ngrep strives to provide most of GNU grep's common features, applying them to the network layer.
ngrep is a pcap-aware tool that will allow you to specify extended regular or hexadecimal
expressions to match against data payloads of packets. It currently recognizes IPv4/6, TCP,
UDP, ICMPv4/6, IGMP and Raw across Ethernet, PPP, SLIP, FDDI, Token Ring and null interfaces,
and understands BPF filter logic in the same fashion as more common packet sniffing tools,
such as tcpdump and snoop.

Converts/manipulates/extracts data from a Nmap scan output.

nuttcp is a network performance measurement tool intended for use by network
and system managers. Its most basic usage is to determine the raw TCP (or UDP)
network layer throughput by transferring memory buffers from a source system
across an interconnecting network to a destination system, either transferring
data for a specified time interval, or alternatively transferring a specified
number of bytes.

This is the OwnTracks command line interface publisher, a.k.a.
ocli, a small utility which connects to gpsd and publishes position
information in OwnTracks JSON to an MQTT broker in order for
compatible software to process location data.

Omphalos is a tool for visualizing and controlling a local network (though it
will also process pcap savefiles). Captured packets are analyzed to build a
database of hosts and services. Various scans can be performed to elicit
informative packets. Spoofing and redirection at several layers allows flows
to be redirected through the host machine, or silenced. Omphalos is fully IPv6
aware, and makes use of numerous service discovery protocols.

P0f is a tool that utilizes an array of sophisticated, purely passive traffic
fingerprinting mechanisms to identify the players behind any incidental TCP/IP
communications (often as little as a single normal SYN) without interfering in
any way.

A command line tool to run SQL queries directly on PCAP files, the results
can be outputted as JSON (default), formatted/compact CSV and XML.#
It also contain a very simplistic web-server in order to inspect PCAP files
remotely.
PacketQ was previously known as DNS2db but was renamed in 2011 when it was
rebuilt and could handle protocols other than DNS among other things.

Paping (pronounced pah ping) is a computer network administration utility
used to test the reachability of a host on an Internet Protocol (TCP/IP)
network and to measure the time it takes to connect to a specified port.

redfishtool is a commandline tool that implements the client side
of the Redfish RESTful API for Data Center Hardware Management.

Find all open ports fast with RustScan, then automatically
pipe them into Nmap.

Scamper is a program that is able to conduct Internet measurement
tasks to large numbers of IPv4 and IPv6 addresses, in parallel, to
fill a specified packets-per-second rate. Currently, it supports the
well-known ping and traceroute techniques, as well as MDA traceroute,
alias resolution, some parts of tbit, sting, and neighbour discovery.

Scamper can do ICMP-based Path MTU discovery. scamper starts with the
outgoing interface's MTU and discovers the location of Path MTU
bottlenecks. scamper performs a PMTUD search when an ICMP
fragmentation required message is not returned to establish the PMTU
to the next point in the network, followed by a TTL limited search to
infer where the failure appears to occur.

ser2net provides a way for a user to connect from a network connection to a
serial port. It provides all the serial port setup, a configuration file to
configure the ports, a control login for modifying port parameters,
monitoring ports, and controlling ports.

The sethdlc utility is used to set physical interface, clock rate,
used HDLC mode, and can add any required PVCs if using Frame Relay.

https://www.kernel.org/doc/Documentation/networking/generic-hdlc.txt

Simple multicast Server/Client application.
Supports:

* IPv4 AND IPv6
* Multicast Server
* Multicast client
* Source Specific Multicast client

SNMP Simulator is a software that would act like a multitude of real
physical devices from SNMP Manager's point of view. Simulator builds
and uses a database of physical devices' SNMP footprints to respond
like their real counterparts do.

Typical use case for this software starts with recording a snapshot
of SNMP objects of donor agents into text files. Once you have your
snapshots at hand, a simulator script could be run over the snapshots
responding to SNMP queries in the same way as donor SNMP agents did
at the time of recording.

Technically, SNMP Simulator is a multi-context SNMP agent. That means
that it handles multiple sets of managed object all at once.
Each device is simulated within a dedicated SNMP context.

Simple SCEP (Simple Certificate Enrollment Protocol) client with
modifications for engine support & more.

A collection of various tools using ssh
The following tools are included
* ssh-ping: check if host is reachable using ssh_config
* ssh-version: shows version of the SSH server you are connecting to
* ssh-diff: diff a file over SSH
* ssh-facts: get some facts about the remote system
* ssh-hostkeys: prints server host keys in several formats
* ssh-keyinfo: prints keys in several formats
* ssh-certinfo: shows validity and information of SSH certificates

SSHamble simulates potential attack scenarios, including
unauthorized remote access due to unexpected state transitions,
remote command execution in post-session login implementations
and information leakage through unlimited high-speed authentication
requests.

The SSHamble interactive shell provides raw access to SSH requests in
the post-session (but pre-execution) environment, allowing for simple
esting of environment controls, signal processing, port forwarding,
and more.

Utility to test the performance of interactive ssh sessions or scp file
transfers. It uses ssh to log into a remote system, then runs two tests: the
first test sends one character at a time, waiting for each character to be
returned while it records the latency time for each. The second test sends a
dummy file over scp to /dev/null on the remote system.

TCPing will send TCP probes to an IP address or a hostname specified
by you and prints the result.
It works with both IPv4 and IPv6.

TCPING uses different TCP sequence numbering for successful and
unsuccessful probes, so that when you look at the results and spot
a failed probe, understanding the total packet drops to that point
would be illustrative enough.

* Monitor your network connection.
* Determine packet loss.
* Analyze the network's latency.
* Show min/avg/max probes latency.
* Use the -r flag to retry hostname resolution after a predetermined
number of ping failures. If you want to test your DNS load
balancing or Global Server Load Balancer (GSLB), you should
utilize this option..
* Print connection statistics on Enter key press.
* Display the longest encountered downtime and uptime duration and
time.
* Monitor and audit your peers network.
* Calculate the total uptime/downtime when conducting a maintenance.
* An alternative to ping in environments that ICMP is blocked.

A terminal UI for tshark, inspired by Wireshark.

testssl.sh is a free command line tool which checks a server's service on
any port for the support of TLS/SSL ciphers, protocols as well as some
cryptographic flaws.

A CLI tool that parses and manipulates URLs, designed to help
shell script authors everywhere.