Contents
Issue
Potential issue one may encounter, shortage of entropy available, e.g. to /dev/random device. That may cause issues such as programs needing entropy, such as cryptographic key generation, taking unacceptably long, or effectively stalling, and may cause some things to not function or not function acceptably. This may mostly or entirely happen in cases of (much) older Debian and kernels thereof, and/or may happen on certain hardware with limited capabilities.
Typical symptoms would be (extreme) slowness and/or stalling of programs and functionality as noted above, and often under use,
/proc/sys/kernel/random/entropy_avail
commonly showing low numbers (like only one or two digits), and generally (much) lower than that shown by:
/proc/sys/kernel/random/poolsize
One can often work around or fix the issue by installing at least one of the packages noted further below.
Packages
Commonly installing one of these packages noted below can well address the entropy one may encounter noted above. Installing the package haveged and/or rng-tools5 (or on older Debian rng-tools or alternatively on not so old Debian rng-tools-debian) are among the more common ways to address the issue.
Debian version |
Packages |
|||||||
Debian 13 |
haveged |
rng-tools-debian |
|
rng-tools5 |
ekeyd |
|
|
|
Debian 12 |
haveged |
rng-tools-debian |
|
rng-tools5 |
ekeyd |
|
|
|
Debian 11 |
haveged |
rng-tools-debian |
rng-tools |
rng-tools5 |
ekeyd |
randomsound |
|
|
Debian 10 |
haveged |
rng-tools-debian |
rng-tools |
rng-tools5 |
ekeyd |
randomsound |
|
yhsm-tools |
Debian 9 |
haveged |
|
rng-tools |
rng-tools5 |
ekeyd |
randomsound |
|
yhsm-tools |
Debian 8 |
haveged |
|
rng-tools |
|
ekeyd |
randomsound |
|
yhsm-tools |
Debian 7 |
haveged |
|
rng-tools |
|
ekeyd |
randomsound |
|
yhsm-tools |
Debian 6 |
|
|
rng-tools |
|
ekeyd |
randomsound |
|
|
References
Wikipedia: entropy
- Linux kernel documentation: