[LARTC] tc filter syntax (and general noobness)

[Vadtec <vadtec@vadtec.net>]

Ok,

After much research and e-mails to the list, I'm finally to the point 
where I have filtering setup properly.

Now, I'm trying to figure out tc filter so that I can classify packets 
on both eth0 and eth1.

So, lets take for example Samba traffic. I want to be sure that its 
being sent with relative speed so that my shares don't get lagged. And 
what the heck, its as good a place as any to start.

While I understand how to get the protocol number out of the header, I 
am having difficulty getting the rest of the field. Mostly, it has to do 
with offsets and which uX to use.

So, going off of what I think is correct, I have come up with this:

tc filter add dev eth1 parent 2: protocol ip prio 10 u32 match ip 
protocol 6 match u32 0xff534d42 0xffffffff at nexthdr+23 flowid 2:50

I seriously doubt this is the proper way to match a Samba header.

So  my question is this. How do I identify where the offset is for a 
given header? I assume that (going off the LARTC How To) I can look at 
output from wireshark and simply count to the field I am after. (This is 
how I figured out that tc filter add dev ppp14 parent 1:0 prio 10 u32 
match ip protocol 6 0xff match u8 0x10 0xff at nexthdr+13 flowid X:Y 
uses next header+13 to go from the protocol field to the ACK bit for the 
flags.)

The thing is. When I run this rule, none of the Samba traffic is being 
routed to 2:50... so obviously I'm not going something right.

Thanks for your help,


Vadtec
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