I'm using the latest (20080914) UDPcast, which I compiled from source on Ubuntu 8.04 on x64 (xeon). I get the same results I describe here, when I use the ancient (2004) UDPCast available in the Ubuntu packaging system. I also get the same results I describe here, whether I use "--file" or >file. I am transmitting data about 51GB in size from one machine to several others; it is a database backup that I pipe from pg_dump with something like this: pg_dump yadayada | udp-sender --no-kbd --autostart 90 and I receive it on 3 other machines with this: udp-receiver --portbase 10200 --file filenamehere On the sender, the output ends like so: bytes= 54 682 988 148 re-xmits=0166670 ( 0.4%) slice=0032 73 709 551 615 - 2 Transfer complete. Disconnecting #0 (ip-address-redacted) Disconnecting #1 (ip-address-redacted) Disconnecting #2 (ip-address-redacted) On receiver 1, it ends like so: bytes= 54 682 988 148 (123.12 Mbps) 54 682 848 884 Transfer complete. the file is 54682848884 bytes long. On receiver 2, it ends like so: bytes= 54 682 988 148 (123.11 Mbps) 54 682 848 884 Transfer complete. the file is 54682848884 bytes long. On receiver 3, it ends like so: bytes= 54 682 988 148 (123.13 Mbps) 54 682 938 996 Transfer complete. the file is 54682938996 bytes long. On this particular run, I got "lucky" in that two of the 3 receivers got the same file length; most of the time, 3 receivers end up with files of 3 different lengths. I think the correct length is 54 682 988 148, meaning that 0 of the 3 got the file delivered correctly. In the output, udp-receiver appears to know both the correct length and the actual written length, yet not be bothered by them being different (!!). I find this quite surprising and rather disturbing... I had planned to wrap an md5 mechanism around UDPcast somehow as an end-to-end check of the contents, but it's pointless to do that if it doesn't even get the correct *length* of the data. Any help much appreciated, as I find UDPcast to be a fantastic idea and nicely implemented tool, aside from this problem. Could there be some issue in which udp-receiver is confused between what go to the file/stdout (data payload) vs to stderr (absolutely everything else) ? -- Kyle Cordes http://kylecordes.com