Posts Tagged kernel

Traffic shaping under Linux with tc and iptables

My aim was to make traffic shaping in our office. Internet router and development server is the same computer. Local network which consist of workstations has to have 300 kbit internet access and also full 1Gbit access to development server. Development server has to have unlimited access to internet. So we have to shape only the traffic which goes from local network to internet. My local network interface is eth1, internet interface is eth0. Local network is 192.168.0.0/255.255.255.0 and development server’s IP is 192.168.0.1.
I have read some documentation on tc and iptables and wrote this scripts.

shaper.sh

#!/bin/sh
# Delete root qdisc from eth1 in case that we execute this script for the second time
tc qdisc del dev eth1 root
# Create root qdisc
tc qdisc add dev eth1 root handle 1:0 htb default 2
# Create main class with 1 Gbit traffic
tc class add dev eth1 parent 1:0 classid 1:1 htb rate 1024mbit ceil 1024mbit
# Create class for local network with 300 Kbit traffic
tc class add dev eth1 parent 1:1 classid 1:2 htb rate 300kbit ceil 300kbit
# Create class for development server again with 1 Gbit
tc class add dev eth1 parent 1:1 classid 1:3 htb rate 1024mbit ceil 1024mbit
# Adding qdiscs to our tree leaves
tc qdisc add dev eth1 parent 1:2 sfq
tc qdisc add dev eth1 parent 1:3 sfq
# Route packets marked with 0x7 to 1:2 qdisc which is for local network
tc filter add dev eth1 parent 1:0 protocol ip prio 1 handle 7 fw flowid 1:2
# Route packets marked with 0x8 to 1:3 qdisc which is for development server
tc filter add dev eth1 parent 1:0 protocol ip prio 1 handle 8 fw flowid 1:3

And finaly we have to configure iptables to mark packets 0×7 or 0×8 acording to its source and destination

iptables_config.sh

#!/bin/sh
# Create three chains for routing
iptables -t mangle -N traffic_office
iptables -t mangle -N traffic_office_to_server
iptables -t mangle -N traffic_server
# Mark traffic from local network 0x7
iptables -t mangle -A traffic_office -j MARK --set-mark 0x7
# Mark traffic from local network to dev server 0x8
iptables -t mangle -A traffic_office_to_server -j MARK --set-mark 0x8
# Mark traffic from internet to dev server 0x8
iptables -t mangle -A traffic_server -j MARK --set-mark 0x8
# Send traffic to chain traffic_server which comes from server and not going to local network
iptables -t mangle -A POSTROUTING -s 192.168.0.1 -d ! 192.168.0.0/255.255.255.0 -j traffic_server
# Send traffic to chain traffic_server which comes from somewhere, not from local network and goes to dev server
iptables -t mangle -A POSTROUTING -s ! 192.168.0.0/255.255.255.0 -d 192.168.0.1 -j traffic_server
# Send traffic to chain traffic_office which comes not from dev server and goes to local network
iptables -t mangle -A POSTROUTING -s ! 192.168.0.1 -d 192.168.0.0/255.255.255.0 -j traffic_office
# Send traffic to chain traffic_office which comes local network and goes not to dev server
iptables -t mangle -A POSTROUTING -s 192.168.0.0/255.255.255.0 -d ! 192.168.0.1 -j traffic_office
# Send traffic to chain traffic_office_to_server which comes dev server and goes to local network
iptables -t mangle -A POSTROUTING -s 192.168.0.1 -d 192.168.0.0/255.255.255.0 -j traffic_office_to_server
# Send traffic to chain traffic_office_to_server which comes local network and goes to dev server
iptables -t mangle -A POSTROUTING -s 192.168.0.0/255.255.255.0 -d 192.168.0.1 -j traffic_office_to_server

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