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The Simple Mail Transfer Protocol (SMTP) is an Internet standard communication protocol for electronic mail transmission. Mail servers and other message transfer agents use SMTP to send and receive mail messages. User-level email clients typically use SMTP only for sending messages to a mail server for relaying, and typically submit outgoing email to the mail server on port 587 or 465 per RFC 8314. For retrieving messages, IMAP is standard, but proprietary servers also often implement proprietary protocols, e.g., Exchange ActiveSync.
The Secure Shell Protocol (SSH) is a cryptographic network protocol for operating network services securely over an unsecured network. Its most notable applications are remote login and command-line execution.
In computing, a denial-of-service attack is a cyber-attack in which the perpetrator seeks to make a machine or network resource unavailable to its intended users by temporarily or indefinitely disrupting services of a host connected to a network. Denial of service is typically accomplished by flooding the targeted machine or resource with superfluous requests in an attempt to overload systems and prevent some or all legitimate requests from being fulfilled.
The File Transfer Protocol (FTP) is a standard communication protocol used for the transfer of computer files from a server to a client on a computer network. FTP is built on a client–server model architecture using separate control and data connections between the client and the server. FTP users may authenticate themselves with a plain-text sign-in protocol, normally in the form of a username and password, but can connect anonymously if the server is configured to allow it. For secure transmission that protects the username and password, and encrypts the content, FTP is often secured with SSL/TLS (FTPS) or replaced with SSH File Transfer Protocol (SFTP).
In computer networking, a proxy server is a server application that acts as an intermediary between a client requesting a resource and the server providing that resource. It improves privacy, security, and performance in the process.
In information security, a confused deputy is a computer program that is tricked by another program into misusing its authority on the system. It is a specific type of privilege escalation. The confused deputy problem is often cited as an example of why capability-based security is important.
SOCKS is an Internet protocol that exchanges network packets between a client and server through a proxy server. SOCKS5 optionally provides authentication so only authorized users may access a server. Practically, a SOCKS server proxies TCP connections to an arbitrary IP address, and provides a means for UDP packets to be forwarded.
Info-ZIP is a set of open-source software to handle ZIP archives. It has been in circulation since 1989. It consists of 4 separately-installable packages: the Zip and UnZip command-line utilities; and WiZ and MacZip, which are graphical user interfaces for archiving programs in Microsoft Windows and classic Mac OS, respectively.
Nmap is a network scanner created by Gordon Lyon. Nmap is used to discover hosts and services on a computer network by sending packets and analyzing the responses.
A port scanner is an application designed to probe a server or host for open ports. Such an application may be used by administrators to verify security policies of their networks and by attackers to identify network services running on a host and exploit vulnerabilities.
In computer networking, port forwarding or port mapping is an application of network address translation (NAT) that redirects a communication request from one address and port number combination to another while the packets are traversing a network gateway, such as a router or firewall. This technique is most commonly used to make services on a host residing on a protected or masqueraded (internal) network available to hosts on the opposite side of the gateway, by remapping the destination IP address and port number of the communication to an internal host.
A BNC is a piece of software that is used to relay traffic and connections in computer networks, much like a proxy. Using a BNC allows a user to hide the original source of the user's connection, providing privacy as well as the ability to route traffic through a specific location. A BNC can also be used to hide the true target to which a user connects.
File eXchange Protocol is a method of data transfer which uses FTP to transfer data from one remote server to another (inter-server) without routing this data through the client's connection. Conventional FTP involves a single server and a single client; all data transmission is done between these two. In the FXP session, a client maintains a standard FTP connection to two servers, and can direct either server to connect to the other to initiate a data transfer. The advantage of using FXP over FTP is evident when a high-bandwidth server demands resources from another high-bandwidth server, but only a low-bandwidth client, such as a network administrator working away from location, has the authority to access the resources on both servers.
FTPS is an extension to the commonly used File Transfer Protocol (FTP) that adds support for the Transport Layer Security (TLS) and, formerly, the Secure Sockets Layer cryptographic protocols.
WEBrick is a Ruby library providing simple HTTP web servers. It uses basic access authentication and digest access authentication for different kinds of servers that it can create - HTTP based server, HTTPS server, proxy server and virtual-host server. Construction of several non-HTTP servers such as the Day Time Server which uses the Daytime Protocol rather than the HTTP is also facilitated by WEBrick. It is used by the Ruby on Rails and Padrino frameworks to test applications in a development environment as well as production mode for small loads. It is now a part of Ruby standard library.
In security parlance, the term open port is used to mean a TCP or UDP port number that is configured to accept packets. In contrast, a port which rejects connections or ignores all packets directed at it is called a closed port.
An application-level gateway is a security component that augments a firewall or NAT employed in a computer network. It allows customized NAT traversal filters to be plugged into the gateway to support address and port translation for certain application layer "control/data" protocols such as FTP, BitTorrent, SIP, RTSP, file transfer in IM applications. In order for these protocols to work through NAT or a firewall, either the application has to know about an address/port number combination that allows incoming packets, or the NAT has to monitor the control traffic and open up port mappings dynamically as required. Legitimate application data can thus be passed through the security checks of the firewall or NAT that would have otherwise restricted the traffic for not meeting its limited filter criteria.
An idle scan is a TCP port scan method for determining what services are open on a target computer without leaving traces pointing back at oneself. This is accomplished by using packet spoofing to impersonate another computer so that the target believes it's being accessed by the zombie. The target will respond in different ways depending on whether the port is open, which can in turn be detected by querying the zombie.
Banner grabbing is a technique used to gain information about a computer system on a network and the services running on its open ports. Administrators can use this to take inventory of the systems and services on their network. However, an intruder can use banner grabbing in order to find network hosts that are running versions of applications and operating systems with known exploits.
A web shell is a shell-like interface that enables a web server to be remotely accessed, often for the purposes of cyberattacks. A web shell is unique in that a web browser is used to interact with it.
References
- ↑ M. Allman; S. Ostermann (1999). "RFC 2577". doi:10.17487/RFC2577.
- ↑ "ftp-bounce", Nmap Scripting Engine documentation
