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Jason Antman
Asked: 2011-12-01 06:54:11 +0800 CST

How can I tell which clients are connecting to a NIS/ypserv master server?

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I don't have much experience working with NIS at all, as I came from an LDAP environment. I have a project to move a bunch of clients within a NIS domain to point at a new NIS master server. There's no config management in place, and no real authoritative list of every machine in the domain.

How do I verify that no NIS clients are talking to the old master? I don't see any ypserv log files (the old master is a RedHat AS 3 box...), and AFAIK there's no reliable way to tcpdump for NIS traffic since it uses RPC.

Any ideas?

nis yp

1 Answers

  1. Best Answer

    Funnily enough, I was doing that just this morning, to verify that people were talking to my new NIS server.

    Firstly, find the port that ypserv is on with

    oldserver> rpcinfo -p|grep ypserv
    100004    2   udp    844  ypserv
    100004    1   udp    844  ypserv
    100004    2   tcp    847  ypserv
    100004    1   tcp    847  ypserv

    Then, you can use tcpdump to look for traffic:

    oldserver> sudo tcpdump -n -n port 847 or port 844
[...]
15:09:18.714526 IP 192.168.20.102.707 > 192.168.1.87.844: UDP, length 56
15:09:18.714679 IP 192.168.1.87.844 > 192.168.20.102.707: UDP, length 28
15:09:20.717203 IP 192.168.1.105.900 > 192.168.1.87.844: UDP, length 56
15:09:20.717296 IP 192.168.1.87.844 > 192.168.1.105.900: UDP, length 28
15:09:21.326160 IP 192.168.1.39.719 > 192.168.1.87.844: UDP, length 56
15:09:21.326225 IP 192.168.1.87.844 > 192.168.1.39.719: UDP, length 28

    As you can see, my server (192.168.1.87) is definitely getting traffic. If you don't see anything after a half-hour or so, you're not getting anything.

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