[Samba] Bug 6870 resurfaced in Samba 4.2.10

[L.P.H. van Belle]

Hai, 

Did you check if ifconfig still shows ipv6 adresses. ( even ::1 ) 

Can you check that. 

I have several with ipv6 on and severel only ipv4. 
As of 4.1.17+ i didnt see this happing here. Now on 4.4.5 
I think you have forgotten something. 

Greetz, 

Louis


> -----Oorspronkelijk bericht-----
> Van: samba [mailto:samba-bounces at lists.samba.org] Namens Rebecca Gellman
> via samba
> Verzonden: donderdag 13 oktober 2016 17:07
> Aan: samba at lists.samba.org
> Onderwerp: [Samba] Bug 6870 resurfaced in Samba 4.2.10
> 
> 
> 
> According to this bugzilla entry, bug 6870 has been fixed as of at least
> version 3.5:
> 
> https://bugzilla.samba.org/show_bug.cgi?id=6870
> 
> However, I assert that it is present in 4.2.10, which ships with Debian
> Jessie.
> 
> On my home network (IPv4 and IPv6), a box with Samba 4.2.10 with IPv6
> disabled (via sysctl), will fail to contact a DC because the IPv6
> connect fails immediately before the v4 connect has a chance to succeed.
> 
> 
> I determined this by strace'ing the "net ads workgroup" command, which
> resulted in the following:
> 
> 11:41:52 socket(PF_INET, SOCK_DGRAM, IPPROTO_IP) = 11 <0.000027>
> 11:41:52 fcntl(11, F_GETFL) = 0x2 (flags O_RDWR) <0.000015>
> 11:41:52 fcntl(11, F_SETFL, O_RDWR|O_NONBLOCK) = 0 <0.000016>
> 11:41:52 fcntl(11, F_GETFD) = 0 <0.000015>
> 11:41:52 fcntl(11, F_SETFD, FD_CLOEXEC) = 0 <0.000016>
> 11:41:52 connect(11, {sa_family=AF_INET, sin_port=htons(389),
> sin_addr=inet_addr("192.168.81.132")}, 16) = 0 <0.000050>
> 11:41:52 socket(PF_INET6, SOCK_DGRAM, IPPROTO_IP) = 12 <0.000025>
> 11:41:52 fcntl(12, F_GETFL) = 0x2 (flags O_RDWR) <0.000016>
> 11:41:52 fcntl(12, F_SETFL, O_RDWR|O_NONBLOCK) = 0 <0.000015>
> 11:41:52 fcntl(12, F_GETFD) = 0 <0.000016>
> 11:41:52 fcntl(12, F_SETFD, FD_CLOEXEC) = 0 <0.000015>
> 11:41:52 setsockopt(12, SOL_IPV6, IPV6_V6ONLY, [1], 4) = 0 <0.000018>
> 11:41:52 connect(12, {sa_family=AF_INET6, sin6_port=htons(389),
> inet_pton(AF_INET6, "2001:8b0:1627:1::2", &sin6_addr), sin6_flowinfo=0,
> sin6_scope_id=0}, 28) = -1 ENETUNREACH (Network is unreachable)
> <0.000032>
> 11:41:52 close(12) = 0 <0.000028>
> 11:41:52 close(11) = 0 <0.000024>
> 11:41:52 close(10) = 0 <0.000020>
> 11:41:52 fcntl(8, F_SETLKW, {type=F_RDLCK, whence=SEEK_SET, start=288,
> len=1}) = 0 <0.000021>
> 11:41:52 fcntl(8, F_SETLKW, {type=F_UNLCK, whence=SEEK_SET, start=288,
> len=1}) = 0 <0.000018>
> 11:41:52 fcntl(9, F_SETLKW, {type=F_WRLCK, whence=SEEK_SET, start=48,
> len=1}) = 0 <0.000019>
> 11:41:52 fcntl(9, F_SETLKW, {type=F_UNLCK, whence=SEEK_SET, start=48,
> len=1}) = 0 <0.000032>
> 11:41:52 fcntl(9, F_SETLKW, {type=F_WRLCK, whence=SEEK_SET, start=48,
> len=1}) = 0 <0.000019>
> 11:41:52 fcntl(9, F_SETLKW, {type=F_UNLCK, whence=SEEK_SET, start=48,
> len=1}) = 0 <0.000017>
> 11:41:52 write(2, "ads_connect: No logon servers\n", 30ads_connect: No
> logon servers
> 
> As you can see, sockets 11 and 12 are setup to contact the DC, 11 to v4,
> and 12 to v6. connect() on socket 11 is successful (returns 0), but
> connect() on socket 12 returns -1 due to "Network unreachable" - this is
> correct as the box in question does not have IPv6.
> 
> The attempt is abandoned (implied by the immediate closing of sockets 11
> and 12, and the writing of "No logon servers" to stderr) before any
> attempt is made to talk on socket 11 (v4).
> 
> After futzing the box to have an IPv6 address with appropriate routing,
> the attempt succeeds as expected. However, for reasons (too long to go
> into here) this is not a solution, only a means of proving the problem.
> 
> Since most DCs publish v6 records of some kind in DNS in an AD setup
> these days, it would seem that this behaviour could do with urgently
> fixing.
> 
> Any comments from the samba bods, or should I forward this on to
> samba-technical ?
> 
> Thanks
> 
> -- Rebecca Gellman
> 
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