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In an application (voip rtp media server), netstat -na on the server (172.16.226.3 bound to udp port 1286) gives the following line :
udp 0 0 172.16.226.3:1286 172.25.14.11:10000 ESTABLISHED
As an udp connection can not be really "established", it strikes me to see such a line. netstat documentation says that this field is used for tcp connection states, but I am sure that this really is an udp network flow. So : what does it means ? I know (wireshark dump) that my server sends back udp packets from 173.16.226.3:1286 to 172.25.14.11:10000, but I don't see why it should matter...
Os is debian 6.
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“ESTABLISHED” means there's an actual connection between your machine and the remote IP and port that is able to exchange traffic. Occasionally, you'll see “CLOSE_WAIT” in this column, which is a state TCP goes into while ending an established connection.
State – Indicates the state of a TCP connection. The possible states are as follows: CLOSE_WAIT, CLOSED, ESTABLISHED, FIN_WAIT_1, FIN_WAIT_2, LAST_ACK, LISTEN, SYN_RECEIVED, SYN_SEND, and TIME_WAIT. For more information about the states of a TCP connection, see RFC 793.
netstat displays incoming and outgoing network connections (TCP and UDP), host computer routing table information, and interface statistics.
It means that a program or service has bound to that port and is listening for incoming traffic.
A UDP socket can be connected via the connect(2) system call, so that the socket will only accept packets from the named peer.
I expect this is the source of the ESTABLISHED column.
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