Hi to all, Currently, my server is acting as both a web and mail server. What I''m trying to do is to restrict the amount of relaying mail traffics out from my server while the rest (web, ftp etc ...) still enjoy the full bandwidth. I''m a newbies in this traffic controlling stuffs and hope you can point out the errors in my flags ... Here''s the tc commands I''ve modified from Adv-Routing-HOWTO example:- tc qdisc add dev eth0 root handle 1: cbq bandwidth 10Mbit allot 1514 cell 8 avpkt 1000 mpu 64 tc class add dev eth0 parent 1: classid 1:1 cbq bandwidth 10Mbit rate 10Mbit allot 1514 cell 8 weight 1Mbit prio 8 maxburst 20 avpkt 1000 tc class add dev eth0 parent 1:1 classid 1:2 cbq bandwidth 128Kbit rate 128Kbit allot 1514 cell 8 weight 12Kbit prio 3 maxburst 20 avpkt 1000 split 1:0 bounded tc class add dev eth0 parent 1:1 classid 1:3 cbq bandwidth 10Mbit rate 10Mbit allot 1514 cell 8 weight 1Mbit prio 7 maxburst 20 avpkt 1000 split 1:0 bounded tc filter add dev eth0 parent 1: prio 3 protocol ip u32 tc filter add dev eth0 parent 1: prio 3 u32 match tcp dst 0x0019 0xffff match ip protocol 0x6 0xff flowid 1:2 Does the above sequences make any sense? I believe the problem lies in the last line. I was trying to match all outgoing traffic destined for port 25. However, I tried sending a large attachment (abt. 1.2MB) and it reaches my external mail server using the full bandwidth (took abt. 30secs). So I did a little debugging and change the last line to tc filter add dev eth0 parent 1: prio 3 u32 match ip dst 10.0.0.0/24 flowid 1:2 ( here all traffic going to my internal network get throttled ) I tried retrieving a file via http and true enough, the traffic control works. I can only download the file at the rate of 15.0KB/Sec (according to IE 5). 15 * 8 = 120. So I suppose my 128Kbit bandwidth is working perfectly. So I think the problem lies in this command tc filter add dev eth0 parent 1: prio 3 u32 match tcp dst 0x0019 0xffff match ip protocol 0x6 0xff flowid 1:2 Can someone help me with my filtering rule? I tried all combination but it just doesn''t seem to work. thanks for your attention. cheers! /shaoming