Common network protocol port number

Application Protocol port number/protocol description
FTP-data 20/tcp FTP, Data
FTP 21/tcp ftp. Control

Telnet 23/tcp

SMTP 25/tcp Simple Mail Transfer Protocol
Time 37/tcp timserver
Time 37/udp timserver
Domain 53/tcp Domain Name Server
Domain 53/udp Domain Name Server
TFTP 69/udp Trivial File Transfer
Gopher 70/tcp

HTTP 80/tcp www-HTTP World Wide Web

POP3 110/tcp Post Office Protocol-Version 3
NNTP 119/tcp Network News Transfer Protocol
NetBIOS-NS 137/tcp NetBIOS Name Service
NetBIOS-NS 137/udp NetBIOS Name Service
NetBIOS-DGM 138/udp NetBIOS datemediservice
NetBIOS-ssn139/tcp NetBIOS Session Service
IMAP 143/tcp Internet Message Access Protocol
SNMP 161/udp SNMP
SNMPTRAP 162/udp SNMP Trap
IRC 194/tcp Internet Relay Chat Protocol
IPX 213/udp IPX over IP
LDAP 389/tcp Lightweight Directory Access Protocol
HTTP 443/tcp
HTTP 443/udp
Uucp 540/tcp
LDAPS 636/tcp LDAP over TLS/SSL
Doom 666/tcp doom id software
Doom 666/udp doom id software
Phone 1167/udp conference calling
MS-SQL-s 1433/tcp Microsoft-SQL-Server
MS-SQL-s 1433/udp Microsoft-SQL-Server
MS-SQL-M 1434/tcp Microsoft-SQL-Monitor
MS-SQL-M 1434/udp Microsoft-SQL-Monitor
Wins 1512/tcp Microsoft Windows Internet Name Service
Wins 1512/udp Microsoft Windows Internet Name Service
L2TP 1701/UDP layer two Tunneling Protocol
1720/tcp
Qq 1080/udp socks proxy

Port used for BT download
The default port used by Bt is the TCP connection of 6881,6882, 6883... 6889 (only one port is used for each download and is allocated sequentially)