I'm currently using COPSSH to tunnel various connections to a remote Windows box and connecting using plink.exe from the PUTTY suite. After connecting directly, I've come to realise that the quality of connection using this setup is appalling. Tunnelled connections appear to get slower and slower. Can anyone recommend secure tunnel software that is more performant than my current setup?

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    Maybe low performance is due to network link speed/bandwidth. – lg. Jul 1 '10 at 14:05
  • That sentiment is why I've put up with this for over a year, however in an experiment, I opened up the ports directly and connected without tunneling. The speed difference is astonishing. – spender Jul 1 '10 at 14:30
  • performant is not a word – JamesRyan Jul 1 '10 at 15:22
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    @EK: "I don’t know why; it’s a perfectly cromulent word." en.wiktionary.org/wiki/performant – jscott Jul 1 '10 at 15:26
  • Also see serverfault.com/questions/57626/… and sites.inka.de/~W1011/devel/tcp-tcp.html. Basically any tunneling of TCP via TCP is going to result in worse performance. – Zoredache Jul 1 '10 at 16:47

I've used both stunnel, and the putty family of tools (plink, putty), and I've only rarely found performance issues. I would imagine your slowness comes from poor network connection, or performance issues on either end of the pipe.

  • After replacing "COPSSH" with "Kpym Telnet/SSH", all is good. – spender Jul 1 '10 at 16:20

A UDP-based protocol will be more asynchronous than serializing over a tcp stream.

This should give OpenVPN better performance than OpenSSH on a lossy or high-latency network.


Two options that come to mind are stunnel (if you want something lightweight) and OpenVPN. Either should work just fine in windows, though I've never used either outside of a Linux/BSD environment, so I can't help out with any gotchas, recommendations, etc.


Stunnel (although I've only used it for connection encryption on MSWindows - on Linux running a tunnelled network connection runs like a clock).

I've heard good things about openvpn.

Do you need a tunnelled connection? i.e. have you considered IPSEC?



I find that plink.exe has much higher latency than Cygwin's ssh on windows. The difference is quite noticeable when using Synergy to share a keyboard and mouse.

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    I switched from plink to openSSH because of latency issues. It dropped from 1 second to 100ms! – hplbsh Nov 20 '11 at 20:57

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