I'm migrating our Icinga 2 from Debian 8 to Ubuntu 18.04. The old server had NRPE plugin 2.15. The new server has NRPE plugin 3.2.1.
If I try to connect with the new plugin to old NRPE servers (v2.15 too), I get these errors:
$ /usr/lib/nagios/plugins/check_nrpe -H some.server
CHECK_NRPE: (ssl_err != 5) Error - Could not complete SSL handshake with 1.2.3.4: 1
$ /usr/lib/nagios/plugins/check_nrpe -H some.server -n
CHECK_NRPE: Receive header underflow - only -1 bytes received (4 expected).
$ /usr/lib/nagios/plugins/check_nrpe -2 -H some.server
CHECK_NRPE: (ssl_err != 5) Error - Could not complete SSL handshake with 1.2.3.4: 1
$ /usr/lib/nagios/plugins/check_nrpe -2 -H some.server -n
CHECK_NRPE: Receive header underflow - only -1 bytes received (4 expected).
The NRPE server always logs this:
Error: Could not complete SSL handshake. 1
The KB entry says, this should work. How to make the new plugin work with the old NRPE servers?