Insecure and Secure Ports

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Insecure Ports

• 21 FTP: File Transfer Protocol (FTP) sends the username and password from the client to the server.


• 23 TELNET: All information to and from the host on a Telnet connection is sent in plaintext and can be intercepted by an attacker.


• 25 SMTP: Simple Mail Transfer Protocol (SMTP) is the default for sending email messages. Since it is unencrypted, data contained within the emails could be discovered by network sniffing.


• 37 TIME: Time Protocol may be in use by legacy equipment and has mostly been replaced by using port 123 for Network Time Protocol (NTP).


• 53 DNS: Domain Name Service (DNS) is still widely used.


• 80 HTTP: Hyper Text Transfer Protocol (HTTP) is the basis of nearly all web browser traffic on the internet. Information sent via HTTP is not encrypted and is susceptible to sniffing attacks.


• 143 IMAP: Internet Message Access Protocol (IMAP) is a protocol used for retrieving emails. IMAP traffic on port 143 is not encrypted and is susceptible to network sniffing.


• 445 SMB: Server Message Block (SMB) is used by many versions of Windows for accessing files over the network. Files are transmitted unencrypted.


• 389 (LDAP): Lightweight Directory Access Protocol (LDAP) is used to communicate directory information from servers to clients. Since LDAP is not encrypted, it is susceptible to sniffing and manipulation attacks.

Secure Ports

• 22 SFTP: Uses encryption to protect user credentials and data packets being transferred.


• 22 SECURE SHELL: Secure Shell (SSH) on port 22 uses encryption to ensure that traffic between the host and terminal is not sent in plaintext format.


• 587 SMTP: The secure alternative is to use port 587 for SMTP using Transport Layer Security (TLS), which will encrypt the data between the mail client and the mail server.


• 123 NTP: NTP on port 123 offers better error-handling capabilities, reducing the likelihood of unexpected errors.


• 853 DoT: However, using DNS over TLS (DoT) on port 853 protects DNS information from being modified in transit.


• 443 HTTPS: HTTPS using TLS encryption is preferred, as it protects the data in transit between the server and the browser.


• 993 IMAP: The secure alternative is to use port 993 for IMAP, which adds SSL/TLS security to encrypt the data between the mail client and the mail server.


• 2049 NFS: Network File System (NFS). Although NFS can use encryption, it is recommended that NFS not be allowed through firewalls.


• 636 LDAPS: Lightweight Directory Access Protocol Secure (LDAPS) adds SSL/TLS security to protect information while it is in transit.