October 2007
Intermediate to advanced
1308 pages
161h 13m
English
Content preview from sendmail, 4th EditionBecome an O’Reilly member and get unlimited access to this title plus top books and audiobooks from O’Reilly and nearly 200 top publishers, thousands of courses curated by job role, 150+ live events each month,
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confGBIN...
The set-group-id settings Build macro
The non-set-user-id root version of sendmail (Install sendmail on page 60) uses a set-group-id means of identity instead of the normal set-user-id root means. That is, it assumes the group identity specified, no matter who runs it.
Three macros tune the group identity and permission for this non-set-user-id root version. They are:
confGBINGRPThis macro sets the group that the non-set-user-id root version of sendmail should belong to. The group defaults to
smmsp. If, as illustrated in Add smmsp to /etc/group on page 63, you wish to use a different group, you can do so like this:define(`confGBINGRP', `nullmail') ← use a group name define(`confGBINGRP', `5343') ← use a group number
If you use a positive number that is not too large, it will be accepted no matter what. If you use a name that is not defined in the /etc/group file, you might see the following error and the build will fail:
chgrp: nullmail: unknown group
confGBINMODEThis macro defines the execution mode that the non-set-user-id root version of sendmail will have. The default is mode 2555, which is set-group-id (the 2), and readable and executable by the owner, group, and world (the 555). One reason to change this default might be to prevent ordinary users from copying the binary. You would make such a change like this:
define(`confGBINMODE', `2551') ← correct define(`confGBINMODE', `551') ← wrong, don't omit the leading 2
If you mistakenly omit the leading 2, the created non-
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O’Reilly covers everything we've got, with content to help us build a world-class technology community, upgrade the capabilities and competencies of our teams, and improve overall team performance as well as their engagement.Julian F.
I wanted to learn C and C++, but it didn't click for me until I picked up an O'Reilly book. When I went on the O’Reilly platform, I was astonished to find all the books there, plus live events and sandboxes so you could play around with the technology.Addison B.
I’ve been on the O’Reilly platform for more than eight years. I use a couple of learning platforms, but I'm on O'Reilly more than anybody else. When you're there, you start learning. I'm never disappointed.Amir M.
I'm always learning. So when I got on to O'Reilly, I was like a kid in a candy store. There are playlists. There are answers. There's on-demand training. It's worth its weight in gold, in terms of what it allows me to do.