Linux/ngrepについて、ここに記述してください。

https://www.tecmint.com/ngrep-network-packet-analyzer-for-linux/

$ ngrep
The program 'ngrep' is currently not installed. You can install it by typing:
sudo apt install ngrep
tmaeno@u16:~$ sudo apt install ngrep
[sudo] password for tmaeno: 

Reading package lists... Done
Building dependency tree       
Reading state information... Done
The following additional packages will be installed:
  libnet1
The following NEW packages will be installed:
  libnet1 ngrep
0 upgraded, 2 newly installed, 0 to remove and 15 not upgraded.
Need to get 68.1 kB of archives.
After this operation, 260 kB of additional disk space will be used.
Do you want to continue? [Y/n] 
Get:1 http://jp.archive.ubuntu.com/ubuntu xenial/main amd64 libnet1 amd64 1.1.6+dfsg-3 [42.1 kB]
Get:2 http://jp.archive.ubuntu.com/ubuntu xenial/universe amd64 ngrep amd64 1.45.ds2-13 [26.0 kB]
Fetched 68.1 kB in 7s (9,692 B/s)
Selecting previously unselected package libnet1:amd64.
(Reading database ... 239775 files and directories currently installed.)
Preparing to unpack .../libnet1_1.1.6+dfsg-3_amd64.deb ...
Unpacking libnet1:amd64 (1.1.6+dfsg-3) ...
Selecting previously unselected package ngrep.
Preparing to unpack .../ngrep_1.45.ds2-13_amd64.deb ...
Unpacking ngrep (1.45.ds2-13) ...
Processing triggers for man-db (2.7.5-1) ...
Setting up libnet1:amd64 (1.1.6+dfsg-3) ...
Setting up ngrep (1.45.ds2-13) ...
Processing triggers for libc-bin (2.23-0ubuntu10) ...

1. 使用例

$ sudo ngrep port 53