[PerSteinar.Iversen@adm.hioslo.no] libc/1331: gethostbyaddr vs. RFC 2317

[Andreas Jaeger <aj at suse dot de>]

We've received the appended bug report about gethostbyaddr and
classless IN-ADDR.ARPA delegation as specified by RFC 2317.

Here's the output of 
> host 158.36.154.34
34.154.36.158.IN-ADDR.ARPA is a nickname for 34.32.154.36.158.IN-ADDR.ARPA
> nslookup  158.36.154.34
Server:  arthur.rhein-neckar.de
Address:  192.168.27.1

Name:    server.h-radet.hioslo.no
Address:  158.36.154.34
Aliases:  34.154.36.158.in-addr.arpa

Could a network expert tell me what we should do?  Should we filter
out the in-addr.arpa?

Andreas

---

• Subject: libc/1331: gethostbyaddr vs. RFC 2317
• From: PerSteinar dot Iversen at adm dot hioslo dot no
• Date: Mon Sep 27 20:12:25 1999

Topics:
   libc/1331: gethostbyaddr vs. RFC 2317


----------------------------------------------------------------------

Date: Mon, 27 Sep 1999 07:06:33 -0400
From: PerSteinar.Iversen@adm.hioslo.no
To: bugs@gnu.org
Subject: libc/1331: gethostbyaddr vs. RFC 2317
Message-Id: <199909271106.HAA12421@delysid.gnu.org>


>Number:         1331
>Category:       libc
>Synopsis:       gethostbyaddr vs. RFC 2317
>Confidential:   no
>Severity:       non-critical
>Priority:       medium
>Responsible:    libc-gnats
>State:          open
>Class:          change-request
>Submitter-Id:   unknown
>Arrival-Date:   Mon Sep 27 07:10:02 EDT 1999
>Last-Modified:
>Originator:     PerSteinar.Iversen@adm.hioslo.no
>Organization:
net
>Release:        2.1.1
>Environment:
RedHat linux
>Description:
An increasing number of PTR records are allocated as defined by
RFC 2317. gethostbyaddr does not look up CNAME records, this
means that programs that believes that translating
IP-numbers to a name and back again is a nice thing to do, fails.

For example sendmail adds "may be forged" in the received headers
for addresses that uses classless IN-ADDR.ARPA delegation.

>How-To-Repeat:
For example the host(1) utility from bind 8.2.1:

# host 158.36.154.34
34.154.36.158.IN-ADDR.ARPA is a nickname for 34.32.154.36.158.IN-ADDR.ARPA%0
>Fix:
>Audit-Trail:
>Unformatted:



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-- 
 Andreas Jaeger   aj@suse.de	aj@arthur.rhein-neckar.de
  for pgp-key finger ajaeger@aixd1.rhrk.uni-kl.de