Why is scp so slow

Share More Cancel. So, I'm curious, has anyone tried it? All Rights Reserved. If a shell on the remote side prints out anything for non-interactive sessions, your local scp process will happily interpret that output as SCP commands. At best, this will break the SCP protocol with obscure errors. At worst, the remote shell startup script is malicious and sends you an exploit payload instead of the file you wanted. And what about implementation bugs? These vulnerabilities are a good lesson for anyone building networked CLI applications.

Every other week we'll send a newsletter with the latest cybersecurity news and Teleport updates. Okay, so maybe SCP has some problems after all. How should we move the files around our computers without setting up a brand new system or resorting to snail-mailing USB drives?

It can give you a custom interactive prompt for exploring the remote filesystem or you can script with a pre-written series of commands. Rsync is another good alternative. Rsync is all about performance - it does a lot of complex computation locally to send as little data as possible over the network. Technically, it does data synchronization instead of pure transfer - if remote and local content are similar, only the deltas will be sent.

Again, it comes with its own downsides: the sender uses a lot of CPU power to figure out what to send and the receiver uses a lot of disk IO to put things together in the right order.

Rsync also does not come pre-installed on most systems, unlike OpenSSH. You exchange short, readable codes out-of-band like over the phone and throw in some files. The whole system is designed to be used by humans, if you need to transfer data between your laptop and some servers, Magic Wormhole is not the right tool.

Two great examples are Syncthing and Perkeep. Active 2 years, 1 month ago. Viewed 39k times. Improve this question. Jeff Loughlin. Jeff Loughlin Jeff Loughlin 1 1 gold badge 1 1 silver badge 5 5 bronze badges. It seems a network related problem. Try to transfer a test file say 1GB preferably with another protocol and measure transfer speed. I did that with iperf , which shows a 20Mbps throughput - about what you'd expect over an That is pretty slow for writes on the destination drive, even for a single sata spindle.

Add a comment. Active Oldest Votes. Copying large files over network , faster If you want to use scp anyway , then you should use traceroute and tcpdump and iftop to see the packets from source to destination.

Improve this answer. Community Bot 1. Fair enough. But this backup script has been running for years using scp, and completing in a day and a half which is perfectly acceptable to me, as it's just an unattended backup job that runs in the background once a month.

I'm looking for tools to diagnose what the bottleneck is, because something seems to have changed. Disable connection optimization dramatically improved performance for me. Optimize Connection. How do you access these settings?

When I open my settings panel it doesn't have this sub-cat??? I discovered for me, I was using a Proxy config to tunnel through a bastion host with plink.

I converted that to use the built in Tunnel config and that sped up throughput immensely. Did nothing for me. I've struggled with slow speeds from my ESXi servers for years. I just thought that there was something going on with those servers that caused the slow speeds. I appreciate the great product that the developers put out, but it sure seems like maybe this setting should be off by default since it impacts so many different people. JimBurd wrote: I appreciate the great product that the developers put out, but it sure seems like maybe this setting should be off by default since it impacts so many different people.

Hello, I have a relatively fast freenas server connected via 10G with my PC. When transfering a big systembackup file towards the NAS I noticed that the transfer rate was only about gbit. I did at expect something like three to four times that. No doubt that that was related to winscp …..

So there seems to be "some" room for improvement: - starting with migratio to 64 bit - and using multiple threads I understand that you are using standard librarys …… but never the less I hope that you can improve things.