A packet analyzer, also known as packet sniffer, protocol analyzer, or network analyzer, is a

computer program A computer program is a sequence or set of instructions in a programming language for a computer to execute. Computer programs are one component of software, which also includes documentation and other intangible components. A computer progra ...

or computer hardware such as a packet capture appliance, that can intercept and log traffic that passes over a

computer network A computer network is a set of computers sharing resources located on or provided by network nodes. The computers use common communication protocols over digital interconnections to communicate with each other. These interconnections ar ...

or part of a network. Packet capture is the process of intercepting and logging traffic. As

data stream In connection-oriented communication, a data stream is the transmission of a sequence of digitally encoded coherent signals to convey information. Typically, the transmitted symbols are grouped into a series of packets. Data streaming has ...

s flow across the network, the analyzer captures each packet and, if needed, decodes the packet's raw data, showing the values of various fields in the packet, and analyzes its content according to the appropriate RFC or other specifications. A packet analyzer used for intercepting traffic on wireless networks is known as a wireless analyzer or WiFi analyzer. While a packet analyzer can also be referred to as a network analyzer or protocol analyzer these terms can also have other meanings. Protocol analyzer can technically be a broader, more general class that includes packet analyzers/sniffers. However, the terms are frequently used interchangeably.

Capabilities

On wired

shared-medium network In telecommunication, a shared medium is a medium or channel of information transfer that serves more than one user at the same time. In order for most channels to function correctly, no more than one user can be transmitting at a time, so a cha ...

s, such as

Ethernet Ethernet () is a family of wired computer networking technologies commonly used in local area networks (LAN), metropolitan area networks (MAN) and wide area networks (WAN). It was commercially introduced in 1980 and first standardized in ...

Token Ring Token Ring network IBM hermaphroditic connector with locking clip. Screen contacts are prominently visible, gold-plated signal contacts less so. Token Ring is a computer networking technology used to build local area networks. It was introduc ...

, and

FDDI Fiber Distributed Data Interface (FDDI) is a standard for data transmission in a local area network. It uses optical fiber as its standard underlying physical medium, although it was also later specified to use copper cable, in which case i ...

, depending on the network structure ( hub or

switch In electrical engineering, a switch is an electrical component that can disconnect or connect the conducting path in an electrical circuit, interrupting the electric current or diverting it from one conductor to another. The most common type ...

), it may be possible to capture all traffic on the network from a single machine. On modern networks, traffic can be captured using a network switch using port mirroring, which mirrors all packets that pass through designated ports of the switch to another port, if the switch supports port mirroring. A network tap is an even more reliable solution than to use a monitoring port since taps are less likely to drop packets during high traffic load. On

wireless LAN A wireless LAN (WLAN) is a wireless computer network that links two or more devices using wireless communication to form a local area network (LAN) within a limited area such as a home, school, computer laboratory, campus, or office building ...

s, traffic can be captured on one channel at a time, or by using multiple adapters, on several channels simultaneously. On wired broadcast and wireless LANs, to capture

unicast Unicast is data transmission from a single sender (red) to a single receiver (green). Other devices on the network (yellow) do not participate in the communication. In computer networking, unicast is a one-to-one transmission from one point in ...

traffic between other machines, the

network adapter A network interface controller (NIC, also known as a network interface card, network adapter, LAN adapter or physical network interface, and by similar terms) is a computer hardware component that connects a computer to a computer network. E ...

capturing the traffic must be in

promiscuous mode In computer networking, promiscuous mode is a mode for a wired network interface controller (NIC) or wireless network interface controller (WNIC) that causes the controller to pass all traffic it receives to the central processing unit (CPU) rat ...

. On wireless LANs, even if the adapter is in promiscuous mode, packets not for the service set the adapter is configured for are usually ignored. To see those packets, the adapter must be in

monitor mode Monitor or monitor may refer to: Places * Monitor, Alberta * Monitor, Indiana, town in the United States * Monitor, Kentucky * Monitor, Oregon, unincorporated community in the United States * Monitor, Washington * Monitor, Logan County, We ...

. No special provisions are required to capture

multicast In computer networking, multicast is group communication where data transmission is addressed to a group of destination computers simultaneously. Multicast can be one-to-many or many-to-many distribution. Multicast should not be confused wit ...

traffic to a multicast group the packet analyzer is already monitoring, or

broadcast Broadcasting is the distribution (business), distribution of sound, audio or video content to a dispersed audience via any electronic medium (communication), mass communications medium, but typically one using the electromagnetic spectrum (radio ...

traffic. When traffic is captured, either the entire contents of packets or just the headers are recorded. Recording just headers reduces storage requirements, and avoids some privacy legal issues, yet often provides sufficient information to diagnose problems. Captured information is decoded from raw digital form into a

human-readable format A human-readable medium or human-readable format is any encoding of data or information that can be naturally read by humans. In computing, ''human-readable'' data is often encoded as ASCII or Unicode text, rather than as binary data. In most ...

that lets engineers review exchanged information. Protocol analyzers vary in their abilities to display and analyze data. Some protocol analyzers can also generate traffic. These can act as protocol testers. Such testers generate protocol-correct traffic for functional testing, and may also have the ability to deliberately introduce errors to test the device under test's ability to handle errors. Protocol analyzers can also be hardware-based, either in probe format or, as is increasingly common, combined with a disk array. These devices record packets or packet headers to a disk array.

Uses

Packet analyzers can: * Analyze network problems * Detect

network intrusion A data breach is a security violation, in which sensitive, protected or confidential data is copied, transmitted, viewed, stolen or used by an individual unauthorized to do so. Other terms are unintentional information disclosure, data leak, info ...

attempts * Detect network misuse by internal and external users * Documenting regulatory compliance through logging all perimeter and endpoint traffic * Gain information for effecting a network intrusion * Identify data collection and sharing of software such as operating systems (for strengthening

privacy Privacy (, ) is the ability of an individual or group to seclude themselves or information about themselves, and thereby express themselves selectively. The domain of privacy partially overlaps with security, which can include the concepts of a ...

, control and security) * Aid in gathering information to isolate exploited systems * Monitor WAN bandwidth utilization * Monitor network usage (including internal and external users and systems) * Monitor data in transit * Monitor WAN and endpoint security status * Gather and report network statistics * Identify suspect content in network traffic * Troubleshoot performance problems by monitoring network data from an application * Serve as the primary data source for day-to-day network monitoring and management * Spy on other network users and collect sensitive information such as login details or users cookies (depending on any content

encryption In cryptography, encryption is the process of encoding information. This process converts the original representation of the information, known as plaintext, into an alternative form known as ciphertext. Ideally, only authorized parties can dec ...

methods that may be in use) *

Reverse engineer Reverse engineering (also known as backwards engineering or back engineering) is a process or method through which one attempts to understand through deductive reasoning how a previously made device, process, system, or piece of software accompli ...

proprietary protocol In telecommunications, a proprietary protocol is a communications protocol owned by a single organization or individual. Intellectual property rights and enforcement Ownership by a single organization gives the owner the ability to place restricti ...

s used over the network * Debug client/server communications * Debug network protocol implementations * Verify adds, moves, and changes * Verify internal control system effectiveness ( firewalls, access control, Web filter, spam filter, proxy) Packet capture can be used to fulfill a warrant from a law enforcement agency to

wiretap Telephone tapping (also wire tapping or wiretapping in American English) is the monitoring of telephone and Internet-based conversations by a third party, often by covert means. The wire tap received its name because, historically, the monitorin ...

all network traffic generated by an individual.

Internet service provider An Internet service provider (ISP) is an organization that provides services for accessing, using, or participating in the Internet. ISPs can be organized in various forms, such as commercial, community-owned, non-profit, or otherwise privatel ...

s and

VoIP Voice over Internet Protocol (VoIP), also called IP telephony, is a method and group of technologies for the delivery of voice communications and multimedia sessions over Internet Protocol (IP) networks, such as the Internet. The terms Interne ...

providers in the United States must comply with

Communications Assistance for Law Enforcement Act The Communications Assistance for Law Enforcement Act (CALEA), also known as the "Digital Telephony Act," is a United States wiretapping law passed in 1994, during the presidency of Bill Clinton (Pub. L. No. 103-414, 108 Stat. 4279, codified at 47 ...

regulations. Using packet capture and storage, telecommunications carriers can provide the legally required secure and separate access to targeted network traffic and can use the same device for internal security purposes. Collecting data from a carrier system without a warrant is illegal due to laws about interception. By using

end-to-end encryption End-to-end encryption (E2EE) is a system of communication where only the communicating users can read the messages. In principle, it prevents potential eavesdroppers – including telecom providers, Internet providers, malicious actors, and eve ...

, communications can be kept confidential from telecommunication carriers and legal authorities.

Notable packet analyzers

* Allegro Network Multimeter *

Capsa Gafsa ( aeb, ڨفصة '; ar, قفصة qafṣah), originally called Capsa in Latin, is the capital of Gafsa Governorate of Tunisia. It lends its Latin name to the Mesolithic Capsian culture. With a population of 111,170, Gafsa is the ninth-la ...

Network Analyzer * Charles Web Debugging Proxy * Carnivore (software) *

CommView CommView is an application for network monitoring, packet analysis, and decoding. There are two editions of CommView: the standard edition for Ethernet networks and the wireless edition for 802.11 networks named CommView for WiFi. The application ...

* dSniff * EndaceProbe Analytics Platform by Endace * ettercap *

Fiddler A fiddle is a bowed string musical instrument, most often a violin. It is a colloquial term for the violin, used by players in all genres, including classical music. Although in many cases violins and fiddles are essentially synonymous, the ...

* Kismet * Lanmeter * Microsoft Network Monitor * NarusInsight * NetScout Systems nGenius Infinistream * ngrep, Network Grep * OmniPeek, Omnipliance by Savvius * SkyGrabber *The Sniffer * snoop * tcpdump * Observer Analyzer * Wireshark (formerly known as Ethereal) * Xplico Open source Network Forensic Analysis Tool

Notes

References

External links