Slow uploads when using explicit over TLS/SSL

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Slow uploads when using explicit over TLS/SSL

I was comparing WinSCP 4.2.9 and FileZilla 3.3.4.1 upload transfers using an FTP over an explicit tls/ssl connection.
Of both clients, the settings are the same:

- Port 21
- Protocol: FTP + TLS Explicit Encryption (I also tried implicit and SSL)

I confirm that both clients switch to a secure channel via the AUTH TLS and PROT P commands.

However, WinSCP transfer rate to upload the same file is about 3 or 4 times slower than FileZilla. I did multiple tries, also tested implicit, explicit, passive, active... but same result. I also tried the winscp.com command-line version (which is what I really need), with same results.

Is there anything I'm missing?

Thank your very much!

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martin
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Re: Slow uploads when using explicit over TLS/SSL

Can you send me an email, so I can send you back a debug version of WinSCP to track the problem? Please include link back to this topic in your email. Also note in this topic that you have sent the email. Thanks.

You will find my address (if you log in) in my forum profile.
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resteban
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Re: Slow uploads when using explicit over TLS/SSL

martin wrote:

Can you send me an email, so I can send you back a debug version of WinSCP to track the problem? Please include link back to this topic in your email. Also note in this topic that you have sent the email. Thanks.

You will find my address (if you log in) in my forum profile.

Hello Martin,

I've just sent you the email.

Thanks!

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Aguest2
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speed limits

Over long distance (WAN) on a tuned system, WinSCP caps around 500kbytes** both upload and download.

** somewhere between 450 and 600. I don't have the exact number as we stopped using winscp fairly quickly in our testing. If this becomes critical, I can ask for access to the remote PC again to get you that number.


We found that switching to Filezilla removed the download cap, reaching up to 4.4MB/s (40mbps - which was near the limit of the line). Upload was capped at 650kbytes, which has since been removed by the Filezilla devs if you use nightly build version (10-26 verified).

Why am I here? Because I have a client that wants to script downloads, and WinSCP does that. :D


To replicate the problem: Use WinSCP over long distance (our ping was 80ms) to a Unix SFTP server, ideally one with Openssh (and possibly HPN patches), and at least 100mb ethernet connection. You will see that WinSCP hits a cap and doesn't go beyond it. Both upload and download are affected.

Thank you.

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martin
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Re: speed limits

Can you try it with WinSCP 4.3 beta?
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roger.e
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Exactly, that's the same issue we were having. FileZilla works great, but it doesn't support scripting.
Martin, I just tried 4.3 beta, but it seems there's a bug, as it gives me the following error when trying to connect to our server over an explicit TLS connection:

SSL_connect: error in SSLv3 read server hello B
Can't establish SSL connection
SSL_connect: error in SSLv3 read server hello B
Disconnected from server
Connection failed.
Proceed with negotiation.

I also tried all other SSL combinations, with the same result. I also got some "Invalid access to memory" errors...

Thanks

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martin
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roger.e wrote:

Exactly, that's the same issue we were having. FileZilla works great, but it doesn't support scripting.
Martin, I just tried 4.3 beta, but it seems there's a bug, as it gives me the following error when trying to connect to our server over an explicit TLS connection:

SSL_connect: error in SSLv3 read server hello B
Can't establish SSL connection
SSL_connect: error in SSLv3 read server hello B
Disconnected from server
Connection failed.
Proceed with negotiation.

I also tried all other SSL combinations, with the same result. I also got some "Invalid access to memory" errors...
Can you send me an email, so I can send you back a debug version of WinSCP to track the problem? Please include link back to this topic in your email. Also note in this topic that you have sent the email. Thanks.

You will find my address (if you log in) in my forum profile.
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Martin Prikryl

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Aguest2
Guest

Just to let you know, I will test this once my customer gives me access to a test PC again. Right now they removed my access and have completely stifled my attempts to assist them with their problems... I did try to install WinSCP 4.3 on my local laptop but ran into that "Invalid access to memory" error but thought that was related to my lack of admin rights on my laptop.

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Aguest2
Guest

tested

Turns out the person I was working with has left, so that's why I've been stuck in limbo. I worked today with a non technical user to get WinSCP 4.3 beta installed on her PC. Cursory testing appeared that speeds are improved. She told me she was seeing 1100 kib/s. Still slow but better than before (We can reach up to 4.4mb/s on that network). Her system's completely untuned, so I can't tell if its WinSCP or her system.

I also got a peek at their prod downloads. 74.6 KiB/s ??!! no wonder they are complaining.

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Guest

I can confirm this (WinSCP 4.2.9). Using scripting i get transfer speeds about 1/4 of what is normal. I checked against CuteFTPPRO and Filezilla. Connection is FTP with -explicitssl.

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Guest

Slow FTPS

Hello, any news on this? I'm also seeing this super-slow speed through ftps compared with other ftp clients like filezilla. I really like winscp, but this problem makes it unusable at the time of transferring big files. It's strange this bug can't be solved in an easy way. There must be some kind of buffer size limit set somewhere. Just guessing, but that's what it seems...

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aguest2
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nope

Finally got access back to the test PC at the remote site.

Result? Not fixed.

Details:
Filezilla results: Transfer of 600mb file in 3minutes (capping out at 4.4mb/s due to line limitations).


WinSCP 4.3.1 beta results: Transfer of the same 600mb file going to take about 14minutes. 689KiB/s

ps: WinSCP is using blowfish, Filezilla is using default, quite likely AES cipher which is the slower one.

Note: Going to see if I can change Filezilla to show me KiB/s instead of MB/s. But 4.4mb/s ends up around 4400KiB/s.

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aliengerm1
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FYI

I registered on the forums. I wrote the "Aguest2" posts above. This way you can send me an email if you want to work with me directly.

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martin
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Re: nope

aguest2 wrote:

ps: WinSCP is using blowfish, Filezilla is using default, quite likely AES cipher which is the slower one.
What protocol are you referring to? Looks like SSH (SCP or SFTP). While this thread is about FTPS.
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