From: Paul Alukal (
Date: Thu Oct 14 1993 - 02:44:01 CDT

Here is my original mail:

>Hi Sun Managers,
>We have a problem with DNS/NIS at our site. I could not locate a
>similar situation in any summary (of sun managers group) related to
>Machine: Sparcserver 4/690
>SunOS 4.1.3
>Our DNS table on the sun server looks up to When we do a
>telnet to, from any of the NIS machines we get a
>segmentation fault (core dump). If I do a telnet to the IP number
>(e.g., it works. However, we can telnet to any other
>site, both by domain names or IP addresses (DNS works fine).
>The response I got from Merit Network regarding the above problem is
>that there could be a bug in the NIS DNS support. There are 11 machines
>servicing and thus the name lookup returns 11 A
>records. If the NIS DNS code has some kind of statically compiled
>limit for the number of records, this could be breaking it.
>How can I fix the above problem? Will this go away with any patch or
>some other way of NIS setup? Again, I am not sure whether this
>situation is discussed in any DNS summaries in this group, I was unable
>to find it.
>Thank you in advance for any help or suggestions.
>Paul Alukal
>Paul Alukal
>GMI Engineering & Management email:
>Institute, Computer Center
>1700 West Third Avenue Telephone: (313) 762-7964
>Flint, MI 48504 Facsimile: (313) 762-9744

It looks like I need to install a patch (even though some replies points
to different patch numbers for this problem). Thanks to the following
people for their reply. All replies are enclosed.

Peter Smith <peter@sucia.Stanford.EDU>
david@srv.PacBell.COM (David St. Pierre) (Glenn Satchell - Uniq Professional Services)
Barry Margolin <barmar@Think.COM>

From: Peter Smith <peter@sucia.Stanford.EDU>


  I think there is a bug that causes ftp and ping to dump core when
connecting to a host with multiple DNS A records. I realize that you
asked about telnet, but this sounds like the same problem. There is a
libc jumbo patch that fixes this problem, and some others, but guess
what, it is only for 4.1.2. I think the same problem is in 4.1.3 but
apparently there is no patch for that. If you find a version for 4.1.3,
please let me know.

The bug report number is 1054748 and the jumbo patch is 100532-04.

I think this problem only happens on NIS machines.
From: david@srv.PacBell.COM (David St. Pierre)

bugid 1054748, patch 100890-02 (or greater). aka the libc patch.
From: (Glenn Satchell - Uniq Professional Services)

Hi Paul,

There is a patch for a couple of problems with ypserv and DNS
operations, here's part of the README. I hope it helps.

You may also like to think about installing a newer version of named.
Sun ships named 4.8.1 - version 4.8.3 is available which fixes a couple
of bugs in the earlier version. It is publicly available, I suggest
that you use archie to find a site near to you. Note that you can
install the new named and still run with DNS via NIS setup.

Patch-ID# 100482-04
Keywords: security ypserv ypxfrd maps DNS res_send resolv.conf nameserver
Synopsis: SunOS 4.1;4.1.1;4.1.2;4.1.3: ypserv and ypxfrd fix, plus DNS fix
Date: 16/Nov/92
SunOS release: 4.1, 4.1.1, 4.1.2, 4.1.3
Unbundled Product:
Unbundled Release:
Topic: ypserv and ypxfrd security patch, plus DNS patch
BugId's fixed with this patch: 1036869 1039839 1082319 1082320 1080353 1076977
Changes incorporated in this version: 1076977
  Note: This patch includes 1076977 bugfix from patch 100465, and as
         such, this patch obsoletes 100465.
Architectures for which this patch is available: sun3(all), sun4(all)
Obsoleted by:
Problem Description:
        Bug 1036869
        Security - ypserv will send maps to anyone who can guess the
        Bug 1039839
        DNS used in conjunction with NIS may generate syslog messages
        to the console something like :
        nres_gethostbyaddr: != its.correct.IP.addr
        Bug 1082319
        Security - ypserv will send maps to anyone via the portmapper.
        Bug 1082320
        Security - ypxfrd will send maps to anyone.
        Ypxfrd does not check whether the person transferring the map
        is root on his machine, when the map is ``secure''. As a
        consequence, any user can get the password map if the
        NIS master is running ypxfrd.
        Bug 1080353
        The problem is whenever the primary name server downloads an
        'A' record to the secondary system and this 'A' record contains
        more then 36 IP addresses. It will cause ypserv on the
        secondary system to dump core.
        Bug 1078977
        DNS lookup will fail if the first nameserver in /etc/resolv.conf
        is up but has no nameserver daemon running. The ECONNREFUSED will
        be carried on down to the other nameservers listed in resolv.conf
        even if they are up and their nameserver daemons are running.
This patch contains the following fixes:
        1. ypserv - for bug 1036869, 1039839 and 1080353.
        2. ypxfrd - for bug 1082320.
        3. portmap - for bug 1082319.
In order to prevent these NIS security problems, all of the
above fixes need to work together.
Both the "ypserv" and "ypxfrd" patch use a /var/yp/securenets
file and, if present, only responds to IP addresses in the
range given. This file is only read when the daemons (both
ypserv & ypxfrd) start. To get a change in /var/yp/securenets
to take effect, one must kill and restart the daemons.
The format of the file is one of more lines of:
        netmask netaddr
        In the 2nd example, the netmask is
        and the network address is 128.311.10.0 . This
        setup will only allow the ypserv to respond to
        those IP addresses which are within the subnet
        128.311.10 range.


Glenn Satchell            | "This is a unix system.
Uniq Professional Services Pty Ltd  ACN 056 279 335  | I can do this easy."
PO Box 70, Paddington, NSW 2021, (Sydney) Australia  |
Phone 02 360 7434 Pager 016 287 000 Fax 02 331 2572  | - Lex, Jurassic Park
       "Sun Accredited System Consultants"           |
From: Barry Margolin <barmar@Think.COM>

This is bug 1054748; the limit is apparently 10. It's supposedly fixed in the libc patches 100890 (domestic version) and 100891 (international version). "Fixed" probably just means that they increased the limit, though. -- Barry Margolin System Manager, Thinking Machines Corp. {uunet,harvard}!think!barmar --------------------------------------------------------------------------- From: Subject: Re: DNS/NIS Problem


Sorry not to have the solution, but we've found the same problem yesterday evening, and I found your post in sun-managers. A professor that used to work at umich ran into it first.

Have you had any luck in solving the problem? If you have or have started on a solution we would surely appreciate any information you have found.

Many thanks, -johnj ---------------------------------------------------------------------------

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