ILO3 hardware monitoring stopped working after Debian upgrade due to outdated TLS protocols

Written by Claudio Kuenzler - 0 comments

Published on March 24th 2022 - last updated on July 11th 2024 - Listed in Hardware Monitoring SSL Security

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After a monitoring (satellite) server was upgraded from Debian 9 (Stretch) to 10 (Buster), the hardware monitoring of HP servers (using ILO3) stopped working.

The plugin used for monitoring the HP hardware health is check_ilo2_health, an excellent monitoring plugin created and maintained since 2007 by Alexander Greiner-Baer, which uses the ILO (Integrated Lights Out) management interface of HP servers.

ILO communication error with newer OpenSSL version

After the Debian distribution upgrade, the ILO hardware checks stopped working. On the command line the error could be reproduced:

root@buster:~# /usr/lib/nagios/plugins/check_ilo2_health.pl -H iloip -3 -u monitoring -p secret -a -c -d -o -W -t 60
ILO2_HEALTH UNKNOWN - ERROR: Failed to establish SSL connection with iloip:443  SSL connect attempt failed error:1425F102:SSL routines:ssl_choose_client_version:unsupported protocol.

The Debian upgrade from Stretch to Buster includes a major change in the OpenSSL version and its settings:

• Debian 9 comes with OpenSSL 1.1.0l
  
• Debian 10 comes with OpenSSL 1.1.1d

Bookworm with OpenSSL 3.0.x needs a different fix

The fix mentioned above works fine for Debian 10 (Buster) and 11 (Bullseye) but does not work for Debian 12 (Bookworm), which now has OpenSSL 3.0.x installed. Another workaround needs to be applied here.

First you can verify that the check_ilo2_health.pl can't establish a SSL connection:

root@bookworm:~# /usr/lib/nagios/plugins/check_ilo2_health.pl -H iloip -3 -u monitoring -p secret -a -c -d -o -W -t 60
ILO2_HEALTH UNKNOWN - ERROR: Failed to establish SSL connection with 192.168.11.11:443  SSL connect attempt failed error:0A000152:SSL routines::unsafe legacy renegotiation disabled.

Create a separate openssl.cnf configuration file (I'm using /usr/lib/nagios/plugins/openssl.cnf) with the following contents:

root@bookworm:~# cat /usr/lib/nagios/plugins/openssl.cnf
openssl_conf = openssl_init

[openssl_init]
ssl_conf = ssl_sect

[ssl_sect]
system_default = system_default_sect

[system_default_sect]
MinProtocol = TLSv1.0
Options = UnsafeLegacyRenegotiation
CipherString = DEFAULT@SECLEVEL=0

Tell the systen to use this SSL config in your Shell session by setting the OPENSSL_CONF environment variable:

root@bookworm:~# export OPENSSL_CONF=/usr/lib/nagios/plugins/openssl.cnf

From the OpenSSL documentation:

OPENSSL_CONF
    The path to the config file. Ignored in set-user-ID and set-group-ID programs.

Now the plugin works again:

root@bookworm:~# /usr/lib/nagios/plugins/check_ilo2_health.pl -H iloip -3 -u monitoring -p secret -a -c -d -o -W -t 60
ILO2_HEALTH OK - (Board-Version: ILO>=3) Power Usage: 214 Watts, Temperatures: Temp_1 (OK): 24, Temp_2 (OK): 40, Temp_3 (OK): 40, Temp_4 (OK): 40, Temp_5 (OK): 43, Temp_6 (OK): 47, Temp_7 (OK): 48, Temp_8 (OK): 53, Temp_9 (OK): 46, Temp_10 (OK): 52, Temp_11 (OK): 43, Temp_12 (OK): 52, Temp_19 (OK): 29, Temp_20 (OK): 37, Temp_21 (OK): 37, Temp_22 (OK): 35, Temp_23 (OK): 46, Temp_24 (OK): 44, Temp_25 (OK): 42, Temp_26 (OK): 44, Temp_30 (OK): 77 | power=214;; Temp_1=24;41;45 Temp_2=40;82;83 Temp_3=40;82;83 Temp_4=40;87;92 Temp_5=43;87;92 Temp_6=47;87;92 Temp_7=48;87;92 Temp_8=53;90;95 Temp_9=46;65;70 Temp_10=52;90;95 Temp_11=43;70;75 Temp_12=52;90;95 Temp_19=29;70;75 Temp_20=37;70;75 Temp_21=37;80;85 Temp_22=35;80;85 Temp_23=46;77;82 Temp_24=44;70;75 Temp_25=42;70;75 Temp_26=44;70;75 Temp_30=77;110;115

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