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Bug 6642

Summary: ypbind failes to bind to NIS Master Server if DNS lookups are not possible
Product: [Retired] Red Hat Linux Reporter: tma
Component: ypbindAssignee: Cristian Gafton <gafton>
Status: CLOSED WORKSFORME QA Contact:
Severity: medium Docs Contact:
Priority: medium    
Version: 6.1CC: tma
Target Milestone: ---   
Target Release: ---   
Hardware: i386   
OS: Linux   
Whiteboard:
Fixed In Version: Doc Type: Bug Fix
Doc Text:
Story Points: ---
Clone Of: Environment:
Last Closed: 2000-01-27 19:15:09 UTC Type: ---
Regression: --- Mount Type: ---
Documentation: --- CRM:
Verified Versions: Category: ---
oVirt Team: --- RHEL 7.3 requirements from Atomic Host:
Cloudforms Team: --- Target Upstream Version:

Description tma 1999-11-02 08:00:13 UTC
Hi folks,

while setting up a NIS Master server on RH6.1 i noticed the
following problem:

OS: RedHat 6.1 (out of the box, no patches installed)
PC: i686,128MB SDRAM,
MB: Abit dual Celeron (currently only 1 CPU)
SCSI: AHA2940U2W
NIC: 3c905B TX

Purpose of this host: It's my internal NIS Master server and
NFS Server for RH 6.1 clients. Later (if everything is
setup) it will become also my primary caching only DNS
server (non authoritative). But for now i did *not* setup
DNS, since i use the external DNS Server of my ISP. I guess
this causes the problem. Please read on.

I connect my internal network via a CISCO ISDN router to the
internet. During installation/setup i always turn of my
CISCO, to prevent insecure broadcasts/packets sent out to
the Internet. I noticed that ypbind is not able to find my
NIS Master server if it can not reach the Internet via my
CISCO (guess it was trying to do a DNS lookup ???). Every
host search path (nsswitch.conf, hosts.conf ...)  specifyes
dns to be the last entry. I use this order "files nis dns"

ypbind is able to bind to my NIS master *only* if access to
the Internet is possble (CISCO must be running).

Does ypbind need a DNS lookup to resolve the NIS master,
even if it's specified in /etc/hosts ???

I will further track down the problem when i have some spare
time, but for now i guess it's because ypbind tries to
resolve some names via DNS.

Please tell me if i'm completely wrong, or if this is
possible (Do i need an internal DNS server???)
If it's possible, it might be a security problem, since
ypbind requests must not be seen on the internet.

Many thanks
Thomas

P.S.: RedHat 6.1 is a wonderfull distribution, keep up the
good work!

Comment 1 Cristian Gafton 2000-01-27 19:15:59 UTC
I thibnk it is the ypserv which is confused about who he really is. tis usually
happens when you alias the hostname of the NIS server to 127.0.0.1 in
/etc/hosts.