Linux well known port numbers

20 – FTP Data (For transferring FTP data)

21 – FTP Control (For starting FTP connection)

22 – SSH(For secure remote administration which uses SSL to encrypt the transmission)

23 – Telnet (For insecure remote administration

25 – SMTP(Mail Transfer Agent for e-mail server such as SEND mail)

53 – DNS(Special service which uses both TCP and UDP)

67 – Bootp

68 – DHCP

69 – TFTP(Trivial file transfer protocol uses udp protocol for connection less transmission of data)
80 – HTTP/WWW(apache)

88 – Kerberos

110 – POP3(Mail delivery Agent)

123 – NTP(Network time protocol used for time syncing uses UDP protocol)

137 – NetBIOS(nmbd)

139 – SMB-Samba(smbd)

143 – IMAP

161 – SNMP(For network monitoring)

389 – LDAP(For centralized administration)

443 – HTTPS(HTTP+SSL for secure web access)

514 – Syslogd(udp port)

636 – ldaps(both tcp and udp)

873 – rsync

989 – FTPS-data

990 – FTPS

993 – IMAPS

1194 – openVPN

1812 – RADIUS

995 – POP3s

2049 – NFS(nfsd, rpc.nfsd, rpc, portmap)

2401 – CVS server

3306 – MySql

3690 – SVN

6000-6063-X11


Regards
Gurudatta N.R