How to make simple traffic control for a specific port using the "tc" command

Question

I am new to Linux and my goal is to create simple traffic control for "eth0" or "lo" using the tc command (or other commands like ifconfig or iptables, but I don't think I need them).

My kernel is 2.6.18-238.el5 GNU / Linux, and I use redhat.

my script:

tc qdisc del dev $DEV root tc qdisc add dev $DEV root handle 1: htb default 10 tc class add dev $DEV parent 1: classid 1:10 htb rate $DNLD tc filter add dev $DEV parent 1: protocol ip u32 match ip dport $input_port 0xffff flowid 1:10 

and $ DNLD is the bandwidth limit, $ DEV is eth0 or lo, and $ input_port is the port I want to limit.

I read many pages on the Internet and realized that it should be written that way, but these lines do not limit a specific port, but all ports.

I tried to use also “sport”, but it also does not work. so I don’t understand what the problem is.

Another weird thing is that the bandwidth limit seems to work, and the reset line also works, and this is the first line: tc qdisc del dev $ DEV root)

but still, the output line after I write this: "RTNETLINK answers: there is no such file or directory" and I do not know why and if it does any damage.

Please let me know if you need any other information. I will be glad if someone can help me. thanks in advance.

Answer 1

I don't know if this is exactly what you are looking for, but it is a script that you can edit and run. I use it to throttle connections and test web applications.

 #!/bin/bash # # tc uses the following units when passed as a parameter. # kbps: Kilobytes per second # mbps: Megabytes per second # kbit: Kilobits per second # mbit: Megabits per second # bps: Bytes per second # Amounts of data can be specified in: # kb or k: Kilobytes # mb or m: Megabytes # mbit: Megabits # kbit: Kilobits # To get the byte figure from bits, divide the number by 8 bit # # # Name of the traffic control command. TC=/sbin/tc # The network interface we're planning on limiting bandwidth. IF=`ip addr | grep 2: | cut -d' ' -f2 | cut -d: -f1` # Latency LAT_1=200ms # Base latency LAT_2=50ms # Plus or minus LAT_3=25% # Based on previous packet % # Dropping packets DROP_1=5% # Base probability DROP_2=25% # Based on previous packet % # Bandwidth #DNLD=33kbps # DOWNLOAD Limit #UPLD=33kbps # UPLOAD Limit DNLD=1Mbps # DOWNLOAD Limit UPLD=1Mbps # UPLOAD Limit # IP address of the machine we are controlling IP=`ip addr | grep "inet " | tail -1 | cut -d' ' -f6 | cut -d/ -f1` # Filter options for limiting the intended interface. U32="$TC filter add dev $IF protocol ip parent 1:0 prio 1 u32" # We'll use Hierarchical Token Bucket (HTB) to shape bandwidth. # For detailed configuration options, please consult Linux man # page. #$TC qdisc add dev $IF root handle 2: netem delay $LAT_1 $LAT_2 $LAT_3 loss $DROP_1 $DROP_2 $TC qdisc add dev $IF root handle 2: netem delay $LAT_1 $LAT_2 $LAT_3 loss $DROP_1 $DROP_2 $TC qdisc add dev $IF parent 2: handle 1: htb default 30 $TC class add dev $IF parent 1: classid 1:1 htb rate $DNLD $TC class add dev $IF parent 1: classid 1:2 htb rate $UPLD $U32 match ip dst $IP/32 flowid 1:1 $U32 match ip src $IP/32 flowid 1:2 # The first line creates the root qdisc, and the next three lines # create three child qdisc that are to be used to shape download # and upload bandwidth. # # The 5th and 6th line creates the filter to match the interface. # The 'dst' IP address is used to limit download speed, and the # 'src' IP address is used to limit upload speed. echo Limit to $DNLD on $IF for $IP