/etc/passwd
/etc/passwd is a file used in most UNIX and Linux systems for storing user information such as passwords.

E-911
Enhanced 911(E-911), a location technology advanced by the FCC that will enable mobile, or cellular, phones to process 911 emergency calls and enable emergency services to locate the geographic position of the caller.

EAP: Extensible Authentication Protocol
The Extensible Authentication Protocol (EAP) is for PPP authentication. EAP supports multiple, optional authentication mechanisms for PPP, including clear-text passwords, challenge-response, and arbitrary dialog sequences.

EAPoL: Extensible Authentication Protocol over LAN
EAP over LAN (EAPOL), defined in the IEEE 802.1X, offers an effective framework for authenticating and controlling user traffic to a protected network, as well as dynamically varying encryption keys. EAPOL is a standard for passing Extensible Authentication Protocol (EAP) over a wired or wireless LAN. In the wireless environment, 802.1X also describes a way for the access point and the wireless user to share and change encryption keys, and adds some messages which help smooth operations over wireless. The key change messages help solve the major security vulnerability in 802.11, the management of WEP keys. With 802.1X, WEP is brought up to an acceptable level of security for most companies.

EAPoW: Extensible Authentication Protocol over Wireless
Extensible Authentication Protocol over Wireless (EAPoW) is a term used when EAPoL(Extensible Authentication Protocol over LAN) messages are encapsulated over 802.11 wireless frames.

EAP-TLS: Extensible Authentication Protocol - Transport Layer Security
Extensible Authentication Protocol - Transport Layer Security(EAP-TLS) is an encrypted authentication scheme based on Extensible Authentication Protocol (EAP). EAP-TLS was created by Microsoft and accepted by the IETF (RFC 2716: PPP EAP TLS Authentication Protocol).

EAP-TTLS: Extensible Authentication Protocol–Tunneled Transport Layer Security
Extensible Authentication Protocol–Tunneled Transport Layer Security (EAP-TTLS) is an encrypted authentication scheme based on Extensible Authentication Protocol (EAP) and easier to manage than Extensible Authentication Protocol–Transport Layer Security (EAP-TLS). EAP-TTLS is a proprietary protocol which was developed by Funk Software and Certicom, and is supported by some other vendors.

EAR: Export Administration Regulations
Export Administration is an US federal government organization under the Department of Commerce. Export Administration Regulations(EAR) are the rules and regulations for export control set by the oganizaton. Secuity related products are administrated by this agency for export.

Eavesdropping
Eavesdropping or wiretapping is simply listening to a private conversation. In the security and IT worlds, it extends to remote listening and recording devices, including the interception of telephone calls, fax transmissions, e-mails, data transmissions, data-scoping, and even radio scanning for mobile communications.

ECB: Electronic Code Book
Electronic Code Book (ECB) is a mode of operation for a block cipher, with the characteristic that each possible block of plaintext has a defined corresponding ciphertext value and vice versa. In other words, the same plaintext value will always result in the same ciphertext value.

ECC: elliptical curve cryptography
Elliptical curve cryptography (ECC) is a public key encryption technique based on elliptic curve theory that can be used to create faster, smaller, and more efficient cryptographic keys. ECC generates keys through the properties of the elliptic curve equation instead of the traditional method of generation as the product of very large prime numbers.

ECDSA: Elliptic Curve Digital Signature Algorithm
Elliptic Curve Digital Signature Algorithm (ECDSA) is a standard that is the elliptic curve cryptography analog of the Digital Signature Algorithm. ECDSA was accepted in 1999 as an ANSI standard, and was accepted in 2000 as IEEE and NIST standards. It was also accepted in 1998 as an ISO standard.

Echelon
Echelon is an officially unacknowledged U.S.-led global spy network that operates an automated system for the interception and relay of electronic communications. Echelon evolved out of Cold War espionage arrangements set up by the US and UK in 1948, and later brought in Australia, Canada and New Zealand. Monitored transmissions are said to include up to 3 billion communications daily, including all the telephone calls, e-mail messages, faxes, satellite transmissions, and Internet downloads of both public and private organizations and citizens worldwide.

Echo Reply
An echo reply is the response a system that has received an echo request sent over ICMP.

Echo Request
An echo request is an ICMP message sent to a system to determine if it is online and how long the traffic takes to get to it.

ECSS: Extended-Certificate Syntax Standard
Extended-Certificate Syntax Standard(ECSS) is a Public -Key Cryptography Standard (PKCS) that deals with extended certificates, which are made up of the X.509 certificate plus aditional attributes. The additional attributes and the X.509 certificate can be verified using a single public-key operation.

EES: Escrowed Encryption Standard
The Escrowed Encryption Standard (EES) is a standard for encrypted communications approved by the U.S. Department of Commerce in 1994. It is better known by the name of Clipper chip. The significant feature of EES is its so-called key escrow method of enabling eavesdropping by authorized government agencies under certain circumstances.

EFS: Encrypting File System
The Encrypting File System (EFS) is a feature of the Windows 2000 operating system that lets any file or folder be stored in encrypted form and decrypted only by an individual user and an authorized recovery agent. EFS is especially useful for mobile computer users, whose computer (and files) are subject to physical theft, and for storing highly sensitive data.

Egress Filtering
Egress Filtering means filtering outbound traffic.

EICAR test file
The EICAR test file, developed by the EICAR organization, is used in testing anti-virus scanners for their integrity in detecting viruses. The actual file is simply a text file of either 68 or 70 bytes that can be created using any text editing program (Such as Notepad), although it can be saved and run as an executable MS-DOS COM file. Its use can be more versatile than straightforward detection - for example, a file containing the Eicar test string can be compressed or archived, and then the antivirus software can be run to see whether it can detect the test string in the compressed file.

EICAR: European Institute of Computer Anti-Virus Research
European Institute of Computer Anti-Virus Research (EICAR), founded in 1990, is an organization aiming to further antivirus research and improving development of antivirus software. EICAR has furthered their scope to include the research of malicious software (malware) other than computer viruses. They are perhaps most notable for the Eicar test file, an innocent, executable string, designed to test the integrity of antivirus software. Its use can be more versatile than straightforward detection, for example, a file containing the Eicar test string can be compressed, and then the antivirus software can be run to see whether it can detect the test string in the compressed file.

EKE: Encrypted Key Exchange
Encrypted Key Exchange (EKE) is a method of sharing a secret message between two parties that involves using a short password as the primary key.

El Gamal
El Gamal is the encryption algorithm that forms the basis of the digital signature algorithm (DSA).

Electrohippies Collective
The Electrohippies Collective is an international group of hacktivists based in Oxfordshire, England, whose purpose is to express its displeasure with the use of the Internet "as a tool for corporate communications and propaganda." A common form of protest used by The Electrohippies Collective is the Web sit-in.

Elk Cloner
Elk Cloner was the first computer virus (1982) known to have spread in the world.

EMAIL Attack
The common form of email attack is spam, including phishing. Of the billions email messages that are sent worldwide each day, at least one-third are unsolicited commercial email, in other words—spam. Of that spam emails, porn spam email accounts for at least 25%.

EMAIL Authentication
EMAIL Authentication refers to ensuring a valid identity on an email to prove and protect email sender identity. It has become a vital first step in stopping spam, forgery, fraud, and even more serious crimes. An essential second step will be Ensuring the entity has a good reputation,and technologies such as DomainKey have been developed for this purpose.

E-mail Forgery
E-mail forgery means using an e-mail header so that the message appears to have originated from someone or somewhere other than the actual source. Distributors of spam often use spoofing in an attempt to get recipients to open, and possibly even respond to, their solicitations.

E-mail Spoofing
E-mail spoofing is the forgery of an e-mail header so that the message appears to have originated from someone or somewhere other than the actual source. Distributors of spam often use spoofing in an attempt to get recipients to open, and possibly even respond to, their solicitations. Spoofing can be used legitimately.

Emanation Monitoring
Emanation monitoring is to monitor electric or electromagnetic radiation emanations from electronic equipment including microchips, monitors, printers, and all electronic devices emit radiation through the air or through conductors (such as wiring or water pipes). Tempest was the name of a classified (secret) U.S. government project to study the susceptibility of some computer and telecommunications devices to emit electromagnetic radiation (EMR) in a manner that can be used to reconstruct intelligible data.

Emanations Analysis
Emanations Analysis means gaining direct knowledge of communicated data by monitoring and resolving a signal that is emitted by a system and that contains the data but is not intended to communicate the data.

Encrypted data
Encrypted data refers to the data that has been converted from plaintext into ciphertext. Encrypted messages are used to disguise the content of a message when it is sent or stored.

Encapsulation
Encapsulation means the inclusion of one data structure within another structure so that the first data structure is hidden for the time being.

Encryption
Encryption refers to the cryptographic transformation of plaintext or cleartext data into a form called "cipher text" that conceals the data's original meaning to prevent it from being known or used.

Encryption Certificate
Encryption Certificate, a public-key certificate, contains a public key that is intended to be used for encrypting data, rather than for verifying digital signatures or performing other cryptographic functions.

Encryption algorithm
Encryption algorithm refers to a mathematical procedure for converting plaintext into ciphertext.

End-to-end Encryption
End-to-end Encryption refers to a complete protection of data that flows between two points in a network, in which the data is encrypted when it leaves its source, leaving it encrypted while it passes through any intermediate computers (such as routers), and decrypting only when the data arrives at the intended destination.

Enumeration
Enumeration is the process of gathering information about a target system or network a hacker wants to compromise.

EoP: Elevation of privileges
Elevation of privileges (EoP) refers to any method used by attackers to gain control of a system or network.

Ephemeral Key
Ephemeral Key is a public key or a private key that is relatively short-lived.

Ephemeral Port
Ephemeral Port, also called a transient port or a temporary port, is set up when a client application wants to connect to a server and is destroyed when the client application terminates. It has a port number chosen at random that is greater than 1023.

EPIC: Electronic Privacy Information Center
Electronic Privacy Information Center (EPIC) is a public interest organization focusing on civil liberties and privacy issues.

Escrow Passwords
Escrow Passwords are passwords that are written down and stored in a secure location (like a safe) that are used by emergency personnel when privileged personnel are unavailable.

E-SIGN Act: Electronic Signatures in Global and National Commerce Act
Electronic Signatures in Global and National Commerce Act (E-SIGN Act) is a U.S. law governing the use of digital signatures in business and commerce.

E-Signature
E-Signature, also called a digital signature, is an electronic signature that can be used to authenticate the identity of the sender of a message or the signer of a document, and possibly to ensure that the original content of the message or document that has been sent is unchanged.

ESP: Encapsulating Security Payload
Encapsulating Security Payload (ESP), a key protocol in the IPsec (Internet Security) architecture, is designed to provide a mix of security services in IPv4 and IPv6. The IP Encapsulating Security Payload (ESP) seeks to provide confidentiality and integrity by encrypting data to be protected and by placing the encrypted data in the data portion of the IP ESP. Depending on the user's security requirements, this mechanism may be used to encrypt either a transport-layer segment (e.g., TCP, UDP, ICMP, IGMP) or an entire IP datagram. Encapsulating the protected data is necessary to provide confidentiality for the entire original datagram.

Ethereal
Ethereal, now called Wireshark, is an open source and popular network troubleshooting and packet sniffing tool for both UNIX and Microsoft Windows operating systems. Similar to tcpdump but with a well-designed GUI and many more information sorting and filtering options, Ethereal allows the user to see all traffic being passed over the network by putting the network card into a promiscuous mode. It could be used by hackers to view network traffic information without authorization.

Ethical Hacker
An ethical hacker is a computer and network expert who attacks a security system on behalf of its owners, seeking vulnerabilities that a malicious hacker could exploit. To test a security system, ethical hackers use the same methods as if they are the real hackers, but report problems instead of taking advantage of them.

Ethical Hacking
Ethical hacking is also known as penetration testing, intrusion testing, and red teaming. It is conducted by ethical hackers to find possible problems in the system.

Ethical Worm
An ethical worm is a program that automates network-based distribution of security patches for known vulnerabilities. Similar to the malicious worms, the ethical worm could propagate across networks exponentially and perform its tasks without user knowledge or consent, through a process sometimes called a drive-by download.

Event logs
Event logs refers to tue logs that record certain types of system information on Microsoft Windows platforms.

Evil Twin
In security, an evil twin is a home-made wireless access point (hot spot) that masquerades as a legitimate one to gather personal or corporate information without the end-user's knowledge. It's fairly easy for an attacker to create an evil twin by simply using a laptop, a wireless card and some readily-available software.

Exploit
In computing, an exploit is an attack on a computer system, especially one that takes advantage of a particular vulnerability that the system offers to intruders. Used as a verb, the term refers to the act of successfully making such an attack.

Exponential Backoff Algorithm
An exponential backoff algorithm is used to adjust TCP timeout values on the fly so that network devices don't continue to timeout sending data over saturated links.

Exposure
Exposure is a threat action whereby sensitive data is directly released to an unauthorized entity.

Extended ACLs
Extended ACLs are a more powerful form of Standard ACLs on Cisco routers. They can make filtering decisions based on IP addresses (source or destination), Ports (source or destination), protocols, and whether a session is established.