I should add to this that I'm able to run X-windows programs on my local workstation, such as gnome-terminal, xclock, etc. Xming opens them up with no issues whatsoever. It's just that I can't get a gdm login screen when trying to connect via xdmcp.
If it's any help here is what I see in the /var/log/messages file with debug turned on. IP address and hostname have been changed to protect the innocent:
Oct 1 20:24:22 server gdm[14790]: gdm_xdmcp_decode: Received opcode QUERY from client 10.10.10.10 Oct 1 20:24:22 server gdm[14790]: gdm_xdmcp_handle_query: Opcode 2 from 10.10.10.10 Oct 1 20:24:22 server gdm[14790]: gdm_xdmcp_send_willing: Sending WILLING to 10.10.10.10 Oct 1 20:24:23 server gdm[14790]: gdm_xdmcp_decode: Received opcode REQUEST from client 10.10.10.10 Oct 1 20:24:23 server gdm[14790]: gdm_xdmcp_handle_request: Got REQUEST from 10.10.10.10 Oct 1 20:24:23 server gdm[14790]: gdm_xdmcp_handle_request: xdmcp_pending=0, MaxPending=4, xdmcp_sessions=0, MaxSessions=16, ManufacturerID= Oct 1 20:24:23 server gdm[14790]: gdm_xdmcp_display_dispose_check (cpe-10-10-10-10.austin.res.rr.com:0) Oct 1 20:24:23 server gdm[14790]: gdm_auth_secure_display: Setting up access for cpe-10-10-10-10.austin.res.rr.com:0 Oct 1 20:24:23 server gdm[14790]: gdm_auth_secure_display: Setting up access Oct 1 20:24:23 server gdm[14790]: gdm_auth_secure_display: Setting up access for cpe-10-10-10-10.austin.res.rr.com:0 - 1 entries Oct 1 20:24:23 server gdm[14790]: gdm_xdmcp_display_alloc: display=cpe-10-10-10-10.austin.res.rr.com:0, session id=-246206558, xdmcp_pending=1 Oct 1 20:24:23 server gdm[14790]: gdm_xdmcp_send_accept: Sending ACCEPT to 10.10.10.10 with SessionID=-246206558 Oct 1 20:24:23 server gdm[14790]: gdm_xdmcp_decode: Received opcode MANAGE from client 10.10.10.10 Oct 1 20:24:23 server gdm[14790]: gdm_xdmcp_handle_manage: Got MANAGE from 10.10.10.10 Oct 1 20:24:23 server gdm[14790]: gdm_xdmcp_handle_manage: Got Display=0, SessionID=-246206558 Class=MIT-unspecified from 10.10.10.10 Oct 1 20:24:23 server gdm[14790]: gdm_xdmcp_handle_manage: Looked up cpe-10-10-10-10.austin.res.rr.com:0 Oct 1 20:24:23 server gdm[14790]: gdm_choose_indirect_lookup: Host 10.10.10.10 not found Oct 1 20:24:23 server gdm[14790]: gdm_forward_query_lookup: Host 10.10.10.10 not found Oct 1 20:24:23 server gdm[14790]: gdm_display_manage: Managing cpe-10-10-10-10.austin.res.rr.com:0 Oct 1 20:24:23 server gdm[14790]: loop check: last_start 0, last_loop 0, now: 1222907063, retry_count: 0 Oct 1 20:24:23 server gdm[14790]: Resetting counts for loop of death detection Oct 1 20:24:23 server gdm[14790]: gdm_display_manage: Forked slave: 14864 Oct 1 20:24:23 server gdm[14864]: gdm_slave_start: Starting slave process for cpe-10-10-10-10.austin.res.rr.com:0 Oct 1 20:24:23 server gdm[14864]: gdm_slave_start: Loop Thingie Oct 1 20:24:23 server gdm[14864]: gdm_slave_run: Opening display cpe-10-10-10-10.austin.res.rr.com:0