It seems that Samba 3.5 has problems binding its socket when running on dual-stack Linux systems. This is what I am seeing in log.smbd, right after starting Samba:
[2011/11/30 18:42:18, 0] smbd/server.c:1141(main)
smbd version 3.5.11 started.
Copyright Andrew Tridgell and the Samba Team 1992-2010
[2011/11/30 18:42:20.269303, 0] smbd/server.c:501(smbd_open_one_socket)
smbd_open_once_socket: open_socket_in: Address already in use
[2011/11/30 18:42:20.269350, 0] smbd/server.c:501(smbd_open_one_socket)
smbd_open_once_socket: open_socket_in: Address already in use
I am seeing this on at least 3 different Linux distributions:
- CentOS 6.0 x86_64, samba-3.5.4-68.el6_0.2.x86_64
- Gentoo 10.0 x86_64, net-fs/samba-3.5.11
- Fedora 15 x86_64, samba-3.5.11-71.fc15.1.x86_64
You can work around the problem with sysctl net.ipv6.bindv6only=1.