Differences for page UDPCurrent version compared with version Sun May 30 08:45:18 GMT 2004...
The UDP protocol is very similar to the [IP] itself, because it's just able to send datagrams from an host to another, without
to try to make the link reliable. As [IP], [UDP] datagrams can get lost, duplicated, or delivered out of order. Protocols using [UDP] that need
to be reliable have to implement retrasmission after a timeout on top of [UDP]. For instance the [DNS] protocol, that implements a request/reply
- protocol on top of [UDP] retry to sent the query after some time if no response was received from the [DNS] server.
+ protocol on top of [UDP] retry to send the query after some time if no response was received from the [DNS] server.
The main abstraction that [UDP] adds to [IP] is the concept of [port]. With [IP address]es it's possible to send data to a specific host,
- but with [port]s it's possible to send a data to a specific process of a specific host.
+ but with [port]s it's possible to send data to a specific process of a specific host.
+ ===UDP header===
+ [img udp-hdr.png]
+
+ This is the C structure for the UDP header:
+
+ struct udphdr {
+ __u16 source;
+ __u16 dest;
+ __u16 len;
+ __u16 check;
+ };
+
===IP spoofing and UDP===
Being [UDP] a datagram protocol there is no state, different UDP packets are not about the same connection.
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