1 aa513bf8 2023-01-22 jrmu version=pmwiki-2.2.130 ordered=1 urlencoded=1
2 aa513bf8 2023-01-22 jrmu agent=Mozilla/5.0 (X11; OpenBSD amd64; rv:76.0) Gecko/20100101 Firefox/76.0
4 aa513bf8 2023-01-22 jrmu charset=UTF-8
6 aa513bf8 2023-01-22 jrmu ctime=1597203074
7 aa513bf8 2023-01-22 jrmu host=38.81.163.143
8 aa513bf8 2023-01-22 jrmu name=Openbsd.Sockets
11 aa513bf8 2023-01-22 jrmu text=Every computer on the internet uses the Internet Protocol (IP). There are two protocols that are added on top of IP: Transmission Control Protocol (TCP) and User Datagram Protocol (UDP).%0a%0aTCP is used when we need to send data in a reliable way (for example, email uses TCP because you don't want to lose any words!). UDP is used when some data loss is acceptable and speed is most important (for example, a slightly worse quality voice call is not a big deal). You can learn more about common applications, their protocols, and their ports by viewing /etc/services.%0a%0aTCP/IP is used to carry basic packets. Inside those packets, we have different protocols to describe different applications. Common applications include SMTP for email, FTP for uploading/downloading files, SSH for remotely connecting to computers, HTTP for the world wide web, IRC for text messages and chat, and so on.%0a%0aEach computer has network interfaces to connect it with the global Internet. Each network interface will have at least one IP address, which will look something like 192.168.0.1. Each IP address can have any number of ports from 1 to 65535. When you combine an IP address with a port, you have a socket. For example, 192.168.0.1:443 is the socket that your web server (openhttpd) listens on.%0a%0aTCP/IP relies on client-server architecture. One thing will act as the server, and another the client. The client requests something, and the server delivers it. For example, if you use your phone to view a video, your phone is the client, and the server is in a mysterious data center somewhere. The server is often an expensive, professional machine in an expensive data center, but not always. Any computer running the right software can act as a server. For example, your home desktop PC could run an IRC server and serve chat messages which your phone could request. Your phone could even run a web server and deliver web pages. The important thing to remember is that the client requests information and a server responds to it. %0a%0aEvery client must specify a unique socket with a specific protocol, and the server must listen on that exact same combination in order to respond. For example, if you request from a web server with IP 192.168.0.1 on port 443 using TCP, if the web server is listening on a different socket (IP 192.168.0.1 port 80 using TCP), your web server will '''not''' be able to respond. Port 443 is not the same as port 80. Both the socket and protocol must be identical. If the IP addres, port, or protocol type is wrong, the client-server connection will not work.%0a%0aInternet Control Message Protocol (ICMP)%0aIPv6%0a%0aNetwork address translation (NAT)%0aDNS%0aSSL/TLS%0asubnetting%0aEthernet MAC address%0ahex and /24%0afor example , 0xffffff00%0aSubnet Mask and Default Gateway%0a%0areserved ip addresses%0a%0aloopback ip addresses: 127.0.0.0 to 127.255.255.255.%0a%0aSome devices have multiple network interfaces
12 aa513bf8 2023-01-22 jrmu time=1597204106
13 aa513bf8 2023-01-22 jrmu author:1597204106=jrmu
14 aa513bf8 2023-01-22 jrmu diff:1597204106:1597203074:=18,29c18%0a%3c SSL/TLS%0a%3c subnetting%0a%3c Ethernet MAC address%0a%3c hex and /24%0a%3c for example , 0xffffff00%0a%3c Subnet Mask and Default Gateway%0a%3c %0a%3c reserved ip addresses%0a%3c %0a%3c loopback ip addresses: 127.0.0.0 to 127.255.255.255.%0a%3c %0a%3c Some devices have multiple network interfaces%0a\ No newline at end of file%0a---%0a> SSL/TLS%0a\ No newline at end of file%0a
15 aa513bf8 2023-01-22 jrmu host:1597204106=38.81.163.143
16 aa513bf8 2023-01-22 jrmu author:1597203074=jrmu
17 aa513bf8 2023-01-22 jrmu diff:1597203074:1597203074:=1,18d0%0a%3c Every computer on the internet uses the Internet Protocol (IP). There are two protocols that are added on top of IP: Transmission Control Protocol (TCP) and User Datagram Protocol (UDP).%0a%3c %0a%3c TCP is used when we need to send data in a reliable way (for example, email uses TCP because you don't want to lose any words!). UDP is used when some data loss is acceptable and speed is most important (for example, a slightly worse quality voice call is not a big deal). You can learn more about common applications, their protocols, and their ports by viewing /etc/services.%0a%3c %0a%3c TCP/IP is used to carry basic packets. Inside those packets, we have different protocols to describe different applications. Common applications include SMTP for email, FTP for uploading/downloading files, SSH for remotely connecting to computers, HTTP for the world wide web, IRC for text messages and chat, and so on.%0a%3c %0a%3c Each computer has network interfaces to connect it with the global Internet. Each network interface will have at least one IP address, which will look something like 192.168.0.1. Each IP address can have any number of ports from 1 to 65535. When you combine an IP address with a port, you have a socket. For example, 192.168.0.1:443 is the socket that your web server (openhttpd) listens on.%0a%3c %0a%3c TCP/IP relies on client-server architecture. One thing will act as the server, and another the client. The client requests something, and the server delivers it. For example, if you use your phone to view a video, your phone is the client, and the server is in a mysterious data center somewhere. The server is often an expensive, professional machine in an expensive data center, but not always. Any computer running the right software can act as a server. For example, your home desktop PC could run an IRC server and serve chat messages which your phone could request. Your phone could even run a web server and deliver web pages. The important thing to remember is that the client requests information and a server responds to it. %0a%3c %0a%3c Every client must specify a unique socket with a specific protocol, and the server must listen on that exact same combination in order to respond. For example, if you request from a web server with IP 192.168.0.1 on port 443 using TCP, if the web server is listening on a different socket (IP 192.168.0.1 port 80 using TCP), your web server will '''not''' be able to respond. Port 443 is not the same as port 80. Both the socket and protocol must be identical. If the IP addres, port, or protocol type is wrong, the client-server connection will not work.%0a%3c %0a%3c Internet Control Message Protocol (ICMP)%0a%3c IPv6%0a%3c %0a%3c Network address translation (NAT)%0a%3c DNS%0a%3c SSL/TLS%0a\ No newline at end of file%0a
18 aa513bf8 2023-01-22 jrmu host:1597203074=38.81.163.143
