Re: limiting download speed

["Nikita V. Youshchenko" <yoush@cs.msu.su>]

> Hello.
> 
> My home computer (running Debian sid, kernel 2.4) is connected to a LAN
> and runs Apache to serve web pages and files to other computers in the
> LAN.
> 
> Recently admins of the LAN told me to limit total download speed from my
> computer over http. Than means, if one person is downloading from my
> computer, he should get at most N kbps, but if e.g. 3 people are
> downloading from my computer, each one should get at most N/3 kbps.
> 
> What is the correct way to do that? Although I am a unix admin, I have
> never solved this before. Seems that I need to configure iproute? Or there
> is a better way? I want to limit only outgoing HTTP traffic; if at the
> same time I am uploading a file to some other computer, there should be no
> local speed limit.
> 
> Could someone please help me to do what LAN admins want, or point to
> appropriate documentation?

Well, here is how this may be done using iproute:

dev="$1"
cmd="$2"

if [ $# -ne 2 -o "`echo $dev | cut -c1-3`" != "eth" -o \
     \( "$cmd" != "on" -a "$cmd" != "off" \) ]; then
  echo "usage bandwidth-limit device [on|off]" >&2
  exit 1
fi

if [ $cmd = on ]; then

  tc qdisc add dev "$dev" root handle 1:0 cbq bandwidth 10Mbit avpkt 1000

  tc class add dev "$dev" parent 1:0 classid 1:1 cbq \
    bandwidth 10Mbit rate 10MBit prio 1 cell 8 maxburst 20 avpkt 1000 allot
1514
  tc class add dev "$dev" parent 1:0 classid 1:2 cbq bounded \
    bandwidth 10Mbit rate 64kbps prio 2 cell 8 maxburst 20 avpkt 1000 allot
1514

  tc qdisc add dev "$dev" parent 1:1 handle 11: sfq
  tc qdisc add dev "$dev" parent 1:2 handle 12: sfq

  tc filter add dev "$dev" parent 1:0 prio 1 \
    protocol ip u32 match ip sport 80 0xffff flowid 1:2

elif [ $cmd = off ]; then

  tc qdisc del dev "$dev" root handle 1:0 cbq bandwidth 10Mbit avpkt 1000

fi
n