Network + Ports & Protocol

Alternate secure SMTP port

587

Default HTTP port ?

80

DHCP Ports

UDP 67 (server), UDP 68 (client)

DHCP Purpose

Assign IP, subnet mask, gateway, DNS

DNS Port

TCP/UDP 53

DNS Purpose

Translate domain names to IP addresses

FTP Ports

20 (data), 21 (control)

FTP Purpose

File transfer

HTTP Port

80

HTTP purpose → Unencrypted web traffic

Unencrypted web traffic

HTTPS Port

443

HTTPS Purpose

Encrypted web traffic (SSL/TLS)

IMAP Port

143

IMAP Purpose

Receive email (keeps messages on server)

IP role

Connectionless delivery; no session

NTP Port

123

NTP Purpose

Time synchronization

POP3 Port

110

POP3 Purpose

Receive email (downloads messages)

Protocol agreement between devices

Exchange data

Purpose of a port number

Deliver data to a specific application

RDP Port

3389

RDP Purpose

Remote desktop access

SFTP Port

22

SFTP Purpose

Secure file transfer over SSH

SIP Ports

5060/5061

SIP Purpose

VoIP session control

SMB port

445

SMB Purpose

File & printer sharing

SMTP Port

25

SMTP Purpose

Send email from client & between servers

SNMP Ports

UDP 161/162

SNMP Purpose

Network device monitoring

SSH port

22

SSH purpose

Secure remote login, encrypted

TCP Role

Reliable delivery; reorders packets

Telnet port → 23

23

Telnet Purpose

Remote login (insecure)

TFTP Port

69

TFTP Purpose

Simple, insecure file transfer

Why combine protocols?

Use strengths of each

Why list protocol + port together?

Identify specific process

Why replace Telnet?

No encryption