I use the following script for my Linksys WRT54GS Wireless router running OpenWRT White Russian -RC4 to setup a QoS firewall that uses Hierarchical Token Bucket (HTB) and Stochastic Fair Queueing (SFQ) to classify the traffic in three cathegories:

1. Interactive, high priority traffic:
   This class is used for DNS traffic and SSH traffic.
2. Interactive, normal priority traffic:
   This class is used for HTTP and HTTP/S traffic.
3. Low priority traffic:
   This class is used for traffic which doesn’t fit any of the previous classes.

Each class is also subclassed with Stochastic Fair Queueing (SFQ) to distribute traffic utilization among the same class evenly.

To make the script run every time the router is powered up, save the script as /etc/init.d/S41qos and turn the executable bit on it.

#!/bin/ash

# Executables
GREP=/bin/grep
INSMOD=/sbin/insmod
TC=/usr/sbin/tc
DEV=vlan1

# Load kernel modules
$GREP -q ^sch_htb /proc/modules || $INSMOD /lib/modules/`uname -r`/sch_htb.o
$GREP -q ^sch_sfq /proc/modules || $INSMOD /lib/modules/`uname -r`/sch_sfq.o
$GREP -q ^cls_u32 /proc/modules || $INSMOD /lib/modules/`uname -r`/cls_u32.o

# Hierarchical Token Bucket (HTB)
$TC qdisc add dev $DEV root handle 1: htb default 30
$TC class add dev $DEV parent 1: classid 1:1 htb rate 1mbit burst 20k cburst 20k

# HTB Classes
$TC class add dev $DEV parent 1:1 classid 1:10 htb 
   rate 768kbit ceil 1mbit burst 15k cburst 15k
$TC class add dev $DEV parent 1:1 classid 1:20 htb 
   rate 256kbit ceil 1mbit burst 20k cburst 20k
$TC class add dev $DEV parent 1:1 classid 1:30 htb 
   rate 128kbit ceil 512kbit burst 5k cburst 5k

$TC qdisc add dev $DEV parent 1:10 handle 10: sfq perturb 10
$TC qdisc add dev $DEV parent 1:20 handle 20: sfq perturb 10
$TC qdisc add dev $DEV parent 1:30 handle 30: sfq perturb 10

# Filters
$TC filter add dev $DEV protocol ip parent 1:0 prio 1 
   u32 match ip dport 53 0xffff flowid 1:10
$TC filter add dev $DEV protocol ip parent 1:0 prio 2 
   u32 match ip dport 22 0xffff flowid 1:10
$TC filter add dev $DEV protocol ip parent 1:0 prio 10 
   u32 match ip dport 80 0xffff flowid 1:20
$TC filter add dev $DEV protocol ip parent 1:0 prio 10 
   u32 match ip dport 443 0xffff flowid 1:20