Re: [Cerowrt-devel] squash/ignore DSCP and mangle table questions

[leetminiwheat <LeetMiniWheat@gmail.com>]

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Actually I think I figured out the last part,

iptables -t mangle -A RECLASS_sw10 -p tcp -m tcp --sport 6484 -m conntrack
--ctstate NEW,RELATED,ESTABLISHED -j DSCP --set-dscp 0x2e
iptables -t mangle -A RECLASS_sw10 -p tcp -m tcp --dport 6484 -m conntrack
--ctstate NEW,RELATED,ESTABLISHED -j DSCP --set-dscp 0x2e
iptables -t mangle -A RECLASS_sw10 -p udp -m udp --sport 6484 -m conntrack
--ctstate NEW,RELATED,ESTABLISHED -j DSCP --set-dscp 0x2e
iptables -t mangle -A RECLASS_sw10 -p udp -m udp --dport 6484 -m conntrack
--ctstate NEW,RELATED,ESTABLISHED -j DSCP --set-dscp 0x2e

Probably not a good idea to do conntracking here, but it should only be
matching that specific interface and port anyways.

On Mon, Apr 13, 2015 at 6:27 AM, leetminiwheat <LeetMiniWheat@gmail.com>
wrote:

> Thanks for the reply,
>
>
> On Mon, Apr 13, 2015 at 3:36 AM, Sebastian Moeller <moeller0@gmx.de>
> wrote:
>
> >         "Ignore DSCP on ingress”, this basically uses an 1-tier HTB
> shaper on ingress, DSCP marks in the packets are simply ignored, but not
> touched.
>
> So if I understand this correctly, this means they're kind of in
> passthrough mode on ignore but the qdiscs don't act on them due to no
> iptables MARKing? And If *not* ignoring DSCP on ingress, they're still
> passed through untouched but prioritized internally with the qdiscs?
>
> >         "Squash DSCP on inbound packets (ingress):” this will replace
> all DSCP marks with 0x0 (I believe), but only after the ingress qdisc.
> > In essence this means you can actually interpret ingress DSCP marks from
> upstream ("Ignore DSCP on ingress” set to ALLOW) but wipe them after the
> ingress shaping (with "Squash DSCP on inbound packets (ingress);” active).
> So the default should be “Ignore DSCP on ingress” and Squash (the second
> can be argued, as long as no one bases routing decisions on the marks they
> do not hurt). The rest of your questions are beyond my expertise...
>
> Hmm, why would we want to remove all DSCP on output then? I assume many
> ISPs and routers will squash them anyways, but wouldn't it serve *some*
> purpose to differentiate between different traffic types?
>
>
> Also, regarding my mangling questions I think I figured out the correct
> chains to insert my rules in. mangle PREROUTING and mangle POSTROUTING
> because both of those have a jump at the end to a chain that MARKs for
> qdiscs based on DSCP values. They appear to be working since I see the MARK
> rules counting upward. I assume PRE and POST go through FORWARD anyways so
> it's redundant, and using FORWARD only didn't appear to be working. I've
> ended up with this:
>
> # Mangle sw10 packets to reclassify mumble traffic. Hopefully this passes
> through DSCP so WMM can recognize 0x2e as VoIP traffic
> iptables -t mangle -N RECLASS_sw10
> iptables -t mangle -A RECLASS_sw10 -p tcp -m tcp --sport 6484  -j DSCP
> --set-dscp 0x2e
> iptables -t mangle -A RECLASS_sw10 -p tcp -m tcp --dport 6484  -j DSCP
> --set-dscp 0x2e
> iptables -t mangle -A RECLASS_sw10 -p udp -m udp --sport 6484 -j DSCP
> --set-dscp 0x2e
> iptables -t mangle -A RECLASS_sw10 -p udp -m udp --dport 6484 -j DSCP
> --set-dscp 0x2e
> iptables -t mangle -I PREROUTING -i sw10 -j RECLASS_sw10
> iptables -t mangle -I POSTROUTING -o sw10 -j RECLASS_sw10
>
> # Mangle gw00 to reclassify guest as low priority
> iptables -t mangle -N RECLASS_gw00
> iptables -t mangle -A RECLASS_gw00 -j DSCP --set-dscp 0x08
> iptables -t mangle -I PREROUTING -i gw00 -j RECLASS_gw00
> iptables -t mangle -I POSTROUTING -o gw00 -j RECLASS_gw00
>
>
> However, I'm not sure how the port specific rules handle
> RELATED,ESTABLISHED because I believe the initial connection is done on
> port 6484 but then it uses a random high port. I'm not sure how I could add
> a RELATED,ESTABLISHED match to connections on port 6484 to my custom zone
> that reclassifies to 0x2e to catch *all* traffic related to it.
>
>

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