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I have a Debian server with OpenSSH_6.7p1 installed and I use 4096 bits key to encrypt the communication. No matter I download or upload a file from/to a client (I tried WinSCP and Syncback and they are on the whole the same) in the same LAN, the speed is usually 1-2MB/S. Is this normal? (I guess it is not since my p2p download speed can be up to 20MB/S)
Mamsds
Posted 2016-10-31T16:04:38.363
Reputation: 137
0
Yes, it is normal. You are not using 4096 bits encryption key to encrypt the communication. It would be much slower, if it would be able to pass even something. You are using probably AES256 symmetric cipher, that is already accelerated in Intel processors (if not, provide verbose log which will tell you what are you using). You are using 4096 bit key for authentication, which is something completely different and it is done only once per connection!
It also depends on the version of the clients you are using. They might not accelerate the encryption, might use outdated ciphers or so. Comparing with p2p is very unfortunate (I don't think you run the p2p only from your server).
Jakuje
Posted 2016-10-31T16:04:38.363
Reputation: 7 981
It's a long shot but any chance you have a 10Mb/s network connection or WiFi link somewhere in the path? Or a lot of other network traffic on the server? – Andrew – 2016-10-31T16:10:45.877
Hi @Andrew no usually I am the only user of the wifi. Besides, the Debian server is using networking cable which should be much faster. – Mamsds – 2016-10-31T16:23:17.410
SFTP is CPU-intensive. Test a faster server to see if that is the bottleneck. – DrMoishe Pippik – 2016-10-31T17:04:16.900
Hi @DrMoishePippik, I am using a quad-core processor (to be specific, it is Intel(R) Core(TM) i7-4702MQ CPU @ 2.20GHz) and I only upload/download one file at a time. Therefore, I guess it should not be the cause of the problem. – Mamsds – 2016-10-31T17:11:13.870