I'm using gdm to manage displays for about 50 thin clients, and have been doing so for quite a while. Yesterday morning a *lot* (but not all) of the thin clients did not have login screens, and looking at my logs I'm finding the following for the clients that are not working. Sep 24 07:23:28 brinn gdm[984]: gdm_xdmcp_decode: Received opcode REQUEST from client 192.168.164.143 Sep 24 07:23:28 brinn gdm[984]: gdm_xdmcp_handle_request: Got REQUEST from 192.168.164.143 Sep 24 07:23:28 brinn gdm[984]: gdm_xdmcp_handle_request: pending=17, MaxPending=18, sessions=-2144, MaxSessions=100 Sep 24 07:23:28 brinn gdm[984]: gdm_xdmcp_display_dispose_check (opussm:0) Sep 24 07:23:28 brinn gdm[984]: gdm_display_dispose: Disposing opussm:0 Sep 24 07:23:28 brinn gdm[984]: gdm_auth_secure_display: Setting up access for opussm:0 Sep 24 07:23:28 brinn gdm[984]: gdm_auth_secure_display: Setting up network access Sep 24 07:23:28 brinn gdm[984]: gdm_auth_secure_display: Setting up access for opussm:0 - 1 entries Sep 24 07:23:29 brinn gdm[984]: gdm_xdmcp_display_alloc: display=opussm:0, session id=1032871746, pending=17 Sep 24 07:23:29 brinn gdm[984]: gdm_xdmcp_send_accept: Sending ACCEPT to 192.168.164.143 with SessionID=1032871746 Sep 24 07:23:32 brinn gdm[984]: gdm_xdmcp_decode: Received opcode MANAGE from client 192.168.164.143 Sep 24 07:23:32 brinn gdm[984]: gdm_xdmcp_handle_manage: Got MANAGE from 192.168.164.143 Sep 24 07:23:32 brinn gdm[984]: gdm_xdmcp_handle_manage: Got Display=0, SessionID=1032871740 from 192.168.164.143 Sep 24 07:23:32 brinn gdm[984]: gdm_xdmcp_handle_manage: Failed to look up session id 1032871740 Sep 24 07:23:32 brinn gdm[984]: gdm_xdmcp_send_refuse: Sending REFUSE to 1032871740 Sep 24 07:23:32 brinn gdm[984]: gdm_forward_query_lookup: Host 192.168.164.143 not found Sep 24 07:23:32 brinn gdm[984]: gdm_xdmcp_decode: Received opcode MANAGE from client 192.168.164.143 Sep 24 07:23:32 brinn gdm[984]: gdm_xdmcp_handle_manage: Got MANAGE from 192.168.164.143 Sep 24 07:23:32 brinn gdm[984]: gdm_xdmcp_handle_manage: Got Display=0, SessionID=1032871740 from 192.168.164.143 Sep 24 07:23:32 brinn gdm[984]: gdm_xdmcp_handle_manage: Failed to look up session id 1032871740 Sep 24 07:23:32 brinn gdm[984]: gdm_xdmcp_send_refuse: Sending REFUSE to 1032871740 Sep 24 07:23:32 brinn gdm[984]: gdm_forward_query_lookup: Host 192.168.164.143 not found On the thin client side I'm seeing Sep 24 07:17:04 Xserver: Enabling MIT-MAGIC-COOKIE-1 authorization Sep 24 07:17:04 Xserver: xdmcp: sending MANAGE packet to 192.168.164.34 Sep 24 07:17:06 Xserver: xdmcp: receive ACCEPT packet from host 192.168.164.34 Sep 24 07:17:06 Xserver: xdmcp: sending MANAGE packet to 192.168.164.34 Sep 24 07:17:08 Xserver: xdmcp: receive REFUSE packet from host 192.168.164.34 Sep 24 07:17:08 Xserver: xdmcp: sending START_CONNECTION packet to 192.168.164.34 Sep 24 07:17:10 Xserver: xdmcp: sending START_CONNECTION packet to 192.168.164.34 Sep 24 07:17:11 Xserver: xdmcp: receive REFUSE packet from host 192.168.164.34 Sep 24 07:17:13 Xserver: xdmcp: receive ACCEPT packet from host 192.168.164.34 I see Chad Walstrom posted this exact problem to a debian list a couple of years ago, but it doesn't appear that anyone replied. I've made some changes to the file system recently, but none of them 'feel' relevant to this problem. Obviously I could be wrong, but in the interest of brevity (too late for that probably) I won't detail them in this post. Any help? Thanks, Kent