Author: Albert

How to measure maximum available network speed of your Linux server?

You can use iperf that use client and server scenario to test network speed between two Linux based servers. The tool iperf is available in EPEL free repository else you can download from

The following iperf command will send a buffer size enough to test network speed for 120 seconds

iperf3 -i 5 -t 120 -c <hostname or ip address of server>

On the server side, start iperf with iperf3 -i 5 -s

iperf server listens on TCP port 5201. Allow port 5201 in server firewall to allow server-client connection. If you want to change server listening port use -p option on command line.

Other alternative tools to iperf is ttcp, nc, and netcat.

Why do Linux Kernel log “martian source” in log file /var/log/messages?

Mention of martian source in file /var/log/messages indicates a packet received on the active network interface eth0 whose source or destination IP address is not correct. An example of this scenario is source network IP address is already configured on current system throwing martian source in log files. All this indicate a configuration error in your system that you need to investigate.

The kernel parameter net.ipv4.conf.all.log_martians controls log entry in /var/log/messages. This is executed when the kernel receives a network packet with an incorrect source and/or destination IPv4 address.

To change behavior, set parameter value in /etc/sysctl.conf with net.ipv4.conf.all.log_martians = 1