News! (Sorry for the spam, but this problem turns to be a headache) The problem actually comes from ByteStrings (either lazy or strict). I reduced my server code to this: import Network import System.IO import qualified Data.ByteString(.Lazy) as L main = do (hdl,_,_) <- listenOn (PortNumber 7777) >>= accept hSetBuffering hdl NoBuffering inp <- L.hGetContents hdl putStrLn . show $ L.take 8 inp My client hasn't changed, and sends properly the data. So the server shouldn't hold. Well, even when trying to rawly print the first 8 bytes of the stream, it does. But when I use normal Strings, it doesn't hold: import Network import System.IO main = do (hdl,_,_) <- listenOn (PortNumber 7777) >>= accept hSetBuffering hdl NoBuffering inp <- hGetContents hdl putStrLn . show $ take 8 inp I think this behavior is normal for strict ByteStrings, but not for lazy ones... ----- Yves Parès Live long and prosper -- View this message in context: http://old.nabble.com/Network%3A-buffering-troubles-tp28162932p28166941.html Sent from the Haskell - Haskell-Cafe mailing list archive at Nabble.com.