Sep 18, 2011 · Once a packet reaches a host using its IP address, the packet needs to be given to one of the applications on this machine. To determine which application should get the packet, it needs demultiplexing logic, which is based on ports. UDP has port information which is used by IP to deliver the packet to appropriate application.

ネットワーク系の用語で TCP/IP という表記はよく目にしますが UDP/IP という表記はあまり見ません。 TCP も UDP も、どちらも IP ネットワーク上で実装されているプロトコルなのに奇妙に思います。 なぜ TCP だけ TCP/IP と表記しがちで UDP は UDP/IP と表記しないのでしょうか？

Jun 16, 2011 · Regarding the broadcast IP addresses, both addresses are broadcast addresses but the limited broadcast address (which is 255.255.255.255) won't be forwarded by routers. It is better to use the subnet-directed broadcast address (192.168.2.255).

Basically I want to create a protocol where I send a udp packet and then I expect a response. Just like the HTTP protocol for every request there is a response. This code works if the server is on a different computer. There might be the case where the server and client are on the same computer though. Here is the server:

Jun 17, 2010 · A single IP_ADDRANY-bound UDP server should be able to appear to respond on the same dynamically-assigned IP address a packet is received on. Luckily, there is another way. Depending on your system's support you can make use of the IP_PKTINFO socket options to set or receive ancillary data about a message.

Mar 16, 2011 · UDP is a connectionless protocol - it simply has a destination and nodes simply pass it along if it comes as best as they can. So packets arriving out of order, along various routes etc are common. So Instant messengers and similar software developers think …

May 22, 2012 · In regards to why ports are specified during a multicast subscription - it's because multicast IP is just that - IP only. "ports" are a property of the upper protocols (UDP and TCP). You can read more about how multicast IP addresses map to multicast ethernet addresses at various sites. The Wikipedia article is about as good as it gets:

May 17, 2016 · Datagrams are the IP packets that provide a quick and unreliable service like UDP, and all IP packets are datagrams;[4] however, at the TCP layer, what is termed a TCP segment is the sometimes necessary IP fragmentation of a datagram,[5] but those are referred to as "packets".[6] [Emphasys added] Wiki source

I am trying to write a program to send UDP packets, as in https://wiki.python.org/moin/UdpCommunication The code appears to be in Python 2: import socket UDP_IP ...

I run the server code below to open a UDP socket. I have two network interfaces on my linux machine and two interfaces are connected to two different networks. I would like the program to listen a specified network (by assigning IP address), …