Date: Sun, 11 Apr 1999 14:23:49 +0100 From: Brian Somers <brian@Awfulhak.org> To: Rahul Dhesi <dhesi@rahul.net> Cc: freebsd-current@FreeBSD.ORG Subject: Re: showing full host names in output from who/finger/last Message-ID: <199904111323.OAA57685@keep.lan.Awfulhak.org> In-Reply-To: Your message of "Sat, 10 Apr 1999 17:18:08 PDT." <199904110018.AA21927@bolero-x.rahul.net>
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> For some years I have been using patched utilities under SunOS to show
> full host names in the output from the 'who', 'finger', and 'last'
> commands. (Traditional UNIXes truncate host names to about 16
> characters.)
>
> I have been thinking of patching FreeBSD programs to do the same, but
> since I have been updating my source tree often, it will be a bit
> painful to maintain my changes through the updates. So I will do it
> only if the FreeBSD developers would be willing to incorporate my
> changes into the official FreeBSD source tree. Below is what I would
> do -- tell me if it could be make a part of FreeBSD.
>
> - Update all programs that write to utmp and wtmp to check the host name
> length, and if it's too long, insert the IP address instead
I've been doing this in current in the last few days. There's now a
new function in libutil called realhostname(). You pass it a maximum
fields size (UT_HOSTSIZE?). If it can fit the gethostbyaddr() result
into the field, AND that name resolves back to the same IP number,
the full host name is used, otherwise the IP number is used.
The trimdomain() function has also been fixed and documented.
I believe all the stuff in libexec now works and I've just committed
some ssh patches that'll do the same for sshd.
> - Update all of the above programs, if they accept a host name on the
> command line, to also accept an additional argument that specifies
> the IP address.
> - Update all programs that invoke the above programs and supply a
> host name to also supply the IP address.
I think the host name that's passed should be considered correct.
However, if it doesn't fit in the ut_host field, a gethostbyname() is
required. Passing an IP number would therefore probably be a quite
good addition if it avoids that call.
> - Update all programs that look up wtmp and utmp such that, if they find
> an IP address, they do a double-reverse DNS resolution (IP address ->
> fqdn -> IP address) and, if successful and consistent, display the
> host name instead of the IP address. The user may if he wishes supply
> a command-line argument to suppress the reverse resolution and cause
> the IP address to be displayed directly.
I'd agree with Matt here - don't make the default suddenly require
lookups, but I'd say that if a lookup is being done, it should be a
correct double lookup (realhostname() from libutil).
> For example, rlogind might invoke /usr/bin/login as:
>
> /usr/bin/login -h 98.portland-23-24rs.or.dial-access.att.net -i 12.73.137.98
>
> /usr/bin/login notices that the host name is too long, inserts
> 12.73.137.98 into utmp and wtmp. If no -i argument is available,
> /usr/bin/login would do a forward DNS resolution of the host name to get
> the IP address.
Yep. This sounds pretty rational.
> Below are samples from the 'last' and 'finger' commands with only the
> really long host names included and some information x'd out to protect
> user privacy. (Obviously comumnar alignment doesn't work as well for
> very long host names, but only a small fraction are that long. The rest
> will display normally in aligned columns.)
>
> == output from 'finger ==
> Login Name Idle When Where
> xxxxxx xxxxxxxxxxxxxx 7 Apr 9 13:14 kaibab.redbacknetworks.com
> xxx xxxxxxxxxxxxxxx Apr 10 16:37 dyn164.rahul.net
> xxxxxxxx xxxxxxxxxxxx 8 Apr 10 16:48 c166.ppp.tsoft.com
> xxxxx xxxxxxxxxxx Apr 9 23:35 \
> cxxxxxxx-x.xxxxx.occa.home.com
> xxxxx xxxxxxxxxxxx * 10 Apr 10 16:44 01-025.006.popsite.net
>
> == output from 'last' ==
> xxx s1 98.portland-23-24rs.or.dial-access.att.net Sat Apr 10 16:50 - 16:50 (00:00)
> xxxxxx rd oak-hiper1b-145-145.dialup.slip.net Sat Apr 10 16:48 - 16:51 (00:03)
> xxxx p6 netcom14.netcom.com Sat Apr 10 15:36 - 15:39 (00:03)
> xxxxx s2 adsl-xxx-xxx-xxx-10.dsl.snfc21.pacbell.net Sat Apr 10 13:51 - 13:52 (00:00)
> xxxxxxxx sb tnt9-xxx-xxx-17-189.dialup.HiWAAY.net Sat Apr 10 12:54 - 14:54 (02:00)
> xxxxxx s2 oak-hiper1a-15-79.dialup.slip.net Sat Apr 10 12:37 - 12:40 (00:02)
> xxxx r2 dnai-207-181-255-82.dialup.dnai.com Sat Apr 10 11:41 - 13:58 (02:17)
> xxxxxxx q8 sdn-ar-001casfraP195.dialsprint.net Sat Apr 10 08:28 - 13:30 (05:01)
> == END ==
This is fine for ``w'' as I believe it already does the lookup. But
in the ``who'' and ``last'' cases, they should display the contents
of ut_host by default unless some consistent option is used - it's a
pity that this is the opposite of the -n option to route/netstat and
probably others :-(
I'll review & commit your changes when you've got them done if you
haven't already got someone.
--
Brian <brian@Awfulhak.org> <brian@FreeBSD.org>
<http://www.Awfulhak.org>; <brian@OpenBSD.org>
Don't _EVER_ lose your sense of humour ! <brian@uk.FreeBSD.org>
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