| Question | Answer |
| 21 | FTP
File Transfer Protocol is used to transfer files from host to host |
| 22 | SSH, SCP, SFTP
Secure Shell is used to remotely administer network devices and systems. SCP is used for
secure copy and SFTP for secure FTP. |
| 23 | Telnet
Unencrypted method to remotely administer network devices (should not be used) |
| 25 | SMTP
Simple Mail Transfer Protocol is used to send email over the Internet |
| 69 | TFTP
Trivial FTP is used as a simplified version of FTP to put a file on a remote host, or get a file
from a remote host |
| 80 | HTTP
Hyper Text Transfer Protocol is used to transmit web page data to a client for unsecured web
browsing |
| 88 | Kerberos
Used for network authentication using a system of tickets within a Windows domain |
| 110 | POP3
Post Office Protocol v3 is used to receive email from a mail server |
| 119 | NNTP
Network News Transfer Protocol is used to transport Usenet articles |
| 135 | RPC/DCOMscm
Remote Procedure Call is used to located DCOM ports request a service from a program on
another computer on the network |
| 137-139 | NetBIOS
is used to conduct name querying, sending of data, and other functions over a
NetBIOS connection |
| 143 | IMAP
Internet Message Access Protocol is used to receive email from a mail server with more
features than POP3 |
| 161 | SNMP
Simple Network Management Protocol is used to remotely monitor network devices |
| 162 | SNMPTRAP
Used to send Trap and InformRequests to the SNMP Manager on a network |
| 389 | LDAP
Lightweight Directory Access Protocol is used to maintain directories of users and other
objects |
| 443 | HTTPS
Hyper Text Transfer Protocol Secure is used to transmit web page data to a client over an
SSL/TLS-encrypted connection |
| 445 | SMB
Server Message Block is used to provide shared access to files and other resources on a
network |
| 465/587 | SMTP with SSL/TLS
Simple Mail Transfer Protocol used to send email over the Internet with an SSL and TLS
secured connection |
| 514 | Syslog
Syslog is used to conduct computer message logging, especially for routers and firewall logs |
| 636 | LDAP SSL/TLS
LDAP is used to maintain directories of users and other objects over an encrypted SSL/TLS
connection |
| 860 | iSCSI
iSCSI is used for linking data storage facilities over IP |
| 989/990 | FTPS
File Transfer Protocol Secure is used to transfer files from host to host over an encrypted
connection |
| 993 TCP | IMAP4 with SSL/TLS
Internet Message Access Protocol is used to receive email from a mail server over an SSL/TLSencrypted
connection |
| 995 | POP3 (SSL/TLS)
Post Office Protocol v3 is used to receive email from a mail server using an SSL/TLS-encrypted
connection |
| 1433 | Ms-sql-s
Microsoft SQL server is used to receive SQL database queries from clients |
| 1645/1646 | RADIUS (alternative)
Remote Authentication Dial-In User Service is used for authentication and authorization
(1645) and accounting (1646) |
| 1701 | L2TP
Layer 2 Tunnel Protocol is used as an underlying VPN protocol but has no inherent security |
| 1723 | PPTP
Point-to-Point Tunneling Protocol is an underlying VPN protocol with built-in security |
| 1812/1813 | RADIUS
Remote Authentication Dial-In User Service is used for authentication and authorization
(1812) and accounting (1813) |
| 3225 | FCIP
Fibre Channel IP is used to encapsulate Fibre Channel frames within TCP/IP packets |
| 3260 | iSCSI Target
iSCSI Target is as the listening port for iSCSI-targeted devices when linking data storage
facilities over IP |
| 3389 | RDP
Remote Desktop Protocol is used to remotely view and control other Windows systems via a
Graphical User Interface |
| 3868 | Diameter
A more advanced AAA protocol that is a replacement for RADIUS |
| 6514 | Syslog over TLS
It is used to conduct computer message logging, especially for routers and firewall logs, over
a TLS-encrypted connection |
| 53 | DNS
Domain Name Service is used to resolve hostnames to IPs and IPs to hostnames |
