[CentOS] looking for ideas about how to create a constant data stream

Sat May 30 14:04:59 UTC 2020
Valeri Galtsev <galtsev at kicp.uchicago.edu>

On 5/30/20 5:46 AM, Anand Buddhdev wrote:
> On 30/05/2020 12:32, hw at gc-24.de wrote:
> Hi hw,
>> I'm looking for a good way to create a constant data stream that will 
>> occupy a
>> bandwidth of about 2--5Mbit/sec between two remote hosts over the 
>> internet.  I
>> have full access to the hosts involved.
>> My first attempt to use scp to copy data from /dev/null on host A to 
>> /dev/null
>> on host B, but scp says '/dev/null: not a regular file'.  If something 
>> like
>> that would work, I would be able to limit the bandwidth of this 
>> transfer in
>> the router(s) involved so that it won't occupy all the bandwidth.
> You can't read from /dev/null. You get nothing from it. You're better 
> off using /dev/random, for example. That will give you a continuous 
> stream of random bytes.

I would recommend to read from /dev/zero instead, it will give you a 
stream of zeroes. Using /dev/random is OK, but has one disadvantage in 
the OP case: you exhaust machine's accumulated entropy which may be more 
needed for other tasks (like ssh or ssl connections)...

Just my 2 cents.


> However, that's not the focus of this. You want a sustain a stream of 
> packets between two hosts. You're better off using UDP for this. And a 
> good tool for generating such packets would be "iperf". It can measure 
> bandwidth between two nodes more accurately.
> Regards,
> Anand
> _______________________________________________
> CentOS mailing list
> CentOS at centos.org
> https://lists.centos.org/mailman/listinfo/centos

Valeri Galtsev
Sr System Administrator
Department of Astronomy and Astrophysics
Kavli Institute for Cosmological Physics
University of Chicago
Phone: 773-702-4247