Important Protocols -Port Numbers (L4): Protocol Service Expansion Port No(TCP/UDP) FTP File Transfer Protocol 21/21/TCP SSH Secure Shell 22/22/TCP TELNET Terminal Network 23/23/TCP SMTP Simple Mail Transfer Protocol 25/25/TCP DNS Domain Naming System 53/53/TCP & UDP DHCP Dynamic Host Configuration Protocol 67/67/UDP –Server 68/UDP for Client TFTP Trivial File Transfer Protocol 69/69/UDP HTTP Hypertext Transfer Protocol 80/80/TCP POP3 Post Office Protocol 110/110/TCP NTP Network Time Protocol 123/123/UDP IMAP Internet Message Access Protocol 143/143/TCP SNMP Simple Network Management Protocol 161/161/TCP HTTPS HTTP secure 443/443/TCP SYSLOG System Log 514/514/UDP LPD Line Printer Daemon 515/TCP RSTP Real Time Stream Protocol 554/TCP IPP Internet Printing Protocol 631/TCP Flexlm FLEXible License Manager 744/UDP SWAT Samba Web Administration Tool 901/TCP IMAPS Interactive Mail Access Protocol Secure version 4 993/TCP IRCS Internet Relay Chat Secure 994/TCP POP3s Post Office Protocol Secure version 3 995/TCP NFS Network File System by Sun) 613/TCP&UDP CVSPserver Concurrent Version System Password server […]
Ports are logical channels to enter into the Server/ Computer for a specific program. Ports were developed so that computers could accept data from multiple sources over the same IP address. There are 65,535 TCP and UDP ports available to transmit data but Ports 0-1023 are reserved for common use and designated as well-known ports. These ports are assigned by the IANA (Internet Assigned Numbering Authority). This means, that every port from 0-1023 will be the same on every system. This list of well-known port numbers specifies the port used by the Server for specific Server program.