x11/gdm: default IPv6 disables IPv4 for xdmcp

[Eugene M. Kim]

Try setting ipv6_ipv4mapping="YES" in /etc/rc.conf and rebooting.

For security reasons, *BSD intentionally breaks RFC 3493 by disabling 
IPv4-mapped addresses by default (net.inet6.ip6.v6only=1).  (For 
example, if one were to block incoming connections from an IPv4 address 
1.2.3.4, one would have to install /two/ firewall rules, one for IPv4 
1.2.3.4 and another for IPv4-mapped IPv6 ::ffff:1.2.3.4).

Unfortunately, this breaks a number of applications that depend on the 
RFC-specified default behavior (v6only=0).  GDM is one of them; Eclipse 
is another.  Re-enabling IPv4-mapped addresses is a quick (and dirty) 
fix to the breakage; however, one should be aware of the security 
implications of doing this (see above), and take additional steps to 
guard the system as necessary.

Hope this helped,
Eugene

Boris Samorodov wrote:
> Hello All!
>
>
> Way back before gnome-2.14 IPv6 and IPv4 were mutual exclusive.
> Current gdm-2.16.4 behaves the same:
>
> - gdm built with defaults listens only at udp6:
> %netstat -a | grep xdm
> udp6       0      0  *.xdmcp                *.*
>
> - disabling IPv6 helps to listen at udp4.
>
>
> WBR
>