0.1 </dev/null

Discussion

The paragraph accepting shows that a key feature “STARTTLS” is not available. Part 2 shows how to activate STARTTLS. In short, the default sendmail binary does not have the STARTTLS feature. That feature is available in the alternate binary sendmail_ssl

root@x072:[/home/root]sendmail_ssl -d0.1 </dev/null

Version AIX7.1/8.14.4

Compiled with: DNSMAP LDAPMAP LDAP_REFERRALS LOG MAP_REGEX MATCHGECOS

MILTER MIME7TO8 MIME8TO7 NAMED_BIND NDBM NETINET NETINET6

NETUNIX NEWDB NIS NISPLUS PIPELINING SCANF STARTTLS USERDB

USE_LDAP_INIT XDEBUG

Note: in closing - the sendmail version - BASE - is sendmail-8.14.4. The last version released as "easily available" OOS version of sendmail is version 8.15.2