xdmcp and dns

[Tom Callahan]

You could re-enable DHCP, and just set PEERDNS=no in the ifcfg-eth*
files so that it won't change when DHCP is done.

Thanks,

Tom Callahan
TESSCO Technologies
(443)-506-6216
callahant at tessco.com

A real engineer only resorts to documentation when the keyboard dents on the forehead get too noticeable.



Andrew Bell Test wrote:

>Hello list,
>
>I'm running RHEL 3 with xdmcp enabled for remote X11 using gdm. We have
>cygwin running on windows PC's connecting to the Linux machine. 
>
>My problem is that cygwin was failing to connect to the Linux box when
>the second Linux NIC (NIC1) was up. 
>
>After trawling the logs I found the initial part of the handshaking for
>a failed gdm connect went like this:
>
>Dec 16 10:55:03 compileserver gdm[2916]: gdm_xdmcp_decode: Received
>opcode QUERY from client 192.168.0.5
>Dec 16 10:55:03 compileserver gdm[2916]: gdm_xdmcp_send_willing: Sending
>WILLING to 192.168.0.5
>Dec 16 10:55:04 compileserver gdm[2916]: gdm_xdmcp_decode: Received
>opcode REQUEST from client 192.168.0.5
>Dec 16 10:55:14 compileserver gdm[2916]: gdm_auth_secure_display:
>Setting up access for 192.168.0.5:0 - 1 entries
>...
>
>Where as a successful connect with Nic1 lo went like this:
>
>Dec 16 10:55:03 compileserver gdm[2916]: gdm_xdmcp_decode: Received
>opcode QUERY from client 192.168.0.5
>Dec 16 10:55:03 compileserver gdm[2916]: gdm_xdmcp_send_willing: Sending
>WILLING to 192.168.0.5
>Dec 16 10:55:04 compileserver gdm[2916]: gdm_xdmcp_decode: Received
>opcode REQUEST from client 192.168.0.5
>Dec 16 10:55:14 compileserver gdm[2916]: gdm_auth_secure_display:
>Setting up access w2kantonyja.devnet.com:0 - 1 entries
>...
>
>Ahh I thought, so gdm_auth_secure_display is failing to resolve
>192.168.0.5 to w2kantonyja.devnet.com. NIC1 was using DHCP and peerdns
>was set to true. After inspecting the resolv.conf I found the nameserver
>was being issued erroneously therefore no gethostbyname. Great. I have
>no control over the router issuing the dns server via a client dhcp
>request, so I've temporarily assigned Nic1 a static IP and turned off
>peerdns, then manually adjusted /etc/resolv.conf to point at the
>nameserver running locally. Now I can do a host 192.168.0.5 which
>correctly returns w2kantonyja.devnet.com. I thought this would suffice,
>but no, still can't use cygwin with Nic1 up. So in shear desperation
>I've added the host names to /etc/hosts and it all works perfectly.
>
>My question is what's wrong with my reverse dns lookup if host
>xxx.xxx.xxx.xxx returns a hostname locally, why does gdm still fail to
>correctly resolve IP -> Hostname for the gdm auth ?
>
>TIA
>
>Andrew. 
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