Red Hat Bugzilla – Bug 76977
ypserv:: refused connect from x.x.x.x:p to procedure ypproc_match
Last modified: 2015-01-07 19:01:29 EST
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Description of problem:
After upgrading ypserv to ypserv-2.5-2.7x i started getting error messages in
the server like these:
Oct 30 16:00:00 bugs ypserv: refused connect from 192.168.2.20:762 to
The client workstations seem to work the same, and let us login and do ypcat
passwd commands without a hitch.
Version-Release number of selected component (if applicable):
Steps to Reproduce:
1. login to workstation
The workstations are SGI irix machines running Irix 6.5.14.
The /var/yp/securenets of the server was rechecked and is fine., as the
/etc/hosts.allow and /etc/hosts.deny file. I get those errors if i telnet and
login to the workstations. It is not a dns problem, all workstations names are
resolved fine, and the reverse dns is also fine.
I wonder what it's trying to match that doesn't work.
Can you try running "ypserv -d" and attach the output from when a client logs in
We're also seeing these messages here with a set of linux clients. Messages look
Nov 17 21:32:37 xserv1 rpc.mountd: authenticated mount request from
xpc1.ast.cam.ac.uk:1003 for /soft3/home/enrico (/soft3)
Nov 17 21:32:38 xserv1 ypserv: refused connect from 184.108.40.206:33162 to
Nov 17 21:32:53 xserv1 last message repeated 8 times
Nov 17 21:33:32 xserv1 ypserv: refused connect from 220.127.116.11:898 to
They seem to be matching automounter requests. We could try running ypserv -d,
but I assume that might break our cluster, so we have to wait until it is quiet
enough to do so.
For some reason the ports being used are sometimes >1024, and sometimes <1024.
xfr_check_port is set to yes, but I don't know whether that makes any difference.
Another quick comment:
Doing a ypmatch for a map which doesn't exist, e.g. home (rather that
auto.home), reproducably puts this message into the server log:
eg> ypmatch user home
So, maybe some client automounter is configured wrong?
I have now run ypserv in debug mode. This is the output of a telnet attempt to a
client machine and login as root:
ypproc_match(): [From: 192.168.2.67:762]
domainname = "trollhattan"
mapname = "group.bymember"
keydat = "root"
gdbm_open: GDBM Error Code #3
connect from 192.168.2.67
-> Ignored (not a valid map name)
ypproc_all_2_svc(): [From: 192.168.2.67:793]
domain = "trollhattan"
map = "group.byname"
Found: trollhattan/group.byname (1)
connect from 192.168.2.67
Found: trollhattan/group.byname (1)
-> First value returned.
This same telnet results in the following message in the server if the debug
mode for ypserv is off:
Nov 18 15:13:01 bugs ypserv: refused connect from 192.168.2.67:762 to
Regarding the possibility of the culprit being automounter, that was my
suspect for the beginning all along. SGI Irix machines run both autofs and
automounter by default, but before starting this bug thread, i chkconfig'ed them
off and killed the processes. At least in my case that is not it.
I see the exact same problem here, after just having installed RedHat Linux 7.3
with latest updates.
I've been monitoring with tcpdump and found that the message is created by a
Dec 2 17:17:44 ecniks ypserv: refused connect from <src>:867 to procedure
and tcpdump says:
17:17:44.393537 <src>.867 > <dst>.925: udp 104 (DF)
17:17:44.393635 <dst>.925 > <src>.867: udp 32 (DF)
I've checked, and EVERY time a package with '104' ( i guess that's the size? )
arrives, a message is written into the logfile. Don't know if this is helpfull,
but we get a LOT of messages this way ( about 40/50 per minute or so... )
Something is trying to get the map called "group.bymember". We don't set up that
map, and never have, so I wonder why this suddenly appeared.
From some quick googling this looks like some sort of IRIX extension.
My problem is solved!
I found out that all linux clients were calling for the map
services.byservicename, which isn't served by our NIS master service, a Tru64
UNIX system (just the map services.byname instead).
After manipulating this NIS master system to serve the services.byname map as
services.byservicename too, all errors went away!
What worked for firstname.lastname@example.org doesn't work for me. It seems to be an issue
with nis clients requesting maps not available in the server. In the Sgi Irix
case, the map being requested is group.bymember, and this seems to be a Irix'ism
that was ignored before. There are probably two paths to follow now: One, why
does the new ypserv gets bothered with these requests and didn't before? Fix
this. Two, create the group.bymember map, per the following description
"The `group.bymember' map maps user names to a listof groupids which that user
is in. The key is a user name, and the content is that username, a colon, and
then a comma separated list of group ids of groups that the user is in. "
This is best left to someone knowledgeable.
I had the same error message and my solution was like email@example.com's. Our
nis server isn't Linux and doesn't have a shadow map. Somehow
/etc/nsswitch.conf had shadow set to look for files, then nis. This cause the
same error because the map didn't exist.
I thought that I had edited the /etc/nsswitch.conf file properly, but I am
wondering if it got replaced when running "up2date -u" one day.
Concerning `group.bymember' it seems that implementations that use it implement
a fallback such that if the lookup fail they query the other maps and build up
the reverse mapping.
I assume that the warning was added in a later version of ypserv because someone
thought is was useful. (And it clearly is, since some other people here found
out some setup issues due to this.)
So, the best way to solve this would probably be to add group.bymember
generation to the Makefiles. Unfortunately I don't really have the time to do
that at the moment, and neither do I know that code very well.
I would recommend that anyone that need group.bymember functionallity ask about
it upstream. http://www.linux-nis.org/nis/ypserv/index.html is the ypserv
I had the same symptoms after the NIS server upgrade. The messages were the
least of the prolem: the HP-UX clients stopped working. I traced the problem to
the broken functionality of ypserv, see my bug report #85262 against ypserv.
Does anybody from Red Hat read these reports? My report was there for a few
days, and is still brand new.
Red Hat apologizes that these issues have not been resolved yet. We do want to
make sure that no important bugs slip through the cracks.
Red Hat Linux 7.3 and Red Hat Linux 9 are no longer supported by Red Hat, Inc.
They are maintained by the Fedora Legacy project (http://www.fedoralegacy.org/)
for security updates only. If this is a security issue, please reassign to the
'Fedora Legacy' product in bugzilla. Please note that Legacy security update
support for these products will stop on December 31st, 2006.
If this is not a security issue, please check if this issue is still present
in a current Fedora Core release. If so, please change the product and version
to match, and check the box indicating that the requested information has been
If you are currently still running Red Hat Linux 7.3 or 9, please note that
Fedora Legacy security update support for these products will stop on December
31st, 2006. You are strongly advised to upgrade to a current Fedora Core release
or Red Hat Enterprise Linux or comparable. Some information on which option may
be right for you is available at http://www.redhat.com/rhel/migrate/redhatlinux/.
Any bug still open against Red Hat Linux 7.3 or 9 at the end of 2006 will be
closed 'CANTFIX'. Again, if this bug still exists in a current release, or is a
security issue, please change the product as necessary. We thank you for your
help, and apologize again that we haven't handled these issues to this point.
Red Hat Linux is no longer supported by Red Hat, Inc. If you are still
running Red Hat Linux, you are strongly advised to upgrade to a
current Fedora Core release or Red Hat Enterprise Linux or comparable.
Some information on which option may be right for you is available at
Closing as CANTFIX.