[CentOS] Any way to reduce CPU use of OpenSSH?

Florin Andrei florin at andrei.myip.org
Mon Dec 15 22:53:52 UTC 2008

Steve Snyder wrote:
> On my CentOS v5.2 server (dual Pentium4) the OpenSSH daemon stands out 
> as being the most CPU-intensive of the

Wow, you must be sending terabytes of stuff through ssh. :-)

Assuming the request is legit:

1. Disable compression if you don't need it.

2. Try another crypto protocol. Years ago, when this problem was real 
:-) (sorry, no offense), I used to force blowfish instead of whatever 
crypto was default back then, and it produced a significant decrease of 
CPU usage on those Pentium II processors.

ssh -c blowfish-cbc hostname

I don't know which protocol is fastest nowadays, but I guess you can do 
a quick test and find out.

There might be some security implications for using a different crypto 
protocol, but you need to figure that out yourself.

Florin Andrei


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