Network+ 1.4 common network ports

File transfer protocol

20 (data transfer) / 21 (commands and responses)

Secure file transfer protocol

22

FTP over SSH

SSH (secure shell)

22

Encrypted command CLI

Telnet

23

Simple Mail transfer protocol 25

25

Sensing mail

DNS

UDP 53 (or tcp)

DHCP (dynamic host configuration protocol)

UDP 67 (server) / 68 (client)

TFTP (trivial file transfer protocol)

UDP 69

Small file transfers (router/switch boot configs)

HTTP (hypertext transfer protocol)

80

NTP( Network time protocol)

UDP 123

Synchronizes computer clocks on network

IMAP (internet message access protocol)

143

SNMP(simple network message protocol)

TCP/UDP161 (commands) /162 (device response)

V3 only

Manage devices on network (IP) e.g., routers etc)

LDAP (lightweight directory access protocol)

389

Used for querying and modifying items in directory service databases

HTTPS/TLS

443

SMB (server message block)

TCP 445

Windows file sharing, printing

Syslog

UDP (commonly), TCP, or SSL/TLS

514

SMTPS

587

Over TLS

LDAPS

636

Over SSL

POP3

110

POP3 over ssl

995

IMAP over SSL

993

SQL Server

1433 TCP

RDP

3389 TCP

SIP (session initiation protocol)

5060 (unsecured) / 5061 (secured,TLS)

VOIP calls session startup

ICMP (internet control message protocol)

Diagnostic/control messages (ping echo request/reply)

*ping is not a protocol it uses the ICMP

TCP (transmission control protocol)

Acknowledge: used between sender and receiver to verify and recover data.

Flow control: prevents one host from overflowing buffers.

Windowing (speed up flow): defines the amount of data the receiver will wait to receive before it sends ACKs.

Sequence #: used in segments to verify their order and to help recover

3-way handshake

Sender ——receiver

Syn—>

←ack/syn

Ack —>

generic routing protocol (GRE)

Cisco tunneling protocol—-encapsulates protocols in IP tunnels

Common for VPNs

IPSEC

Secures IP communications via authentication + encryption

-transport: encrypts payload only (header untouched)

-tunnel mode: encrypts header + payload (used for VPNs)

Authentication header

Auth + integrity

No encryption

Encapsulating security protocol (ESP)

Everything from AH but add encryption