Samba and ipv6

SimoB

Hey hi, I had troubles to access a share on my Solus machine from a Win10 1806.

Digging in the samba log (/var/log/samba/log.smbd ) I see a lot of this:

[2019/05/31 12:48:31.921662,  0] ../lib/util/access.c:365(allow_access)
  Denied connection from fe80::c476:a155:d616:469a (fe80::c476:a155:d616:469a)
[2019/05/31 12:48:31.921735,  1] ../source3/smbd/process.c:3822(smbd_add_connection)
  Connection denied from ipv6:fe80::c476:a155:d616:469a:61518 to ipv6:fe80::bc27:6d7a:e1ee:421c:445

Also this problem only happen if I try to connect using the domain "\\MY-PC\MyShare"

Using the IP "\\192.168.1.123\MyShare" works fine.

To make it works I had to add this to my smb.conf

interfaces = 127.0.0.1 enp1s0
bind interfaces only = yes

So is the default Solus 4 samba config ok? is that ipv6 related?

p.s.
I did not find anything about this problem in https://getsol.us/articles/software/samba/en/

Staudey

This sounds like a job for @ermo 🙂

Justin

Honestly if you don't use ipv6 I'd disable it on your router or DHCP server.

SimoB

I don't think disable ipv6 from the router is a solution, 100% of routers sold in recent years comes with ipv6 enabled by default, also I'm not sure if is possible to disable it at all on my router, I have this radio button ipv4/ipv6, it has always been on ipv4, I've never really messed with ipv6, all my local net is ipv4, also never had this specific samba problem with other linux distros 🤔

Justin

ipv6 isn't really necessary inside your home network. Not even the biggest organisations on Earth need ipv6 internally. It was created to solve a WAN side problem, and it's still not even needed as CGNAT and other technologies have continued to keep ipv4 viable online.

SimoB

Justin Ok, the point is that I did nothing to enable ipv6, either on my router or on Solus, I don't know why Samba is using ipv6!

ermo

Samba tries to resolve old NetBIOS names (e.g. \\MY-PC\) via NetBIOS over DNS.

I agree that this looks a little weird. The "problem" (if one can call it that) is likely to be that hosts are resolved to AAAA (IPv6 DNS) records first instead of A (IPv4 DNS) records.

I personally set my network cards to "link local only" IPv6 addresses on my home network to avoid IPv6 DNS issues (not sure why this works, but it does for me).

Another option is to use your host's proper dns name (e.g. smb://myhost.lan/myshare) instead of using NetBIOS.

SimoB

ermo So should I select link-local as method under the IPv6 tab?

Justin

IPv6 is often enabled on newer routers but still causes issues as not all software is ready for it.

SimoB

As a side note, why in the Wired tab "allow auto-negotiation" was not the default? I was connected at 100Mbit insted of 1Gbit ☹️

Justin

SimoB Mine defaulted to 1gbps in Budgie so not sure why yours would be defaulting to 100mbps (I'm assuming here).

ermo

@SimoB

This reply is (very) late, but you could try adding hosts allow = 127. 192.168.1 fe80:: to your /etc/samba/smb.conf file.

The default Solus file doesn't allow access from IPv6 hosts, which is perhaps an oversight and should probably be addressed. With the above configuration, it is assumed that your internal LAN resides on the 192.168.1.0/24 network.

The fe80:: part means Link-Local IPv6 addresses. These addresses can't be routed, just like RFC 1918 IPv4 addresses (e.g. 192.168.1.0/24) can't be routed either.