2.1 Common Ports

udp/5004

VoIP server

tcp/20

FTP active data transfer, transfers files between systems in plaintext

tcp/21

FTP control, used for file management between systems

tcp/22

SSH, a connection-oriented protocol used to set up secure Telnet connections for remote logins

tcp/23

Telnet, a terminal emulation program that allows for remote access to text on another computer. Not secure, transmits plaintext

tcp/25

SMTP, server/device to server email transfer

udp/53

DNS, convert hostnames to IP addresses

udp/67, udp/68

DHCP, automatic IP assignment to network clients, 67 for server, 68 for client

What is DHCP reservations?

IP addresses assigned by MAC address in the DHCP server

Dynamic/pooled addresses

IP addresses assigned in realtime from a pool. Each device is given a lease and must renew at set intervals

tcp/80

HTTP, plaintext communication between web server and client to view internet content in browser

tcp/443

HTTPS, encrypted communication between a web server and a client to view internet content in a browser

tcp/110

POP3, Basic plaintext mail transfer functionality, download emails from an email server, by authenticating and transferring.

tcp/143

IMAP4, secure mail transfer functionality with inbox management for multiple clients. Download emails from email server thru authentication and transfer

What is SMB/CIFS?

Protocol used by MS Windows for file sharing and printer sharing

What is NetBIOS?

API for communication between devices on network, works over Layer 4 and with Layer 5 protocol TCP/IP

What is NetBT?

NetBIOS over TCP/IP

udp/137

nbname, NetBIOS name service like DNS

tcp/139

nbsession, NetBIOS session service, to transfer files

tcp/445

SMB/CIFS (NetBIOS-less), direct SMB communication over TCP for shared file access without the NetBIOS transport

tcp/389

LDAP, access information in a network directory, commonly used by MS AD

tcp/3389

RDP, remote connection to computer