tcpdump is a data-network packet analyzer computer program that runs under a command line interface. It allows the user to display TCP/IP and other packets being transmitted or received over a network to which the computer is attached. Distributed under the BSD license, tcpdump is free software.
In computer networking, ARP spoofing, ARP cache poisoning, or ARP poison routing, is a technique by which an attacker sends (spoofed) Address Resolution Protocol (ARP) messages onto a local area network. Generally, the aim is to associate the attacker's MAC address with the IP address of another host, such as the default gateway, causing any traffic meant for that IP address to be sent to the attacker instead.
dSniff is a set of password sniffing and network traffic analysis tools written by security researcher and startup founder Dug Song to parse different application protocols and extract relevant information. dsniff, filesnarf, mailsnarf, msgsnarf, urlsnarf, and webspy passively monitor a network for interesting data. arpspoof, dnsspoof, and macof facilitate the interception of network traffic normally unavailable to an attacker. sshmitm and webmitm implement active man-in-the-middle attacks against redirected SSH and HTTPS sessions by exploiting weak bindings in ad-hoc PKI.
"Zero-copy" describes computer operations in which the CPU does not perform the task of copying data from one memory area to another or in which unnecessary data copies are avoided. This is frequently used to save CPU cycles and memory bandwidth in many time consuming tasks, such as when transmitting a file at high speed over a network, etc., thus improving the performance of programs (processes) executed by a computer.
In the field of computer network administration, pcap is an application programming interface (API) for capturing network traffic. While the name is an abbreviation of packet capture, that is not the API's proper name. Unix-like systems implement pcap in the libpcap library; for Windows, there is a port of libpcap named WinPcap that is no longer supported or developed, and a port named Npcap for Windows 7 and later that is still supported.
Packet crafting is a technique that allows network administrators to probe firewall rule-sets and find entry points into a targeted system or network. This is done by manually generating packets to test network devices and behaviour, instead of using existing network traffic. Testing may target the firewall, IDS, TCP/IP stack, router or any other component of the network. Packets are usually created by using a packet generator or packet analyzer which allows for specific options and flags to be set on the created packets. The act of packet crafting can be broken into four stages: Packet Assembly, Packet Editing, Packet Play and Packet Decoding. Tools exist for each of the stages - some tools are focused only on one stage while others such as Ostinato try to encompass all stages.
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, the project was renamed Wireshark in May 2006 due to trademark issues.
The Berkeley Packet Filter is a network tap and packet filter which permits computer network packets to be captured and filtered at the operating system level. It provides a raw interface to data link layers, permitting raw link-layer packets to be sent and received, and allows a userspace process to supply a filter program that specifies which packets it wants to receive. For example, a tcpdump process may want to receive only packets that initiate a TCP connection. BPF returns only packets that pass the filter that the process supplies. This avoids copying unwanted packets from the operating system kernel to the process, greatly improving performance. The filter program is in the form of instructions for a virtual machine, which are interpreted, or compiled into machine code by a just-in-time (JIT) mechanism and executed, in the kernel.
Packet injection in computer networking, is the process of interfering with an established network connection by means of constructing packets to appear as if they are part of the normal communication stream. The packet injection process allows an unknown third party to disrupt or intercept packets from the consenting parties that are communicating, which can lead to degradation or blockage of users' ability to utilize certain network services or protocols. Packet injection is commonly used in man-in-the-middle attacks and denial-of-service attacks.
Mausezahn is a fast network traffic generator written in C which allows the user to craft nearly every possible and "impossible" packet. Since version 0.31 Mausezahn is open source in terms of the GPLv2. Herbert Haas, the original developer of Mausezahn, died on 25 June 2011. The project has been incorporated into the netsniff-ng toolkit, and continues to be developed there.
EtherApe is a packet sniffer/network traffic monitoring tool, developed for Unix. EtherApe is free, open source software developed under the GNU General Public License.
Iftop is a free software command-line system monitor tool developed by Paul Warren. It produces a real-time stream of incoming and outgoing network communications from the operating system iftop is running within. By default, the connections are ordered by bandwidth usage, with only the largest ("top") bandwidth consumers shown. It is analogous to top, but instead of system-wide resource monitoring, it focuses on displaying just network usage. Iftop is typically used for monitoring bandwidth consumption, and while investigating unknown consumers of available network bandwidth.
Bit-Twist is a libpcap-based packet generator and packet capture file modifier and replayer. It complements tcpdump, a packet capturing tool also built upon the packet capturing engine libpcap. Bit-Twist allows you to regenerate packets from one or more pcap files. It also comes with a comprehensive pcap file editor to allow advance manipulation of packet information, e.g. fields in Ethernet, ARP, IP, ICMP, TCP, and UDP headers, prior to regenerating the packets onto the network.
ngrep is a network packet analyzer written by Jordan Ritter. It has a command-line interface, and relies upon the pcap library and the GNU regex library.
Justniffer is a TCP packet sniffer. It can log network traffic in a 'standard' or in a customized way. It can also log response times, useful for tracking network services performances . The output format of the traffic can be easily customized. An example written in Python stores the transferred contents in an output directory separated by domains. This means that the transferred files like html, css, javascript, images, sounds, etc. can be saved to a directory.
Xplico is a network forensics analysis tool (NFAT), which is a software that reconstructs the contents of acquisitions performed with a packet sniffer.
A network scheduler, also called packet scheduler, queueing discipline (qdisc) or queueing algorithm, is an arbiter on a node in a packet switching communication network. It manages the sequence of network packets in the transmit and receive queues of the protocol stack and network interface controller. There are several network schedulers available for the different operating systems, that implement many of the existing network scheduling algorithms.
XDP is an eBPF-based high-performance data path used to send and receive network packets at high rates by bypassing most of the operating system networking stack. It is merged in the Linux kernel since version 4.8. This implementation is licensed under GPL. Large technology firms including Amazon, Google and Intel support its development. Microsoft released their free and open source implementation XDP for Windows in May 2022. It is licensed under MIT License.
PCAP-over-IP is a method for transmitting captured network traffic through a TCP connection. The captured network traffic is transferred over TCP as a PCAP file in order to preserve relevant metadata about the packets, such as timestamps.
Cilium is a cloud native technology for networking, observability, and security. It is based on the kernel technology eBPF, originally for better networking performance, and now leverages many additional features for different use cases. The core networking component has evolved from only providing a flat Layer 3 network for containers to including advanced networking features, like BGP and Service mesh, within a Kubernetes cluster, across multiple clusters, and connecting with the world outside Kubernetes. Hubble was created as the network observability component and Tetragon was later added for security observability and runtime enforcement. Cilium runs on Linux and is one of the first eBPF applications being ported to Microsoft Windows through the eBPF on Windows project.
