What ports should be closed?

The answer to this question depends on your specific security requirements and network configuration. In general, you should close ports that are not necessary for the normal operation of your system or network.

Here are some ports that are commonly recommended to be closed or filtered:

1. Port 23 (Telnet): Telnet is an insecure protocol that sends data in plaintext, making it vulnerable to interception and eavesdropping. It is recommended to use SSH instead.
2. Port 21 (FTP): FTP is also an insecure protocol that sends login credentials and data in plaintext. It is recommended to use SFTP or FTPS instead.
3. Port 25 (SMTP): SMTP is used for email transmission, and is often targeted by spammers and attackers. It is recommended to restrict SMTP traffic to authorized servers only.
4. Port 137-139 (NetBIOS): NetBIOS is an older protocol that is often used for file and printer sharing on Windows networks. It is vulnerable to attacks and should be filtered or disabled if not needed.
5. Port 445 (SMB): SMB is used for file sharing on Windows networks and is often targeted by attackers. It is recommended to filter or restrict SMB traffic to authorized users and servers only.

However, it’s important to note that closing ports can also impact the normal operation of your system or network. It’s recommended to consult with a security professional or IT expert to ensure that your security measures are appropriate for your specific needs.

Read More: How to Close Exposed High-Risk Ports