[Cerowrt-devel] conntrack and ipv6

[Cerowrt-devel] conntrack and ipv6

[Dave Täht]

It is generally my hope that ipv6 nat will not be widely deployed.

Firewalls will be stateful instead, and thus there would be no need to
access the conntrack information for ipv6 in cake.

I'm not sure, however, to
what extent ipv6 conntrack is in openwrt today, certainly udp and tcp,
"in" is essentially blocked by default, and needs to be triggered by an
outgoing message. Similarly I'm unfamiliar with the state of ipv6 upnp
and pcp support in openwrt or client applications at present.


On 6/30/16 10:33 AM, Kevin Darbyshire-Bryant wrote:
> 
> 
> On 02/06/16 13:29, Jonathan Morton wrote:
>>> On 2 Jun, 2016, at 14:09, Kevin Darbyshire-Bryant
>>> <kevin@darbyshire-bryant.me.uk> wrote:
>>>
>>> Cake uses the flow dissector API to do flow hashing...including per
>>> host flows for dual/triple isolation.  The unfortunate bit is that
>>> the qdisc inevitably gets placed after packets have been NATed on
>>> egress and before they've been de-NATed on ingress.
>>>
>>> When mentioned before Johnathan said "flow dissector ideally needs to
>>> be tweaked to do this" or words to that effect.
>>>
>>> I'd like to progress that idea...the thought of me kernel programming
>>> should horrify everyone but really I'm asking for help in being
>>> pointed in the right direction to ask for help...and go from there :-)
>> I believe Linux does NAT using a “connection tracker” subsystem.  That
>> would contain the necessary data for resolving NAT equivalents.  I
>> don’t know how easy it is to query in a qdisc context, though.
> Imagine my joy of discovering http://fatooh.org/esfq-2.6/  - someone has
> already bl**dy done it....and I found it lurking in LEDE as part of a
> patch.
> 
> So there relevant bits are something of the order:
> 
> 
> +#ifdef CONFIG_NET_SCH_ESFQ_NFCT
> +       enum ip_conntrack_info ctinfo;
> +       struct nf_conn *ct = nf_ct_get(skb, &ctinfo);
> +#endif
> 
> +#ifdef CONFIG_NET_SCH_ESFQ_NFCT
> +       /* defaults if there is no conntrack info */
> +       info.ctorigsrc = info.src;
> +       info.ctorigdst = info.dst;
> +       info.ctreplsrc = info.dst;
> +       info.ctrepldst = info.src;
> +       /* collect conntrack info */
> +       if (ct && ct != &nf_conntrack_untracked) {
> +               if (skb->protocol == __constant_htons(ETH_P_IP)) {
> +                       info.ctorigsrc =
> ct->tuplehash[IP_CT_DIR_ORIGINAL].tuple.src.u3.ip;
> +                       info.ctorigdst =
> ct->tuplehash[IP_CT_DIR_ORIGINAL].tuple.dst.u3.ip;
> +                       info.ctreplsrc =
> ct->tuplehash[IP_CT_DIR_REPLY].tuple.src.u3.ip;
> +                       info.ctrepldst =
> ct->tuplehash[IP_CT_DIR_REPLY].tuple.dst.u3.ip;
> +               }
> +               else if (skb->protocol == __constant_htons(ETH_P_IPV6)) {
> +                       /* Again, hash ipv6 addresses into a single u32. */
> +                       info.ctorigsrc =
> jhash2(ct->tuplehash[IP_CT_DIR_ORIGINAL].tuple.src.u3.ip6, 4,
> q->perturbation);
> +                       info.ctorigdst =
> jhash2(ct->tuplehash[IP_CT_DIR_ORIGINAL].tuple.dst.u3.ip6, 4,
> q->perturbation);
> +                       info.ctreplsrc =
> jhash2(ct->tuplehash[IP_CT_DIR_REPLY].tuple.src.u3.ip6, 4,
> q->perturbation);
> +                       info.ctrepldst =
> jhash2(ct->tuplehash[IP_CT_DIR_REPLY].tuple.dst.u3.ip6, 4,
> q->perturbation);
> +               }
> +
> +       }
> +#endif
> 
> I'd rip out the IPv6 conntrack stuff as I'm much more concerned by
> handling IPv4 NAT.  And I'm not sure how to get it into cake's host
> handling yet but....
> 
> I can feel an experiment and hackery coming on later today :-)
> 
> Am overjoyed!
> _______________________________________________
> Cake mailing list
> Cake@lists.bufferbloat.net
> https://lists.bufferbloat.net/listinfo/cake

Re: [Cerowrt-devel] [Cake] conntrack and ipv6

[moeller0]

Hi Dave,


> On Jul 2, 2016, at 14:47 , Dave Täht <dave@taht.net> wrote:
> 
> It is generally my hope that ipv6 nat will not be widely deployed.
> 
> Firewalls will be stateful instead, and thus there would be no need to
> access the conntrack information for ipv6 in cake.

	I would hope that IPv6 NAT would not re-map ports but instead simply “hide” stuff behind the prefix, so internal hosts would still be differentiated by the remaining 64bits (since individual hosts are supposed to use multiple IPv6 addresses I would be amazed if IPv6NAT would hide behind a /128…). The bigger fairness issue is that individual host can use basically as many IPs as they want and per-IP fairness will not be the right thing anymore anf then all we can use is per-MAC, so no internal routers permitted anymore…

> 
> I'm not sure, however, to
> what extent ipv6 conntrack is in openwrt today, certainly udp and tcp,
> "in" is essentially blocked by default, and needs to be triggered by an
> outgoing message. Similarly I'm unfamiliar with the state of ipv6 upnp
> and pcp support in openwrt or client applications at present.
> 
> 
> On 6/30/16 10:33 AM, Kevin Darbyshire-Bryant wrote:
>> 
>> 
>> On 02/06/16 13:29, Jonathan Morton wrote:
>>>> On 2 Jun, 2016, at 14:09, Kevin Darbyshire-Bryant
>>>> <kevin@darbyshire-bryant.me.uk> wrote:
>>>> 
>>>> Cake uses the flow dissector API to do flow hashing...including per
>>>> host flows for dual/triple isolation.  The unfortunate bit is that
>>>> the qdisc inevitably gets placed after packets have been NATed on
>>>> egress and before they've been de-NATed on ingress.
>>>> 
>>>> When mentioned before Johnathan said "flow dissector ideally needs to
>>>> be tweaked to do this" or words to that effect.
>>>> 
>>>> I'd like to progress that idea...the thought of me kernel programming
>>>> should horrify everyone but really I'm asking for help in being
>>>> pointed in the right direction to ask for help...and go from there :-)
>>> I believe Linux does NAT using a “connection tracker” subsystem.  That
>>> would contain the necessary data for resolving NAT equivalents.  I
>>> don’t know how easy it is to query in a qdisc context, though.
>> Imagine my joy of discovering http://fatooh.org/esfq-2.6/  - someone has
>> already bl**dy done it....and I found it lurking in LEDE as part of a
>> patch.
>> 
>> So there relevant bits are something of the order:
>> 
>> 
>> +#ifdef CONFIG_NET_SCH_ESFQ_NFCT
>> +       enum ip_conntrack_info ctinfo;
>> +       struct nf_conn *ct = nf_ct_get(skb, &ctinfo);
>> +#endif
>> 
>> +#ifdef CONFIG_NET_SCH_ESFQ_NFCT
>> +       /* defaults if there is no conntrack info */
>> +       info.ctorigsrc = info.src;
>> +       info.ctorigdst = info.dst;
>> +       info.ctreplsrc = info.dst;
>> +       info.ctrepldst = info.src;
>> +       /* collect conntrack info */
>> +       if (ct && ct != &nf_conntrack_untracked) {
>> +               if (skb->protocol == __constant_htons(ETH_P_IP)) {
>> +                       info.ctorigsrc =
>> ct->tuplehash[IP_CT_DIR_ORIGINAL].tuple.src.u3.ip;
>> +                       info.ctorigdst =
>> ct->tuplehash[IP_CT_DIR_ORIGINAL].tuple.dst.u3.ip;
>> +                       info.ctreplsrc =
>> ct->tuplehash[IP_CT_DIR_REPLY].tuple.src.u3.ip;
>> +                       info.ctrepldst =
>> ct->tuplehash[IP_CT_DIR_REPLY].tuple.dst.u3.ip;
>> +               }
>> +               else if (skb->protocol == __constant_htons(ETH_P_IPV6)) {
>> +                       /* Again, hash ipv6 addresses into a single u32. */
>> +                       info.ctorigsrc =
>> jhash2(ct->tuplehash[IP_CT_DIR_ORIGINAL].tuple.src.u3.ip6, 4,
>> q->perturbation);
>> +                       info.ctorigdst =
>> jhash2(ct->tuplehash[IP_CT_DIR_ORIGINAL].tuple.dst.u3.ip6, 4,
>> q->perturbation);
>> +                       info.ctreplsrc =
>> jhash2(ct->tuplehash[IP_CT_DIR_REPLY].tuple.src.u3.ip6, 4,
>> q->perturbation);
>> +                       info.ctrepldst =
>> jhash2(ct->tuplehash[IP_CT_DIR_REPLY].tuple.dst.u3.ip6, 4,
>> q->perturbation);
>> +               }
>> +
>> +       }
>> +#endif
>> 
>> I'd rip out the IPv6 conntrack stuff as I'm much more concerned by
>> handling IPv4 NAT.  And I'm not sure how to get it into cake's host
>> handling yet but....
>> 
>> I can feel an experiment and hackery coming on later today :-)
>> 
>> Am overjoyed!
>> _______________________________________________
>> Cake mailing list
>> Cake@lists.bufferbloat.net
>> https://lists.bufferbloat.net/listinfo/cake
> _______________________________________________
> Cake mailing list
> Cake@lists.bufferbloat.net
> https://lists.bufferbloat.net/listinfo/cake

Re: [Cerowrt-devel] [Cake] conntrack and ipv6

[David Lang]

[-- Attachment #1: Type: TEXT/PLAIN, Size: 4451 bytes --]

On Sat, 2 Jul 2016, Dave Täht wrote:

> It is generally my hope that ipv6 nat will not be widely deployed.
>
> Firewalls will be stateful instead, and thus there would be no need to
> access the conntrack information for ipv6 in cake.

well, conntrack is the way that the firewall handles it's state. Conntrack also 
has features to let you sync it's state from one system to it's backup so that 
failover maintains the state.

> I'm not sure, however, to
> what extent ipv6 conntrack is in openwrt today, certainly udp and tcp,
> "in" is essentially blocked by default, and needs to be triggered by an
> outgoing message.

It's compiled into the kernel and on by default (I fight to turn it off for 
Scale where I don't need to maintain state in the APs as they don't do any 
firewalling)

David Lang

> Similarly I'm unfamiliar with the state of ipv6 upnp
> and pcp support in openwrt or client applications at present.
>
>
> On 6/30/16 10:33 AM, Kevin Darbyshire-Bryant wrote:
>> 
>> 
>> On 02/06/16 13:29, Jonathan Morton wrote:
>>>> On 2 Jun, 2016, at 14:09, Kevin Darbyshire-Bryant
>>>> <kevin@darbyshire-bryant.me.uk> wrote:
>>>>
>>>> Cake uses the flow dissector API to do flow hashing...including per
>>>> host flows for dual/triple isolation.  The unfortunate bit is that
>>>> the qdisc inevitably gets placed after packets have been NATed on
>>>> egress and before they've been de-NATed on ingress.
>>>>
>>>> When mentioned before Johnathan said "flow dissector ideally needs to
>>>> be tweaked to do this" or words to that effect.
>>>>
>>>> I'd like to progress that idea...the thought of me kernel programming
>>>> should horrify everyone but really I'm asking for help in being
>>>> pointed in the right direction to ask for help...and go from there :-)
>>> I believe Linux does NAT using a “connection tracker” subsystem.  That
>>> would contain the necessary data for resolving NAT equivalents.  I
>>> don’t know how easy it is to query in a qdisc context, though.
>> Imagine my joy of discovering http://fatooh.org/esfq-2.6/  - someone has
>> already bl**dy done it....and I found it lurking in LEDE as part of a
>> patch.
>> 
>> So there relevant bits are something of the order:
>> 
>> 
>> +#ifdef CONFIG_NET_SCH_ESFQ_NFCT
>> +       enum ip_conntrack_info ctinfo;
>> +       struct nf_conn *ct = nf_ct_get(skb, &ctinfo);
>> +#endif
>> 
>> +#ifdef CONFIG_NET_SCH_ESFQ_NFCT
>> +       /* defaults if there is no conntrack info */
>> +       info.ctorigsrc = info.src;
>> +       info.ctorigdst = info.dst;
>> +       info.ctreplsrc = info.dst;
>> +       info.ctrepldst = info.src;
>> +       /* collect conntrack info */
>> +       if (ct && ct != &nf_conntrack_untracked) {
>> +               if (skb->protocol == __constant_htons(ETH_P_IP)) {
>> +                       info.ctorigsrc =
>> ct->tuplehash[IP_CT_DIR_ORIGINAL].tuple.src.u3.ip;
>> +                       info.ctorigdst =
>> ct->tuplehash[IP_CT_DIR_ORIGINAL].tuple.dst.u3.ip;
>> +                       info.ctreplsrc =
>> ct->tuplehash[IP_CT_DIR_REPLY].tuple.src.u3.ip;
>> +                       info.ctrepldst =
>> ct->tuplehash[IP_CT_DIR_REPLY].tuple.dst.u3.ip;
>> +               }
>> +               else if (skb->protocol == __constant_htons(ETH_P_IPV6)) {
>> +                       /* Again, hash ipv6 addresses into a single u32. */
>> +                       info.ctorigsrc =
>> jhash2(ct->tuplehash[IP_CT_DIR_ORIGINAL].tuple.src.u3.ip6, 4,
>> q->perturbation);
>> +                       info.ctorigdst =
>> jhash2(ct->tuplehash[IP_CT_DIR_ORIGINAL].tuple.dst.u3.ip6, 4,
>> q->perturbation);
>> +                       info.ctreplsrc =
>> jhash2(ct->tuplehash[IP_CT_DIR_REPLY].tuple.src.u3.ip6, 4,
>> q->perturbation);
>> +                       info.ctrepldst =
>> jhash2(ct->tuplehash[IP_CT_DIR_REPLY].tuple.dst.u3.ip6, 4,
>> q->perturbation);
>> +               }
>> +
>> +       }
>> +#endif
>> 
>> I'd rip out the IPv6 conntrack stuff as I'm much more concerned by
>> handling IPv4 NAT.  And I'm not sure how to get it into cake's host
>> handling yet but....
>> 
>> I can feel an experiment and hackery coming on later today :-)
>> 
>> Am overjoyed!
>> _______________________________________________
>> Cake mailing list
>> Cake@lists.bufferbloat.net
>> https://lists.bufferbloat.net/listinfo/cake
> _______________________________________________
> Cake mailing list
> Cake@lists.bufferbloat.net
> https://lists.bufferbloat.net/listinfo/cake

Re: [Cerowrt-devel] [Cake] conntrack and ipv6

[Jonathan Morton]

> On 3 Jul, 2016, at 09:16, David Lang <david@lang.hm> wrote:
> 
>> It is generally my hope that ipv6 nat will not be widely deployed.
>> 
>> Firewalls will be stateful instead, and thus there would be no need to
>> access the conntrack information for ipv6 in cake.
> 
> well, conntrack is the way that the firewall handles it's state. Conntrack also has features to let you sync it's state from one system to it's backup so that failover maintains the state.

Yes, but the point is that in a stateful firewall (as opposed to NAT) no changes to IP addresses occur while traversing the router.  Cake can therefore see the correct addresses without probing conntrack data.

There's still a huge number of people on IPv4 NAT though.

 - Jonathan Morton

Re: [Cerowrt-devel] conntrack and ipv6

[moeller0]

Hi Dave,


> On Jul 2, 2016, at 14:47 , Dave Täht <dave@taht.net> wrote:
> 
> It is generally my hope that ipv6 nat will not be widely deployed.

	I checked a few RFCs and both NAT66 (https://tools.ietf.org/html/draft-mrw-behave-nat66-02) or NPTv6 (https://tools.ietf.org/html/rfc6296) only seem to change the prefix-part while maintaining the last 64 bit of IPv6 addresses so that cake will see different (somewhat) stable IPv6 addresses (probably just as stable as IPv6 privacy addresses can be), so internal-IP fairness should not require conntrack at all. They also thankfully leave the port numbers alone, maening that neither udp nor tcp headers typically need to be touched, nice…
        Now, if someone should come up with NATv6/128 that hides all internal addresses behind a single /128 and does the old port remapping song and dance, I believe that person should be entitled to keep all the pieces…


> 
> Firewalls will be stateful instead, and thus there would be no need to
> access the conntrack information for ipv6 in cake.
> 
> I'm not sure, however, to
> what extent ipv6 conntrack is in openwrt today, certainly udp and tcp,
> "in" is essentially blocked by default, and needs to be triggered by an
> outgoing message. Similarly I'm unfamiliar with the state of ipv6 upnp
> and pcp support in openwrt or client applications at present.
> 
> 
> On 6/30/16 10:33 AM, Kevin Darbyshire-Bryant wrote:
>> 
>> 
>> On 02/06/16 13:29, Jonathan Morton wrote:
>>>> On 2 Jun, 2016, at 14:09, Kevin Darbyshire-Bryant
>>>> <kevin@darbyshire-bryant.me.uk> wrote:
>>>> 
>>>> Cake uses the flow dissector API to do flow hashing...including per
>>>> host flows for dual/triple isolation.  The unfortunate bit is that
>>>> the qdisc inevitably gets placed after packets have been NATed on
>>>> egress and before they've been de-NATed on ingress.
>>>> 
>>>> When mentioned before Johnathan said "flow dissector ideally needs to
>>>> be tweaked to do this" or words to that effect.
>>>> 
>>>> I'd like to progress that idea...the thought of me kernel programming
>>>> should horrify everyone but really I'm asking for help in being
>>>> pointed in the right direction to ask for help...and go from there :-)
>>> I believe Linux does NAT using a “connection tracker” subsystem.  That
>>> would contain the necessary data for resolving NAT equivalents.  I
>>> don’t know how easy it is to query in a qdisc context, though.
>> Imagine my joy of discovering http://fatooh.org/esfq-2.6/  - someone has
>> already bl**dy done it....and I found it lurking in LEDE as part of a
>> patch.
>> 
>> So there relevant bits are something of the order:
>> 
>> 
>> +#ifdef CONFIG_NET_SCH_ESFQ_NFCT
>> +       enum ip_conntrack_info ctinfo;
>> +       struct nf_conn *ct = nf_ct_get(skb, &ctinfo);
>> +#endif
>> 
>> +#ifdef CONFIG_NET_SCH_ESFQ_NFCT
>> +       /* defaults if there is no conntrack info */
>> +       info.ctorigsrc = info.src;
>> +       info.ctorigdst = info.dst;
>> +       info.ctreplsrc = info.dst;
>> +       info.ctrepldst = info.src;
>> +       /* collect conntrack info */
>> +       if (ct && ct != &nf_conntrack_untracked) {
>> +               if (skb->protocol == __constant_htons(ETH_P_IP)) {
>> +                       info.ctorigsrc =
>> ct->tuplehash[IP_CT_DIR_ORIGINAL].tuple.src.u3.ip;
>> +                       info.ctorigdst =
>> ct->tuplehash[IP_CT_DIR_ORIGINAL].tuple.dst.u3.ip;
>> +                       info.ctreplsrc =
>> ct->tuplehash[IP_CT_DIR_REPLY].tuple.src.u3.ip;
>> +                       info.ctrepldst =
>> ct->tuplehash[IP_CT_DIR_REPLY].tuple.dst.u3.ip;
>> +               }
>> +               else if (skb->protocol == __constant_htons(ETH_P_IPV6)) {
>> +                       /* Again, hash ipv6 addresses into a single u32. */
>> +                       info.ctorigsrc =
>> jhash2(ct->tuplehash[IP_CT_DIR_ORIGINAL].tuple.src.u3.ip6, 4,
>> q->perturbation);
>> +                       info.ctorigdst =
>> jhash2(ct->tuplehash[IP_CT_DIR_ORIGINAL].tuple.dst.u3.ip6, 4,
>> q->perturbation);
>> +                       info.ctreplsrc =
>> jhash2(ct->tuplehash[IP_CT_DIR_REPLY].tuple.src.u3.ip6, 4,
>> q->perturbation);
>> +                       info.ctrepldst =
>> jhash2(ct->tuplehash[IP_CT_DIR_REPLY].tuple.dst.u3.ip6, 4,
>> q->perturbation);
>> +               }
>> +
>> +       }
>> +#endif
>> 
>> I'd rip out the IPv6 conntrack stuff as I'm much more concerned by
>> handling IPv4 NAT.  And I'm not sure how to get it into cake's host
>> handling yet but....
>> 
>> I can feel an experiment and hackery coming on later today :-)
>> 
>> Am overjoyed!
>> _______________________________________________
>> Cake mailing list
>> Cake@lists.bufferbloat.net
>> https://lists.bufferbloat.net/listinfo/cake
> _______________________________________________
> Cerowrt-devel mailing list
> Cerowrt-devel@lists.bufferbloat.net
> https://lists.bufferbloat.net/listinfo/cerowrt-devel