Delaying network traffic to a specific IP

delay.sh

#!/bin/bash

interface=lo
ip=10.0.0.1
delay=100ms

tc qdisc add dev $interface root handle 1: prio
tc filter add dev $interface parent 1:0 protocol ip prio 1 u32 match ip dst $ip flowid 2:1
tc qdisc add dev $interface parent 1:1 handle 2: netem delay $delay

Nice tool to visualize tc rules: http://ze.phyr.us/visualizing-linux-traffic-control-setup/

thx for the snippet!

small question: line 8, shouldn't be the last qdisc-id 1:1? because in line 9 you are using 1:1 to add the delay.

this is not working when using "ip src" instead

HOWTO verify network delay between two servers

PORT=12345

# Server side
nc -vl $PORT

# Client side
SERVER_IP="..."
time nc -vz $SERVER_IP $PORT

how to reset after testing??

how to reset after testing??

Use tc qdisc del dev $interface root
for resetting after testing.

how can we extend it two servers, i.e., different delays for different IPs?

I made a python wrapper for this https://github.com/fledge-iot/fledge/blob/3a92d1786fc58dec499f335b79106840d0c7c8bb/tests/system/python/packages/network_impairment.py#L110

call it two times giving suitable IPs for each of the servers. Hope that helps

thanks @deepanshu-yadav I'll go through the Python file. A quick qstn, do I need to change parentid/flow id? I see following error
Error: Exclusivity flag on, cannot modify. when I tried following code

delay.sh
tc qdisc add dev $interface root handle 1: prio
tc filter add dev $interface parent 1:0 protocol ip prio 1 u32 match ip dst $ip1 flowid 2:1
tc qdisc add dev $interface parent 1:1 handle 2: netem delay $delay1
tc filter add dev $interface parent 1:0 protocol ip prio 1 u32 match ip dst $ip2 flowid 2:1
tc qdisc add dev $interface parent 1:1 handle 2: netem delay $delay2

You need to divide your traffic into three parts packets for ip1 , packets for ip2 and packets for ip2.

This is possible please go through all the links I have given in the code (start).

There is a lot to learn and your problem is not a simple copy paste from stack overflow .

It seems all solutions are qdisc-prio-based, but qdisc-prio has a limit of 16 priorities, so one can't use it for 17 or more routes

This will somehow affects my SSH connect to the remote server where those command runs while successfully delaying certain IP flow. Don't know how to fix it. TAT