Show open ports on Mac
If you want to know which ports are open on your Mac, you can use built-in tools in terminal: lsof -i -P | grep -i "listen" This gives you a…
Posts related to TCP/IP
Use netcat instead of telnet
Network engineers often use telnet to establish a connection to a service on a remote server. Apple dropped the telnet and ftp client in macOS High Sierra. First I was…
Hide your version of BIND
To hide your version of bind, enter the following value to your named.conf version "[NONE]"; in the option section: options { directory "/var/lib/bind"; version "[NONE]"; }; Check the value with…
Subnet Masks
A subnetwork, or subnet, is a logically visible, distinctly addressed part of a single Internet Protocol network. The process of subnetting is the division of a computer network into groups of computers that have a common,…
pcap filter
tcpdump and ngrep are both based on libpcap. Therefore both use the same filter expressions. Here is the manual page of the ⇒pcap filter expression. These filter expressions are also…
Network grep “ngrep” on macOS
Sometimes it is very practical to use grep, to find a specific regular expression in some files. It would also be very practical to have the grep functionality on the…