Apparently rngd-service fails by default:

# systemctl daemon-reload
# systemctl restart rngd
# systemctl status rngd
x rngd.service - Start entropy gathering daemon (rngd)
      Loaded: loaded (/lib/systemd/system/rngd.service; enabled; preset: enabled)
      Active: failed (Result: exit-code) since Mon 2022-08-15 14:46:07 CEST; 8s ago
    Duration: 3ms
        Docs: man:rngd(8)
     Process: 16819 ExecStart=/usr/sbin/rngd -f (code=exited, status=1/FAILURE)
    Main PID: 16819 (code=exited, status=1/FAILURE)
         CPU: 2ms

Aug 15 14:46:07 dpcl064 systemd[1]: Started Start entropy gathering daemon (rngd).
Aug 15 14:46:07 dpcl064 rngd[16819]: Unable to open file: /dev/tpm0
Aug 15 14:46:07 dpcl064 rngd[16819]: can't open any entropy source
Aug 15 14:46:07 dpcl064 rngd[16819]: Maybe RNG device modules are not loaded
Aug 15 14:46:07 dpcl064 systemd[1]: rngd.service: Main process exited, code=exited, status=1/FAILURE
Aug 15 14:46:07 dpcl064 systemd[1]: rngd.service: Failed with result 'exit-code'.


# modprobe rng-core
# systemctl restart rngd
# systemctl status rngd
* rngd.service - Start entropy gathering daemon (rngd)
      Loaded: loaded (/lib/systemd/system/rngd.service; enabled; preset: enabled)
      Active: inactive (dead) since Mon 2022-08-15 14:53:10 CEST; 22s ago
    Duration: 4ms
        Docs: man:rngd(8)
     Process: 16889 ExecStart=/usr/sbin/rngd -f (code=exited, status=0/SUCCESS)
    Main PID: 16889 (code=exited, status=0/SUCCESS)
         CPU: 3ms

Aug 15 14:53:10 dpcl064 rngd[16889]: read error
Aug 15 14:53:10 dpcl064 rngd[16889]: read error
Aug 15 14:53:10 dpcl064 rngd[16889]: read error
Aug 15 14:53:10 dpcl064 rngd[16889]: read error
Aug 15 14:53:10 dpcl064 rngd[16889]: read error
Aug 15 14:53:10 dpcl064 rngd[16889]: read error
Aug 15 14:53:10 dpcl064 rngd[16889]: read error
Aug 15 14:53:10 dpcl064 rngd[16889]: read error
Aug 15 14:53:10 dpcl064 rngd[16889]: No entropy sources working, exiting rngd
Aug 15 14:53:10 dpcl064 systemd[1]: rngd.service: Deactivated successfully.


# modprobe intel-rng
modprobe: ERROR: could not insert 'intel_rng': No such device

# lscpu
Architecture:            x86_64
   CPU op-mode(s):        32-bit, 64-bit
   Address sizes:         36 bits physical, 48 bits virtual
   Byte Order:            Little Endian
CPU(s):                  4
   On-line CPU(s) list:   0-3
Vendor ID:               GenuineIntel
   BIOS Vendor ID:        Intel
   Model name:            Intel(R) Core(TM) i5 CPU         661  @ 3.33GHz
     BIOS Model name:     Intel(R) Core(TM) i5 CPU 661 @ 3.33GHz               To Be Filled By O.E.M. CPU @ 3.3GHz
     BIOS CPU family:     205
     CPU family:          6
     Model:               37
     Thread(s) per core:  2
     Core(s) per socket:  2
     Socket(s):           1
     Stepping:            2
     Frequency boost:     enabled
     CPU(s) scaling MHz:  37%
     CPU max MHz:         3334.0000
     CPU min MHz:         1200.0000
     BogoMIPS:            6687.80
     Flags:               fpu vme de pse tsc msr pae mce cx8 apic sep mtrr pge mca cmov pat pse36 clflush dts acpi mmx fxsr sse sse2 ht tm pbe syscall nx rdtscp lm constant_tsc arch_perfmon pebs bts rep_good nopl xtopolog
                          y nonstop_tsc cpuid aperfmperf pni pclmulqdq dtes64 monitor ds_cpl vmx est tm2 ssse3 cx16 xtpr pdcm sse4_1 sse4_2 popcnt aes lahf_lm pti ssbd ibrs ibpb stibp tpr_shadow vnmi flexpriority ept vpid
                           dtherm ida arat flush_l1d
Virtualization features:
   Virtualization:        VT-x
Caches (sum of all):
   L1d:                   64 KiB (2 instances)
   L1i:                   64 KiB (2 instances)
   L2:                    512 KiB (2 instances)
   L3:                    4 MiB (1 instance)
NUMA:
   NUMA node(s):          1
   NUMA node0 CPU(s):     0-3
Vulnerabilities:
   Itlb multihit:         KVM: Mitigation: VMX disabled
   L1tf:                  Mitigation; PTE Inversion; VMX conditional cache flushes, SMT vulnerable
   Mds:                   Vulnerable: Clear CPU buffers attempted, no microcode; SMT vulnerable
   Meltdown:              Mitigation; PTI
   Mmio stale data:       Not affected
   Retbleed:              Not affected
   Spec store bypass:     Mitigation; Speculative Store Bypass disabled via prctl
   Spectre v1:            Mitigation; usercopy/swapgs barriers and __user pointer sanitization
   Spectre v2:            Mitigation; Retpolines, IBPB conditional, IBRS_FW, STIBP conditional, RSB filling
   Srbds:                 Not affected
   Tsx async abort:       Not affected


The traditional workaround was something like

	# echo "HRNGDEVICE=/dev/urandom" >> /etc/default/rng-tools

Moving to rng-tools5 this config file is gone, AFAICS. rngd(8) doesn't help.



Regards

Harri

If you were doing that you were defeating the purpose of the program. If
you have no entropy sources for rngd, the best approach would be to
remove the program; failing to start is its correct behavior.

The software is not relevant for most systems these days.

Dear submitter,

as the package rng-tools5 has just been removed from the Debian archive
unstable we hereby close the associated bug reports.  We are sorry
that we couldn't deal with your issue properly.

For details on the removal, please see https://bugs.debian.org/1142760

The version of this package that was in Debian prior to this removal
can still be found using https://snapshot.debian.org/.

Please note that the changes have been done on the master archive and
will not propagate to any mirrors until the next dinstall run at the
earliest.

This message was generated automatically; if you believe that there is
a problem with it please contact the archive administrators by mailing
ftpmaster@ftp-master.debian.org.

Debian distribution maintenance software
pp.
Thorsten Alteholz (the ftpmaster behind the curtain)