T1043 Commonly Used Port

**This technique has been deprecated. Please use Non-Standard Port where appropriate.** Adversaries may communicate over a commonly used port to bypass firewalls or network detection systems and to blend with normal network activity to avoid more detailed inspection. They may use commonly open ports such as * TCP:80 (HTTP) * TCP:443 (HTTPS) * TCP:25 (SMTP) * TCP/UDP:53 (DNS) They may use the protocol associated with the port or a completely different protocol. For connections that occur internally within an enclave (such as those between a proxy or pivot node and other nodes), examples of common ports are * TCP/UDP:135 (RPC) * TCP/UDP:22 (SSH) * TCP/UDP:3389 (RDP)