Vulnerabilities
Port vulnerability remains a major weakness in conventional TCP/IP networks. Any given host can have up to 65,535 TCP and UDP ports. There are 1024 commonly used for well-known services, such as FTP, SSH, HTTP, SMTP, DNS, etc. The vulnerabilities include DoS attacks, penetration and protocol exploits. Open ports are actively used by port listeners. Ports can be closed, but not secured against malicious software as backdoors.