01-24-2008
Serious un-pingable stumper of a problem...
I have been busting my head over a network issue at work recently. I believe the problem to be in the L2 domain, but "the powers that be" believe that it looks more like a server port related problem. And the biggest problem of all is that EVERYBODY in the Engineering Department uses this file-server...
The symptoms are as follows:
- A samba connection is shared out from "FileServ_1" to my desktop. While having a file open for read/write, I will lose the file (aka. the persistence of connection), and will be prompted by my App to save a local copy (lucky me).
- From that point, I immediately (being prepared) switch to a shell in which I kick off a ping to "FileServ_1"... then another shell I bypass DNS & go straight for the IP... then another shell I have a remote connection from a totally different subnet, also pinging "FileServ_1"... and finally a trace-route running from both my desktop and the remote connection.
- From ALL pings I receive timeouts & from all traces I find the last hop is the dead-zone.
Although "the powers that be" make a strong case for their point, I have noticed "network topology changes" being reported at the switch (indicating a loop?) and I have been able to serial-console "FileServ_1" and watch it while it is supposedly "down"... only problem is: It never thinks that it is down.
- Eth1 (till last week was the only port plugged in) never reports any issues (at least not at any default log levels) and from what I can see there is no way to tell if the ICMP packets are dying on the way in or on the way out.
Finally, as if things were not bad enough, they decided last week to make Eth0 a redundant fail-over for Eth1... which amazingly seemed to lighten the problem from "a few minutes of un-ping" to "a few seconds of un-ping"... and now, instead of happening 10 times a day it happens only once or twice.
So first things first (unless you have better ideas), I am wondering how to turn up the logging of ICMP (thats kernel level right?) and possibly Eth* logging so that I don't have to resort to sniffing for the entire day till it happens. Cause if nothing else, I would like to diagnose this problem correctly and get something done about it.
Any Help?
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LEARN ABOUT DEBIAN
ypbind
ypbind(8) System Manager's Manual ypbind(8)
NAME
ypbind - NIS binding process
SYNOPSIS
ypbind [ -c ] [ -d|-debug ] [ -broadcast ] [ -broken-server ] [ -ypset ] [ -ypsetme ] [ -no-ping ] [ -f configfile ] [ -local-only ] [
-ping-interval ping-interval ] [ -no-dbus ]
ypbind --version
DESCRIPTION
ypbind finds the server for NIS domains and maintains the NIS binding information. The client (normally the NIS routines in the standard C
library) could get the information over RPC from ypbind or read the binding files. The binding files resides in the directory /var/yp/bind-
ing and are conventionally named [domainname].[version]. The supported versions are 1 and 2. There could be several such files since it
is possible for an NIS client to be bound to more than one domain.
After a binding has been established, ypbind will send YPPROC_DOMAIN requests to the current NIS server at 20 seconds intervals. If it
doesn't get an response or the NIS server reports that he doesn't have this domain any longer, ypbind will search for a new NIS server. All
15 minutes ypbind will check to see if the current NIS server is the fastest. If it find a server which answers faster, it will switch to
this server. You could tell ypbind to use network broadcasts to find a new server, what is insecure, or you could give it a list of known
secure servers. In this case ypbind will send a ping to all servers and binds to first one which answers.
Unless the option -debug is used, ypbind detaches itself from the controlling terminal and puts itself into background. ypbind uses sys-
log(3) for logging errors and warnings. At startup or when receiving signal SIGHUP, ypbind parses the file /etc/yp.conf and tries to use
the entries for its initial binding.
A broadcast entry in the configuration file will overwrite a ypserver/server entry and a ypserver/server entry broadcast. If all given
server are down, ypbind will not switch to use broadcast. ypbind will try at first /etc/hosts and then DNS for resolving the hosts names
from /etc/yp.conf. If ypbind couldn't reconfigure the search order, it will use only DNS. If DNS isn't available, you could only use IP-
addresses in /etc/hosts. ypbind could only reconfigure the search order with glibc 2.x. If the -broadcast option is specified, ypbind
will ignore the configuration file. If the file does not exist or if there are no valid entries, ypbind exit.
This ypbind version listens for DBUS messages from NetworkManager. If no NetworkManager is running at startup, ypbind will behave as usual
and assumes there is a working network connection. If NetworkManager is running on the system, ypbind will only search and provide NIS
informations, if NetworkManager tells that a network connection is available. If NetworkManager establishes a connection, ypbind will
reread all configuration files, registers at the local portmapper and try to search NIS servers. If NetworkManager drops a connection,
ypbind will unregister from portmapper.
OPTIONS
-broadcast
Send a broadcast to request the information needed to bind to a specific NIS server. With this option, /etc/yp.conf will be ignored.
-ypset Allow root from any remote machine to change the binding for a domain via the ypset(8) command. By default, no one can change the
binding. This option is really insecure. If you change a binding for a domain, all the current known servers for this domain will be
forgotten. If the new server goes down, ypbind will use the old searchlist.
-ypsetme
The same as -ypset, but only root on the local machine is allowed to change the binding. Such requests are only allowed from loop-
back.
-c ypbind only checks if the config file has syntax errors and exits.
-debug starts ypbind in debug mode. ypbind will not put itself into background, and error messages and debug output are written to stan-
dard error.
-broken-server
lets ypbind accept answers from servers running on an illegal port number. This should usually be avoided, but is required by some
ypserv(8) versions.
-no-ping
ypbind will not check if the binding is alive. This option is for use with dialup connections to prevent ypbind from keeping the
connection unnecessarily open or causing autodials.
-f configfile
ypbind will use configfile and not /etc/yp.conf
-local-only
ypbind will only bind to the loopback device and is not reachable from a remote network.
-ping-interval ping-interval
The default value for ypbind to check, if a NIS server is still reachable, is 20 seconds. With this options another frequency in
seconds can be specified.
-no-dbus
Disables DBUS support if compiled int.
--version
Prints the version number
FILES
/etc/yp.conf
configuration file.
/var/yp/binding/[domainname].[version]
binding file containing information about each NIS domain.
/var/run/ypbind.pid
contains the process id of the currently running ypbind master process.
SEE ALSO
syslog(3), domainname(1), yp.conf(5), ypdomainname(8), ypwhich(1), ypserv(8), ypset(8)
AUTHOR
ypbind-mt was written by Thorsten Kukuk <kukuk@suse.de>.
ypbind-mt Version 1.20.1 August 2006 ypbind(8)