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ITP 457 Network Security

ITP 457 Network Security. Networking Technologies II UDP. Overview. UDP IP NAT. UDP. UDP – User Datagram Protocol Also member of TCP/IP TCP and UDP are cousins An application developer can choose to transmit data using either TCP or UDP

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ITP 457 Network Security

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  1. ITP 457Network Security Networking Technologies II UDP

  2. Overview • UDP • IP • NAT

  3. UDP • UDP – User Datagram Protocol • Also member of TCP/IP • TCP and UDP are cousins • An application developer can choose to transmit data using either TCP or UDP • Both protocols cannot be used simultaneously in an application

  4. UDP Characteristics • Connectionless – the protocol doesn’t know or remember the state of a connection • Does not have concept of • Session initiation • Acknowledgement • No error checking – does not retransmit lost packets nor does it put them in proper order

  5. UDP • UDP also called: “Unreliable Damn Protocol” • It is inherently unreliable • Unreliability is ok – IF it can buy you SPEED! • Some applications more interested in getting packets across the network and don’t need super high reliability. • Good protocol for a large number of connections

  6. UDP • Services that use UDP are • Streaming Video/ Audio • DNS queries • Online Games • Voice-over-IP (VoIP) • DHCP • DNS • SNMP • RIP

  7. UDP header UDP source port UDP destination port Message Length Checksum Data

  8. UDP Ports • UDP – 65,535 ports • Some typical ports: • 53 – DNS (Domain Name Server) • 67 – DHCP (Dynamic Host Control Protocol) • 69 – TFTP (Trivial File Transfer Protocol) • 161 – SNMP (Simple Network Management Protocol) • 514 – Syslog • 6112 – Battle.NET • 14567 – Battlefield 1492 • 26000 – Quake Server • 27015 – Halflife Server • For a searchable database of known ports: • http://www.ports-services.com/

  9. IS UDP less secure than TCP? • YES! • Absence of three-way handshake implies no Sequence numbers or no control bits. • Difficult for firewalls and routers to track where the ends systems are in their communications • We cannot completely turn off UDP, due to some of the necessary protocols that use UDP

  10. Port Scanning Lab!!!

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