Networking tutorials and examples

DIG quick start tutorial for DNS Lookup

Dig (Domain information groper) can be used to do DNS lookup on Linux, Mac or windows machine. It will connect a DNS server (default or read more

Dig – list all dns records

To list all DNS records of a domain name use the following dig command (after replacing with desired domain) $ dig any ;; read more

How to view wifi connection speed on Mac

When you setup your wifi router and you mac is connected to it, you may want to know what is wifi link speed (the bandwidth read more

Linux iptables – Nat port forwarding using PREROUTING

One can use iptables to forward a specific port to another port using NAT PREROUTING chain. This can be used to make a server available read more

Linux iptables and ip6tables examples

Linux iptables is a user-space application program that allows a system administrator to configure the tables provided by the Linux kernel firewall (implemented as different read more

Ngrep – quick start guide

Ngrep is similar to tcpdump with ability to look for regex search in packets playload and show matching packets to screen. This can be very read more

Use netcat (nc) to check if a remote port is reachable

Netcat (nc) can be use to check if a remote port is reachable and client can connect to it. The following commands were tried on read more

Use netcat (nc) to listen on tcp or udp port

Netcat (nc) can be use as a mini server which can listen to either tcp or udp port on Mac or Linux. nc – listen read more

how to use netcat (nc) to test HTTP url redirection

Netcat (nc) is pretty powerful command line tool on Linux & Mac and can be used to send data on network. It can be quickly read more

How to add more DNS servers to Wi-Fi interface on Mac

When you are using WiFi or wired network using home broadband or mobile hotspot, you are assigned a default DNS server. It sometimes may be read more

How to locally override website domain (or hostname) to IP mapping

When we browse a web site, the browser first do a DNS lookup to find the IP address of the domain name. We can override read more

How to use nc (netcat) to print headers sent by a browser

Unix utility nc (netcat) is a pretty handy utility for many network tasks. One such use is to see what headers are being sent by read more