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kritop
Asked: 2010-04-01 07:40:48 +0800 CST

Host timeout during file upload/download over SFTP/SSH

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I've tried different clients because I thought it was client related. All of them eventually disconnect, or stop transferring files - followed by getting a timeout disconnect. After a reconnect it works again for a bit of time. It is really strange, I can not figure out the reason.

I'm on a Mac, and the server is a VPS running Debian. If you need further information, please ask!

I appreciate any tips, because I'm kinda stuck!

linux debian ssh sftp

4 Answers

  1. Try running tcpdump at both ends and analyze the results in Wireshark. You should see which packets get stopped and retransmitted: that will help you to debug it.

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  2. Wireshark will give you a "bandwidth graph". Here is an old example from Ethereal days:

    alt text

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  3. What is the network like between the mac and server? Is it possible you are having an MTU (transmission unit problem), that is, you are sending a packet that is to big? This can happen with some DSL providers.

    • Greg
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  4. What does ssh -vvv produce when you try to connect to the remote server ? And what are the results of traceroute and ping to your server ?

    On the VPS server you could install something like Smokeping to see whether the connection of the server to your IP experiences intermittent problems.

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