Subject: Re: [iproute2] tc pedit modify ethhdr ?

From: jamal <[email-masked]>
Date: Wed, 24 Mar 2010 23:21:15 -0400

I put some effort in responding to you. Please put some
effort in testing it.

cheers,
jamal

On Wed, 2010-03-24 at 19:59 -0700, Xiaofei Wu wrote:
> 
> 
> I made a test like your example.
> The terminal prints:
> parse_cmd argc 20 set offset -14 length 2
> pack_key16: Final val 90000000 mask 0000ffff
> parse_cmd done argc 18 munge offset -16 length 2
> 
> what's the meaning of the above 3 lines;  It modify the value of  -16,-15,-14,-13 ,  or just modify -14,-13 ?
> If it modified -16,-15 ,   would it cause any problems?
> 
> Thanks.
> 
> 
> --
> Wu
> 
> 
> 
> ----- Original Message ----
> > but the size of ethhdr is 14 bytes, 14 is not multiple of 4 .
> > How to use 'tc ... pedit ...'  modify  a packet's   h_dest and h_source 
> > of ethhdr ?
> > Use ' ... pedit munge offset -14 u16 set 0x0090 munge offset -12 u32 set 0x9600030a ... '   or 
> > use ' ... pedit munge offset -16 u32 ... munge offset -12  ... '  ?
> > 
> 
> 0 is at ip header.
> dst MAC starts at -14
> src MAC at -8
> ethertype at -2
> 
> Example:
> tc filter add dev eth0 parent ffff: protocol ip prio 10 u32 \
> match ip src 192.168.1.10/32 flowid 1:2 \
> action pedit munge offset -14 u16 set 0x0000 \
> munge offset -12 u32 set 0x00010100 \
> munge offset -8 u32 set 0x0aaf0100 \
> munge offset -4 u32 set 0x0008ec06 pipe \
> action mirred egress redirect dev eth1
> 
> 
>