TCP 445 vs TCP 139

TCP 445 and TCP 139 are both ports used for file sharing and network services in Windows environments, but they operate in different contexts.

TCP 139 (NetBIOS Session Service)

• Protocol: NetBIOS over TCP/IP.
• Usage: Primarily used for file and printer sharing in older Windows systems. It relies on the NetBIOS protocol, which allows applications on separate computers to communicate over a local area network (LAN).
• Connection Type: Connection-oriented, allowing for sessions between computers.

TCP 445 (SMB over TCP)

• Protocol: Server Message Block (SMB) protocol directly over TCP/IP.
• Usage: Used for file sharing, printer sharing, and various network services. SMB over TCP allows for a more efficient and straightforward communication method without needing NetBIOS.
• Connection Type: Directly handles SMB requests without relying on NetBIOS, which can improve performance and reduce overhead.

Key Differences

• Dependence: TCP 139 relies on NetBIOS, while TCP 445 does not. This makes TCP 445 more modern and efficient.
• Compatibility: TCP 139 is mainly used for compatibility with older systems, whereas TCP 445 is more common in current Windows networking setups.
• Performance: TCP 445 generally offers better performance because it removes the overhead associated with NetBIOS.

In modern environments, TCP 445 is preferred, while TCP 139 is often disabled for security reasons, as it can expose systems to vulnerabilities.