Thursday, September 14, 2000
The new technical editor at DaveWorld (you just wouldn't get it)
A mailing list I'm on has its own website which is a collaborative journal.
Because of life, the current technical editor of the site (he who actually puts the entries up) had to take a leave of absence from the position and I volunteered to take over.
First thing first, reorganize the site. There currently is no organization, or rather, it's a flat structure where all the pages are in the top level directory. Not a good thing long term.
Then there's the matter of the HTML …
Expanding on EXPN
Once again Spring is having problems with mailing her journal entries, only this time it's with Yahoo.
What is it? EXPN is all the rage now? Must expand email
addresses?
Sigh.
So I decide to fix it once and for all. I check the configuration file for
Sendmail and don't
see any obvious way to disable the EXPN command. Not wanting to
hack the source code to remove the EXPN command I figure the next
easiest way is to hack the actual binary and change any occurence of
E-S-P-N-NULBYTE such that sendmail will no longer be able to actually
respond to the EXPN command. I have some software I wrote
years ago that makes this relatively easy to do.
So, I find the occurences of E-X-P-N-NULBYTE and make the changes.
No go. Sendmail still reponds to the EXPN command.
Okay, so next it's occurrences of e-x-p-n-NULLBYTE and that's when I find
the curious string “noexpn” in the executable. Hmmmmmmmm … I
think to myself. Might there actually be a way to disable the
EXPN command?
So I search
the site for noexpn and I
find
this:
- PrivacyOptions=opt,opt,…
Set the privacy options. “Privacy” is really a misnomer; many of these are just a way of insisting on stricter adherence to the SMTP protocol. The options can be selected from:
- public
- Allow open access
- needmailhelo
- Insist on HELO or EHLO command before MAIL
- needexpnhelo
- Insist on HELO or EHLO command before EXPN
- noexpn
- Disallow EXPN entirely
- needvrfyhelo
- Insist on HELO or EHLO command before VRFY
- novrfy
- Disallow VRFY entirely
- restrictmailq
- Restrict mailq command
- restrictqrun
- Restrict -q command line flag
- noreceipts
- Don't return success DSNs
- goaway
- Disallow essentially all SMTP status queries
- authwarnings
- Put X-Authentication-Warning: headers in messages
The
goawaypseudo-flag sets all flags exceptrestrictmailqandrestrictqrun. If mailq is restricted, only people in the same group as the queue directory can print the queue. If queue runs are restricted, only root and the owner of the queue directory can run the queue. Authentication Warnings add warnings about various conditions that may indicate attempts to spoof the mail system, such as using an non-standard queue directory.
I don't know if it's A Good Thing or A Bad Thing that you can learn more about a program from scanning the executable than you could probably get reading the documentation.
![[The future's so bright, I gotta wear shades]](https://www.conman.org/people/spc/about/2023/1023.t.jpg "The future's so bright, I gotta wear shades")