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Local port forwarding is the most common type of port forwarding. It is used to let a user connect from the local computer to another server, i.e. forward data securely from another client application running on the same computer as a Secure Shell (SSH) client. By using local port forwarding, firewalls that block certain web pages, can be ...
This is a list of TCP and UDP port numbers used by protocols for operation of network applications. The Transmission Control Protocol (TCP) and the User Datagram Protocol (UDP) only need one port for bidirectional traffic. TCP usually uses port numbers that match the services of the corresponding UDP implementations, if they exist, and vice versa.
UDP is a simple message-oriented transport layer protocol that is documented in RFC 768.Although UDP provides integrity verification (via checksum) of the header and payload, [4] it provides no guarantees to the upper layer protocol for message delivery and the UDP layer retains no state of UDP messages once sent.
netcat (often abbreviated to nc) is a computer networking utility for reading from and writing to network connections using TCP or UDP.The command is designed to be a dependable back-end that can be used directly or easily driven by other programs and scripts.
The use of UDP helper addresses can cause issues with some Windows-based network configurations.. [2] According to Microsoft these issues stem from the fact that ports 137,138 are forwarded by default on Cisco routers. Since these ports are used by NetBIOS to help determine network configuration the added broadcasts can confuse the system.
Web Cache Communication Protocol (WCCP) is a Cisco-developed content-routing protocol that provides a mechanism to redirect traffic flows in real-time. It has built-in load balancing , scaling, fault tolerance, and service-assurance (failsafe) mechanisms.
On the other hand, for UDP, NATs do not need port preservation. Indeed, multiple UDP communications (each with a distinct endpoint) can occur on the same source port, and applications usually reuse the same UDP socket to send packets to distinct hosts. This makes port prediction straightforward, as it is the same source port for each packet.
For TCP, port number 0 is reserved and cannot be used, while for UDP, the source port is optional and a value of zero means no port. A process associates its input or output channels via an internet socket , which is a type of file descriptor , associated with a transport protocol , a network address such as an IP address , and a port number.