Common Ports

There’s the ports everyone knows, like telnet and ftp but being out of the networking for a while i’ve forgotten some and I learned others

This was a good refreasher for me and I came away with some of the ports i hadn’t known.


Telnet tcp/23
	Nonencrypted, in the clear
SSH tcp/22
	Looks and feel of telnet

DNS udp/53
	Domain name to ipaddress
SMTP Simple Mail Transfer Protocol tcp/25
	Email server
	Used for outgoing mail
SFTP tcp/22 secure File transfer protocol
	Uses SSH, that's why same port
	Can resume interrupted transfers
	Has remote file removal
	Has directory listing
FTP tcp/20 (active mode data) tcp/21(control)
	Transfers files
	Has username/password
	List, add, delete..
Tftp udp/69 trivial file transfer protocal
	No login
	Reads and writes
DHCP udp/67, udp/68 Dynamic Host Configuration Protocol
	Required DHCP server
	Pool of ip addresses
	Has lease time and must renew ip at set intervals
	DHCP reservations
		Addresses are assigned by MAC address in DHCP server
		Quickly Manage from 1 location
		Servers, printers…
HTTP tcp/80 HTTPS tcp/443
	Hyper text protocol
	Communication in the browser
	Can be used by other applications
	HTTP = in the  clear
	HTTPS = encrypted

SNMP upd/161 Simple Network Management Protocol
	Different versions
		V.1 structured tables, in the clear
		V.2 Data type enhancements, bulk transfers, still in clear
		V.3 Message integrity, Authentication, encryption

Rdp tcp/3389 Remote Desktop Protocol
	On many windows systems
	Can connect to entire desktop or just application
	Clients for Win, MAcOS, Linux, Unix, iPhone

NTP udp/123 Network Time Protocol
	Sets time for device
	Syncs all devices
	Used for Authentication
	You control when clocks are updated
	Very Accurate (better then 1 millisecond on local network)
VOIP tcp/5060 and tcp/5061 (SIP Session Initiation Protocol)
	Voice over IP Signaling
	Doing all call
	Adds video, instant messaging, file transfer
SMB Server Message Block tcp/445
	Protocol used my Microsoft
	File Sharing
	Print Sharing
	Also called CIFS (Common Internet File System)
PoP/Imap tcp/110 POP3
	Basic Mail Transfer
	IMAP4 tcp/143
		Includes management of email inbox from multiple clients. (desktop and iPhone)
LDAP tcp/389 Lightweight Directory Access Protocol
	Store and receive data in a network directory
LDAPS(LDAP Secure) tcp/636
	Non-standard of ldap over SSL
H.323 tcp/1720
	Also VOIP
		ITU Telecommunication h.23 protocol series
		Does all all call things
		Early. But still used today.