I’ve read through the responses and thought that you got a pretty raw deal. Firstly, the ACK is done at the TCP/IP stack level, not by client software. Happy to be corrected on this.

Also, rule out CPU overhead because the command line version is fast and therefore SSH (i.e. the CPU time required for compression) isn’t a problem. Also, to backup my claim, when I transferred a 600 MB file, the idle time on both client and server remained above 90%. CPU time is not the problem.

Just as a comparison, my 600 MB file took 10 minutes to transfer which , by my calculations, is 1 MB/sec which is 8 Mbits/sec, very slow.

The last piece to the puzzle is that all network communications to the box slow down when I’m transferring the file through Nautilus using SSH/SFTP. I think that I’m going to run a packet sniffer on the network to see what’s being sent, more to the point, what’s taking up the bandwidth.

It’s GOTTA be the acks that are slowing this thing down. No amount of CPU overhead on a P4 2GHz (I forget the bus speed) can account for an almost 90% performance loss.

Network tuning (send and receive buffers) would help SMB.

SFTP is poorly implemented in many places.

TLS/FTP is pretty good, all things considered.

I recommend TLS over http://FTP. It’s still not as fast as ftp, but it’s as close as you can get with encryption.

vsftpd supports TLS. I use filezilla (from sourceforge) for winders client.

With FTP, for instance, the CPU has very little to do. The data is not converted in anyway. It’s simply crammed into packets and shipped across the network. With SSH it has to be encrypted on one end and then decrypted on the other, and, unfortunately, that’s a lot of math. So, your CPU will be VERY involved with an SSH transaction. Now, if you use SFTP over SSH, you have to deal with an SSH subsystem and any of the sillyness involved there…. and it just gets dirtier and dirtier.

As far as why nautilus SSH would be slower than command line SSH more than likely has to do with packet size and any extra CPU being sucked out by whatever fancy dialog box the GUI is trying to show you. Nautilus isn’t know for speed.

What I’m trying to say is, your network and your disks are probably NOT your bottleneck. CPU is playing a large role here.

At work about a year ago they pushed out a requirement to use encryption for all data travelling over the intranet, even if it isn’t destined to leave our network. We saw a HUGE slow down from almost EVERY application… even though they are all written in different languages, on different platforms, with different purposes.

Oh, and… um… Yeah. Your mama.

And, as far as my mother is concerned, she did usually have a shot or two before walking out the door of The Plantation, but, who can discredit her for that?