Linux limit TX(output transmit) of some Port on the specified Interface. Use tc and iptables.

limit_tx.sh

    #!/bin/bash

    # 
    # limite net output rate
    #
    # 2014.09.25 
    # with kernel 2.6, netem was added to kernel,
    # so it is easier to use it with tc instead of the following way.

    # if su
    if [[ $EUID -ne 0 ]]; then
        echo ""
        echo "You must be a root user" 2>&1
        echo ""
        exit 1
    fi #[[ $EUID -ne 0 ]]; 

    # for help
    if [ $# -lt 1 ] || [ "$1" = "-h" ]; then
        echo "Limit TX(output transmit) of some Port on the specified Interface."
        echo "By Honghe @ Ruijie."
        echo ""
        echo "For help:"
        echo "Usage:    $0 -h"
        echo " "
        echo "Set the speed of Port in a Interface:"
        echo "Usage:    $0 'rate KB/s' 'interface' 'port'"
        echo "Example:  $0  5    eth0    8000"
        echo " "
        echo "Release speed limit:"
        echo "Usage:    $0  -r  'interface'"
        echo "Example:  $0  -r  eth0"
        echo " "
        echo "Show stat:"
        echo "Usage:    $0  -s  'interface'"  
        echo "Example:  $0  -s  eth0"  
        echo " "
        exit 0

    elif [ $# -lt 3 ]; then
        # show status.
        if [[ "$1" = "-s" ]]; then
            LIMIT_DEV="$2"
            echo ""
            tc -s qdisc ls dev ${LIMIT_DEV}
            echo ""
            iptables -t mangle --list
        elif [[ "$1" = "-r" ]]; then
            # release.
            LIMIT_DEV="$2"
            iptables -t mangle -F
            tc qdisc del dev ${LIMIT_DEV} root
            echo " "
            echo "Speed limit released."
            echo " "
        else
            echo ""
            echo "Syntax wrong, use -h for help."
            echo ""
        fi #[[ "$1" = "-s" ]]

    else
    # set limit

    #RATE Kilobytes per second
    # LIMIT_RATE=1
    # LIMIT_PORT=8000
    # LIMIT_DEV="eth0"
    LIMIT_RATE=$1
    LIMIT_DEV="$2"
    LIMIT_PORT=$3

    # delete existing rule
    tc qdisc del dev ${LIMIT_DEV} root > /dev/null  2>&1
    # Turn on queuing discipline, enter:
    # Here, not use the `defatult 10` by cyberciti as referenced on the end of this shell.
    # /sbin/tc qdisc add dev eth1 root handle 1:0 htb default 10
    # 
    tc qdisc add dev ${LIMIT_DEV} root handle 1:0 htb 

    # Define a class with limitations i.e. set the allowed bandwidth to 512 Kilobytes and burst bandwidth to 640 Kilobytes for port 80:
    tc class add dev ${LIMIT_DEV} parent 1:0 classid 1:10 htb rate ${LIMIT_RATE}kbps ceil ${LIMIT_RATE}kbps prio 0

    # Finally, assign it to appropriate qdisc:
    tc filter add dev ${LIMIT_DEV} parent 1:0 prio 0 protocol ip handle 10 fw flowid 1:10

    # Please note that port 80 is NOT defined anywhere in above class. You will use iptables mangle rule as follows:
    iptables -t mangle -F
    iptables -A OUTPUT -t mangle -p tcp --sport ${LIMIT_PORT} -j MARK --set-mark 10 

    # print 
    echo " "
    echo "Set speed limit: interface ${LIMIT_DEV} port ${LIMIT_PORT} as ${LIMIT_RATE} KB/s"
    echo " "

    fi #[ $# -lt 1 ] || [ "$1" = "-h" ]; 

    #
    # Reference:
    # http://www.cyberciti.biz/faq/linux-traffic-shaping-using-tc-to-control-http-traffic/
    #