Security+ Port Numbers

File Transfer Protocol (FTP)

20/21 Port 21 is the control port while port 20 is used to transfer files.

Secure Shell (SSH)

22 Designed to transmit data through a remote connection.

SSH File Transfer Protocol

22 A separate protocol from FTP that uses SSH to encrypt file transfers.

Simple Mail Transfer Protocol (SMTP)

25 Internet mail protocol used to send outgoing mail from email clients to mail servers.

TACACS+

49 Cisco proprietary protocol used for AAA services.

Domain Name System (DNS)

53 Used to associate IP addresses with domain names.

Dynamic Host Configuration Protocol (DHCP)

67/68 Assigns multiple local private IP addresses from one public IPv4 address.

Hypertext Transfer Protocol (HTTP)

80 Protocol used for websites and most internet traffic.

Kerberos

88 Network authentication protocol that allows for communication over a non-secure network.

Post Office Protocol (POP)

110 Allows email clients to communicate with email servers; provides one-way communication.

Network Time Protocol (NTP)

123 Low latency protocol used to synchronize timekeeping across a network.

Server Message Block (SMB)

139 Windows proprietary protocol built on NetBIOS; allows remote server access (originally used port 139 over UDP).

Internet Message Access Protocol (IMAP)

143, 993 Email protocol for clients to communicate with servers; provides two-way communication.

Simple Network Management Protocol (SNMP)

161/162 Protocol used to monitor and manage network devices on IP networks.

Lightweight Directory Access Protocol (LDAP)

389 Used to manage and communicate with directories.

Hypertext Transfer Protocol Secure (HTTPS)

443 Secure version of HTTP that uses TLS for encryption.

Secure Socket Tunneling Protocol (SSTP)

443 Microsoft-developed tunneling protocol replacing PPTP or L2TP/IPSec in Windows; uses TLS.

Server Message Block (SMB)

445 Windows proprietary protocol built on NetBIOS; allows remote server access (modern versions use port 445 over TCP).

IPSec (ISAKMP)

500 Internet Protocol security using ISAKMP - Internet Security Association and Key Management Protocol.

Secure SMTP (SMTPS)

587 Secure version of SMTP using TLS for encryption.

Lightweight Directory Access Protocol Secure (LDAPS)

636 Secure version of LDAP that uses TLS for encryption.

File Transfer Protocol Secure (FTPS)

989/990 FTPS uses TLS for encryption; sometimes allocated to ports 989/990 instead of 20/21.

Internet Message Access Protocol Secure (IMAPS)

993 Secure version of IMAP that uses TLS for encryption.

Post Office Protocol 3 Secure (POP3S)

995 Secure version of POP that uses TLS for encryption.

Remote Authentication Dial-In User Service (RADIUS)

1812, 1813 Used to provide AAA for network services.

Remote Desktop Protocol (RDP)

3389 Enables remote connections to other computers (Windows proprietary protocol).

Diameter

3868 Developed as an upgrade to RADIUS.

Secure Real Time Protocol (SRTP)

5004 Replaced RTP; used to stream audio and video communication using UDP.

Transmission Control Protocol (TCP)

N/A One of two main IP suite protocols; provides error checking to ensure packets are not lost in transit.

User Datagram Protocol (UDP)

N/A Second main IP suite protocol; transmits datagrams in a best-effort method without error checking.

Point to Point Tunneling Protocol (PPTP)

1723 Based on PPP; deprecated protocol for VPNs.

Layer 2 Tunneling Protocol (L2TP)

1701 Creates point-to-point connections like VPNs over UDP; needs IPsec for encryption; extension to PPTP and operates at data link layer.

Point to Point Tunneling Protocol (PPTP)

1723 Based on PPP; deprecated protocol for VPNs.