udp client: destination port unreachable question

Hello,

I used "trivial" UDPClient / Server example to send datagrams from one local interface (eth1) on my Linux box to Datagram server on yhe host not included into local routing table and I tried to capture outgoing udp traffic on interface eth1. I've got IOException

"ICMP: destination unreachable" and I only could capture outgoing

packets on loopback interface ( with Ethereal). Can someone help to

resolve my confusion: I thought UDP is "connectionless", e.g. will be

sent regardless. What does ICMP have to do with it and why does this

traffic appear on loopback interface?

Thank you,

[641 byte] By [vl_a] at [2007-11-27 6:13:35]