GDM uses ipv6 even when no ipv6 interfaces on system

[vandyswa]

Binary package hint: gdm

Bring up a fully updated Lucid Lynx Ubuntu system, with ipv6 disabled by sysctl.conf. Verify no IPv6 on interfaces with ifconfig. Look at listen list--gdm is listening on an IPv6 (wildcard) port! Log in, check your $DISPLAY. You have an IPv6 address.

Symptoms... long delays, apparently due to timeouts on IPv6 code paths. Also, apps and window managers which don't do IPv6 will not work (WMaker, for instance, apparently).

I recommend that GDM should either check interfaces and only enable address families actually present on a given system. Or at least give us a -4 switch to force its behavior.

[vandyswa (ajv-cauriumbin)]

Note this all refers to XDMCP. Sorry for not stating that explicitly.

[Adam Dorsey (adorsey)]

Having the same issue on Ubuntu Maverick. Xvnc cannot connect to GDM via XDMCP on localhost because of this issue. Exact same config worked fine in Lucid.

Oct 19 10:14:32 leftovers xinetd[1385]: START: Xvnc pid=1930 from=xxx.xxx.xxx.xxx
Oct 19 10:14:32 leftovers gdm-binary[925]: DEBUG(+): GdmXdmcpDisplayFactory: decode_packet: GIOCondition 1
Oct 19 10:14:32 leftovers gdm-binary[925]: DEBUG(+): Address family:2 (inet) hostname:(null) host:(null) port:(null) local:1 loopback:1
Oct 19 10:14:32 leftovers gdm-binary[925]: DEBUG(+): Address family:2 (inet) hostname:(null) host:(null) port:(null) local:0 loopback:0
Oct 19 10:14:32 leftovers gdm-binary[925]: DEBUG(+): GdmAddress: looking up hostname: leftovers
Oct 19 10:14:32 leftovers gdm-binary[925]: DEBUG(+): family=10 sock_type=1 protocol=6 flags=0x2 canonname=leftovers#012
Oct 19 10:14:32 leftovers gdm-binary[925]: DEBUG(+): family=10 sock_type=2 protocol=17 flags=0x2 canonname=(null)#012
Oct 19 10:14:32 leftovers gdm-binary[925]: DEBUG(+): family=10 sock_type=3 protocol=0 flags=0x2 canonname=(null)#012
Oct 19 10:14:32 leftovers gdm-binary[925]: DEBUG(+): family=2 sock_type=1 protocol=6 flags=0x2 canonname=(null)#012
Oct 19 10:14:32 leftovers gdm-binary[925]: DEBUG(+): family=2 sock_type=2 protocol=17 flags=0x2 canonname=(null)#012
Oct 19 10:14:32 leftovers gdm-binary[925]: DEBUG(+): family=2 sock_type=3 protocol=0 flags=0x2 canonname=(null)#012
Oct 19 10:14:32 leftovers gdm-binary[925]: DEBUG(+): family=2 sock_type=1 protocol=6 flags=0x2 canonname=(null)#012
Oct 19 10:14:32 leftovers gdm-binary[925]: DEBUG(+): family=2 sock_type=2 protocol=17 flags=0x2 canonname=(null)#012
Oct 19 10:14:32 leftovers gdm-binary[925]: DEBUG(+): family=2 sock_type=3 protocol=0 flags=0x2 canonname=(null)#012
Oct 19 10:14:32 leftovers gdm-binary[925]: DEBUG(+): Address family:10 (inet6) hostname:(null) host:(null) port:(null) local:0 loopback:0
Oct 19 10:14:32 leftovers gdm-binary[925]: DEBUG(+): GdmXdmcpDisplayFactory: Received opcode QUERY from client ::ffff:ff7f:0:0%1905946208 : 43524
Oct 19 10:14:32 leftovers gdm-binary[925]: DEBUG(+): GdmXdmcpDisplayFactory: Sending WILLING to ::ffff:ff7f:0:0%1905946208
Oct 19 10:14:34 leftovers gdm-binary[925]: DEBUG(+): GdmXdmcpDisplayFactory: decode_packet: GIOCondition 1
Oct 19 10:14:34 leftovers gdm-binary[925]: DEBUG(+): Address family:10 (inet6) hostname:(null) host:(null) port:(null) local:0 loopback:0
Oct 19 10:14:34 leftovers gdm-binary[925]: DEBUG(+): GdmXdmcpDisplayFactory: Received opcode QUERY from client ::ffff:ff7f:0:0%1905946208 : 43524
Oct 19 10:14:34 leftovers gdm-binary[925]: DEBUG(+): GdmXdmcpDisplayFactory: Sending WILLING to ::ffff:ff7f:0:0%1905946208
Oct 19 10:14:38 leftovers gdm-binary[925]: DEBUG(+): GdmXdmcpDisplayFactory: decode_packet: GIOCondition 1
Oct 19 10:14:38 leftovers gdm-binary[925]: DEBUG(+): Address family:2 (inet) hostname:(null) host:(null) port:(null) local:1 loopback:1
Oct 19 10:14:38 leftovers gdm-binary[925]: DEBUG(+): Address family:2 (inet) hostname:(null) host:(null) port:(null) local:0 loopback:0
Oct 19 10:14:38 leftovers gdm-binary[925]: DEBUG(+): GdmAddress: looking up hostname: leftovers
Oct 19 10:14:38 leftovers gdm-binary...