Gentoo Forums
Gentoo Forums
Gentoo Forums
Quick Search: in
using tc's match to find ACK packets
View unanswered posts
View posts from last 24 hours

 
Reply to topic    Gentoo Forums Forum Index Networking & Security
View previous topic :: View next topic  
Author Message
tnt
Veteran
Veteran


Joined: 27 Feb 2004
Posts: 1129

PostPosted: Sat Sep 15, 2012 12:55 pm    Post subject: using tc's match to find ACK packets Reply with quote

in LATRC we are advised to use the following to find ACK packets:


Code:
tc filter add dev ppp14 parent 1:0 protocol ip prio 10 u32 \
     match ip protocol 6 0xff \
     match u8 0x10 0xff at nexthdr+13 \
     match u16 0x0000 0xffc0 at 2 \
     flowid 1:3


where part of the code
Code:
match u8 0x10 0xff at nexthdr+13


should check if ACK bit is set.
but, as mask given to that match is 0xff, it returns "true" just if ONLY ACK is set.
is this right, or should this filter have mask 0x10 to match if, besides other bits, also ACK is set?

Code:
match u8 0x10 0x10 at nexthdr+13


http://lartc.org/howto/lartc.adv-filter.html
http://www.compago.it/images/stories/TCP_Header.png

thx.
_________________
gentoo user
Back to top
View user's profile Send private message
Display posts from previous:   
Reply to topic    Gentoo Forums Forum Index Networking & Security All times are GMT
Page 1 of 1

 
Jump to:  
You cannot post new topics in this forum
You cannot reply to topics in this forum
You cannot edit your posts in this forum
You cannot delete your posts in this forum
You cannot vote in polls in this forum