In a firewall rule, what is included in "LAN net" for IPv6?
-
@jimp said in In a firewall rule, what is included in "LAN net" for IPv6?:
You already missed the point here. The DAD ND solicitation in your capture mentioned in your post earlier was sourced from ::, too, so pfSense would have dropped it and not responded without this fix.
????
PfSense should have nothing to do with a DAD from another device. It's simply a check by a device to see if an IP address is in use elsewhere. PfSense or rather the IPv6 stack below it should only respond in the event of a conflict with itself. Likewise NS and RS are below the pfSense level and handled within the FreeBSD IPv6 stack, not pfSense. In fact, you should be able to run FreeBSD or any other operating system and have this work, without any application, such as pfSense, running.
Now, take a look at the RFCs. In RFC 4861, under Neighbor Solicitation, it says:
"Source Address
Either an address assigned to the interface from
which this message is sent or (if Duplicate Address
Detection is in progress [ADDRCONF]) the
unspecified address."So, no problem using :: in NS.
Now, when we get to RFC 2461, where router solicitations are discussed we have:
"Source Address
An IP address assigned to the sending interface, or
the unspecified address if no address is assigned
to the sending interface."Sounds OK, but then we get to a curious situation. RAs are sent out to all nodes at interval or to a specific host, after a RS.
In the RA section:
"Destination Address
Typically the Source Address of an invoking Router
Solicitation or the all-nodes multicast address."But what address if the RS source is ::? That's not a valid destination address.
So, I'd question whether there should ever be a RA in response to an RS from an unspecified address.
Here's what Cisco says:
When an RA is sent in response to a router solicitation, the destination address in the RA message is the unicast address of the source of the router solicitation message.But then we get back to what source address, if the unspecified address cannot be used?
In my experience here, with both Linux and W10, the sequence is DAD from the unspecified address, followed by normal RS & RA using the valid link local address. Is that what's happening with that Samsung TV?
-
@jknott said in In a firewall rule, what is included in "LAN net" for IPv6?:
PfSense should have nothing to do with a DAD from another device. It's simply a check by a device to see if an IP address is in use elsewhere. PfSense or rather the IPv6 stack below it should only respond in the event of a conflict with itself. Likewise NS and RS are below the pfSense level and handled within the FreeBSD IPv6 stack, not pfSense. In fact, you should be able to run FreeBSD or any other operating system and have this work, without any application, such as pfSense, running.
Except those packets won't make it to the stack to be processed if they are blocked by pf, hence the problem.
-
@jimp said in In a firewall rule, what is included in "LAN net" for IPv6?:
Except those packets won't make it to the stack to be processed if they are blocked by pf, hence the problem.
Are you suggesting pfSense is blocking ICMP to itself? That's guaranteed to break SLAAC etc..
Can you ping the pfSense device on either IPv4 or IPv6? Does SLAAC work on your network without rules passing ICMPv6? -
@jknott said in In a firewall rule, what is included in "LAN net" for IPv6?:
@jimp said in In a firewall rule, what is included in "LAN net" for IPv6?:
Except those packets won't make it to the stack to be processed if they are blocked by pf, hence the problem.
Are you suggesting pfSense is blocking ICMP to itself? That's guaranteed to break SLAAC etc..
Can you ping the pfSense device on either IPv4 or IPv6? Does SLAAC work on your network without rules passing ICMPv6?That's the entire problem we've been actually discussing in this thread, which you seem to have missed entirely.
There is a default set of rules in pfSense to pass specific ICMPv6 packets at all times, for things like ND, RA, and so on. These are in place to ensure these features function properly even without a user adding rules to pass them. These rules did not pass from a source of
::
to the multicast destination. I added a rule to pass them so it will work.The full set of automatic default ICMPv6 rules (now)
https://github.com/pfsense/pfsense/blob/75cf92ffe93c7ea71cd5b432c369860b6e66a0d3/src/etc/inc/filter.inc#L3309The change I made in response to this thread:
https://github.com/pfsense/pfsense/commit/75cf92ffe93c7ea71cd5b432c369860b6e66a0d3#diff-84e675728564ed6deea6ee8002196c14 -
@jknott said in In a firewall rule, what is included in "LAN net" for IPv6?:
@jimp said in In a firewall rule, what is included in "LAN net" for IPv6?:
Except those packets won't make it to the stack to be processed if they are blocked by pf, hence the problem.
Are you suggesting pfSense is blocking ICMP to itself? That's guaranteed to break SLAAC etc..
Can you ping the pfSense device on either IPv4 or IPv6? Does SLAAC work on your network without rules passing ICMPv6?That is what I was observing and is the problem we are discussing.
In my opinion, if it is an internal service within pfsense, the user should not have to write a "pass" rule just to get it to the internal service within pfsense.
I, as a user, would not have anyway to know that it would go to pfsense only. I definitely would not want these packets to be forwarded on to other subnets because of my "pass" rule. Only the developers have this knowledge and should have it in the default rules.
-
@jimp said in In a firewall rule, what is included in "LAN net" for IPv6?:
That's the entire problem we've been actually discussing in this thread, which you seem to have missed entirely.
There is a default set of rules in pfSense to pass specific ICMPv6 packets at all times, for things like ND, RA, and so on. These are in place to ensure these features function properly even without a user adding rules to pass them. These rules did not pass from a source of :: to the multicast destination. I added a rule to pass them so it will work.As I mentioned above, I'd like to know what that TV is sending out. Does it correspond to what I'm seeing from Linux & Windows, that is DAD>RS>RA? Is that RS from :: valid? Is a router expected to send a RA when it doesn't have a valid RS source address? If so, where to? That info appears to be missing from the RFCs. I don't have the means to craft custom ICMP6 to test.
-
@jknott said in In a firewall rule, what is included in "LAN net" for IPv6?:
Those other people should be running Wireshark to see exactly what's happening. Packet Capture can also be used, but it's not as useful as Wireshark.
I just tried a capture with both. Packet Capture showed a total of 6 packets, compared to 9 with Wireshark. It also missed all 3 unspecified address DAD packets, including the one that preceded the RS. I'll have to try again after the new rules are available.
Since it appears pfSense is also missing the DAD packets, that could cause problems on a network with multiple routers, as each pfSense router will try to have a link local address of fe80::1:1 and not see the others when it runs DAD.
-
@jknott Periodically, the Samsung will send out:
ICMPv6 Src :: -> Dst ff02::2 Router Solicitation
If I have aforementioned pass rule, then pfsense immediately responds with a router advertisement icmpv6 packet
ICMPv6 Src fe80::1:1 -> Dst ff02::1 Router Advertisement
if not pass rule, pfsense doesn't respond in a timely manner, but maybe later on its own schedule.
-
I have seen Windows 10 do the same behavior at initial start up. But you have to be looking for it.
Samsung is more a Chatty Cathy, sort of like it has amnesia and forgets who and where it is.
-
@jknott On a related, but separate issue, I have noticed the same thing with other multicast, where pfsense should respond.
I have the Avahi package installed, and I see that the ipv6 multicast, ff02::fb (multicast DNS) is being blocked.
If I write a pass rule, I can see the pfsense respond with a DNS response, but otherwise it doesn't respond. So what happens then, is that the net device falls back to ipv4 multicast DNS and gets a response from pfsense via ipv4.
IPv6 uses link local (fe80::) and multicast for a LOT of the housekeeping activities on a link, and the pfsense in some cases is not participating until I write a "pass" rule to allow link local to multicast rule.
I would prefer not to do that since I worry that something could get passed on to other subnets inadvertently.
-
@isaacfl said in In a firewall rule, what is included in "LAN net" for IPv6?:
ICMPv6 Src :: -> Dst ff02::2 Router Solicitation
What does the source address show? You'll need Wireshark to see that. You can download the Packet Capture capture file to view it in Wireshark.
-
I just tried adding that rule and capturing the traffic as the test computer boots up. Wireshark shows the same as before, but Packet Capture now shows 14 packets captured, but none of them are DAD. Something strange is going on here. Packet Capture is running on the pfSense firewall and Wireshark on a computer connected via a managed switch, configured to mirror the traffic.
-
@jknott said in In a firewall rule, what is included in "LAN net" for IPv6?:
@isaacfl said in In a firewall rule, what is included in "LAN net" for IPv6?:
ICMPv6 Src :: -> Dst ff02::2 Router Solicitation
What does the source address show? You'll need Wireshark to see that. You can download the Packet Capture capture file to view it in Wireshark.
I am seeing on Wireshark, that the source address is ::
it is coming from the Samsung Mac address. -
@isaacfl said in In a firewall rule, what is included in "LAN net" for IPv6?:
I am seeing on Wireshark, that the source address is ::
it is coming from the Samsung Mac address.So, that brings us back to whether it's appropriate to use an unspecified address with a RS. Does it generate a RA when that rule is added? If so, what's the destination address?
-
@jknott said in In a firewall rule, what is included in "LAN net" for IPv6?:
I just tried adding that rule and capturing the traffic as the test computer boots up. Wireshark shows the same as before, but Packet Capture now shows 14 packets captured, but none of them are DAD. Something strange is going on here. Packet Capture is running on the pfSense firewall and Wireshark on a computer connected via a managed switch, configured to mirror the traffic.
What I use for testing, is a "pass" rule, IPv6 "any" to "ff02::0/16"
Then if you use Wireshark, you will see pfsense participating more on the link.
When you disable the rule, not so much pfsense. Also, a lot of the traffic gets repeated, trying to find the router.
-
@isaacfl said in In a firewall rule, what is included in "LAN net" for IPv6?:
ff02::0/16
I am getting more, just not the DAD. BTW, there's no difference between ff02::/16 and ff02::0/16. The :: simply means a string of 0 bits in the area specified.
When pfSense is updated to include the rule, they should test to make sure it is working properly. There shouldn't be any difference between PC and Wireshark.
-
@jknott said in In a firewall rule, what is included in "LAN net" for IPv6?:
@isaacfl said in In a firewall rule, what is included in "LAN net" for IPv6?:
ff02::0/16
I am getting more, just not the DAD. BTW, there's no difference between ff02::/16 and ff02::0/16. The :: simply means a string of 0 bits in the area specified.
yeah, I had been trying more restrictive multicast addresses in my alias as part of my testing,
-
@isaacfl said in In a firewall rule, what is included in "LAN net" for IPv6?:
I am seeing on Wireshark, that the source address is ::
it is coming from the Samsung Mac address.Does it also show a DAD? It's supposed to be all but mandatory. Here's what RFC 4862 says:
"5.4. Duplicate Address Detection
Duplicate Address Detection MUST be performed on all unicast
addresses prior to assigning them to an interface, regardless of
whether they are obtained through stateless autoconfiguration,
DHCPv6, or manual configuration, with the following exceptions:-
An interface whose DupAddrDetectTransmits variable is set to zero
does not perform Duplicate Address Detection. -
Duplicate Address Detection MUST NOT be performed on anycast
addresses (note that anycast addresses cannot syntactically be
distinguished from unicast addresses). -
Each individual unicast address SHOULD be tested for uniqueness.
Note that there are implementations deployed that only perform
Duplicate Address Detection for the link-local address and skip
the test for the global address that uses the same interface
identifier as that of the link-local address." ...
I doubt a TV would have that variable set to 0
-
-
@jknott If I unplug the tv then back on, I see all what you are describing.
Once it is operating normally. I will see about every minute and a half I see about 6 or 7 ICMPv6 packets between the Samsung and pfSense:
Samsung sends:
[::] to [ff02::2] Length 63 Router Solicitationpfsense responds:
[fe80::1:1] to [ff02::1] Length 198 Router Advertisement (includes prefix, domain, DNS, etc.)Samsung responds with 2 packets, using it's link local address:
[fe80::56bd:79ff:fe17:54b] to [ff02::16] Length 90 Multicast Listener Report Message v2pfsense responds:
[fe80:1:1] to [ff02::16] Length 90 Multicast Listener Report Message v2That is the only time I see the [::] used as a source address.
It is some sort of joining a multicast conversation. -
@isaacfl I mistyped the record length above 63 should be 62.