UDP
User Datagram Protocol
Benutzer-Datagramm-Protokoll
UDP is a simple transport protocol that sends data without connection setup and without delivery guarantee — fast but „unsecured“. It is suitable for applications in which speed matters more than completeness, such as voice and video transmission, DNS or time synchronisation. It is the lean counterpart to Transmission Control Protocol (TCP).
History & facts. UDP forgoes connection setup, acknowledgements and retransmission; it simply sends datagrams off. This makes it fast and economical but unreliable in the technical sense — lost packets stay lost. Especially security-relevant is that the missing connection check facilitates forgery (spoofing) and amplification attacks: small forged requests can trigger large responses to a victim, a common means in Distributed Denial of Service (DDoS).
Outlook & recommendation. In defence, widespread UDP services (such as DNS or time services) deserve particular attention, since they can be misused for amplification attacks; securing them and filtering forged source addresses reduce the risk. In network observation and forensics, UDP traffic is just as revealing as Transmission Control Protocol (TCP) — here too, unusual destinations or volumes betray suspicious activity. As with TCP: confidentiality arises only through an overlying encryption.