[Buildroot] SSH server starts too late

Andreas Ziegler br015 at umbiko.net
Fri Feb 21 12:51:18 UTC 2020


Hi Omar,

On 2020-02-21 13:00, Hammami Omar <omar18hammami at gmail.com> wrote
> I am using the buildroot version "2019.11.1" and I have noticed that my 
> SSH
> server starts too late.
> I was using an old version "2017.08" and the SSH server was starting
> normally.

This issue is not related to Buildroot, but caused by changes in 
libopenssl (which in turn is used by OpenSSH), starting around the 
middle of last year. You will find a lot of background information when 
you search the www for 'boot-time entropy starvation'; the cause is, 
reading random data from /dev/urandom blocks until the kernel entropy 
pool has been initialized.

Workarounds:

(a) Patch libopenssl (not recommended for nodes directly connected to 
the WAN).
(b) Use a more recent kernel; version 5.4.y introduced a temporary fix 
for this issue.
(c) Use other sources of extra randomness, as proposed by Peter 
Seiderer.

Kind regards,
Andreas


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