Slow sFTP Transfer Speed with SSH Connection (SSH2)
When using FileZille, SSH Secure Shell client, CoreFTP, PSFTP and other secure FTP clients to transfer files between computers or servers, the transfer (upload and download) speed can be very slow compared with the speed achievable by FTP connection even though there is enough fast bandwidth on network and routers.
Compare with FTP which transfer speeds can easily go up to a few or tens of MB/s or GB/s, transferring files with sFTP connection typically lands you at around 30 – 60 KB/s. The main reason for the reduced transmitting speed is due to the fact that SSH, or SSH2 (which both sFTP and SCP depend on) has protocol implementation and encryption overhead that based on the amount of CPU processor and memory (used in internal flow control buffers) resources given to that transfer session. The buffers and limited availability of resources often end up become a bottleneck for network throughput of sFTP and SCP, especially on long and high bandwidth network links.
If you only able to transfer at a ridiculous low speed of tens of KB/s, try to download and use WinSCP. Once installed, establish a connection session to remote machine or computer by using the following settings and options:
File Protocol: SCP or sFTP with Allow SCP fallback ticked
SSH Encryption cipher selection policy: Move Blowfish to the first priority slot
With this setting, it’s possible to get transfer speed numerous times higher than when using sFTP over SSH2 connection. However, it’s still slow if comparing with unencrypted and unprotected FTP transfer. If you don’t mind about security, FTP is the best choice.
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September 24th, 2009 22:25
I have to say, SSH was the best thing they ever came out with. You can’t beat its security nor its reliabilty.
May 16th, 2009 04:12
There is great difference in what software you are using. I have whitnessed these same speeds with psftp, filezilla and winscp. But with openssh-based software (sftp) the speeds have been a LOT faster (~30MB/s) in local network. The reason for this might be that in my knowledge some windows software use psftp (putty) as their backend, and if there is problem in putty, this will affect all software that uses it.
June 18th, 2008 23:06
Unfortunately, I still get the same speed, about 60% of my actual upload speed
May 5th, 2008 23:10
You can also use FTPS to protect the control channel and leave the data channel unencrypted (which means full ftp speeds but the username/pass is protected). Watch out for firewalls though; FTPS is rather unloved by them
April 15th, 2008 15:06
Ohhh. Well, that explains it.