Hi Anton, > You are trying to use the offset. It's valid only after linking. > > See http://ace-host.stuart.id.au/russell/files/tc/doc/cls_u32.txt for > details and examples. thank you for your reply :) And thanks for the link Remy got nDPI kernel module compiled and I have included all this on our router. Seems to work so far. Even nDPI is great, RDP detection needs some tweaks, as it covers all RDP codecs including video, which I did not want to match. I actually limit the length as well from minimum 20 up to 200 bytes. I also could do the length test in u32, as I have this information in UDP. But some codecs have a dynamic PT, so I can not stay with u32 and need nDPI ;-) Thanks for all your help Christian > 2014-04-10 12:57 GMT+04:00 Christian Rößner <cr@xxxxxxx>: >> Hi, >> >> this is my first post to this list. >> >> I try to match several RTPv2 codecs with tc u32 and I ended up with the following: >> >> tc filter add dev mydevice protocol ip parent 1:0 pref 3 u32 \ >> match ip protocol 0x11 0xFF \ >> match u16 0x8008 0xC07F at 28 \ >> flowid 1:110 >> >> So far this works. It means (at least I hope so): >> >> - match UDP, >> - match the first two bytes in the UDP payload, which are part of the RTP header >> - first two bits say „version 2“ RTP >> - last 7 bits encode the codec. In this example G.711 PCMA >> >> So now this code is just working for IPv4. And I would like to have a more generic one using nexthdr. So I tried: >> >> tc filter add dev mydevice protocol ip parent 1:0 pref 3 u32 \ >> match ip protocol 0x11 0xFF \ >> match u16 0x8008 0xC07F at nexthdr+4 \ >> flowid 1:110 >> >> Problem with this is that it matches packets, but when doing a test call with VoIP I can see that it does not match RTP traffic but some wrong traffic. So I guess my „nexthdr+4“ is wrong. I thought that the nexthdr depends on the selector u16 and therefor needs to be 4. 4*16=64, which should be 8 bytes offset to UDP, which is the beginning of the payload, isn’t it? >> >> Can someone help me fixing this rule? Thanks in advance -Christian Rößner -- [*] sys4 AG http://sys4.de, +49 (89) 30 90 46 64 Franziskanerstraße 15, 81669 München Sitz der Gesellschaft: München, Amtsgericht München: HRB 199263 Vorstand: Patrick Ben Koetter, Marc Schiffbauer Aufsichtsratsvorsitzender: Florian Kirstein
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