Wireshark

Wireshark is a free and open-source packet analyzer. It is used for network troubleshooting, analysis, software and communications protocol development, and education. Originally named Ethereal, in May 2006 the project was renamed Wireshark due to trademark issues.

Installation

The wireshark package has been split into the CLI version and GTK frontend, which depends on the CLI.

CLI version can be installed with the package wireshark-cli, available in the official repositories.

GTK frontend can be installed with the package wireshark-gtk, available in the official repositories.

Capturing as normal user

Running Wireshark as root is insecure.

Arch Linux uses method from Wireshark wiki to separate privileges. When wireshark-gtk is installed, install script sets /usr/bin/dumpcap capabilities.

$ getcap /usr/bin/dumpcap 
/usr/bin/dumpcap = cap_net_admin,cap_net_raw+eip

/usr/bin/dumpcap is the only process that has privileges to capture packets. /usr/bin/dumpcap can only be run by root and members of the wireshark group.

To use wireshark as a normal user, add user to the wireshark group:

# gpasswd -a "username" wireshark

Another way is to use sudo to temporarily change group to wireshark. The following line allows all users in the wheel group to run programs with GID set to wireshark GID:

%wheel ALL=(:wireshark) /usr/bin/wireshark, /usr/bin/tshark

Then run wireshark with

$ sudo -g wireshark wireshark

A few capturing techniques

There are a number of different ways to capture exactly what you are looking for in Wireshark, by applying filters.

Note: To learn the filter syntax, see man pcap-filter(7).

Filtering TCP packets

If you want to see all the current TCP packets, type tcp into the "Filter" bar.

Filtering UDP packets

If you want to see all the current UDP packets, type udp into the "Filter" bar.

Filter packets to a specific IP Address

• If you would like to see all the traffic going to a specific address, enter ip.dst == 1.2.3.4, replacing 1.2.3.4 with the IP address the outgoing traffic is being sent to.

• If you would like to see all the incoming traffic for a specific address, enter ip.src == 1.2.3.4, replacing 1.2.3.4 with the IP address the incoming traffic is being sent to.