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CHECK_NRPE: Error - Could not complete SSL handshake.

Posted: Tue Aug 29, 2017 7:34 am
by raamardhani7
Hi Team,

Please help me to solve below problem,

"CHECK_NRPE: Error - Could not complete SSL handshake."

Here i posted all server related docs:

Related to Nagios Server:

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[nagios@NagiosServer libexec]$ ./check_nrpe -H RemoteServer
CHECK_NRPE: Error - Could not complete SSL handshake.
[nagios@NagiosServer libexec]$

[nagios@NagiosServer libexec]$ ./check_nrpe -H RemoteServer -n
CHECK_NRPE: Error receiving data from daemon.
[nagios@NagiosServer libexec]$
Telnet command

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[nagios@NagiosServer ~]$ telnet RemoteServer 5666
Trying 10.10.10.30...
Connected to RemoteServer.
Escape character is '^]'.
Connection closed by foreign host.
[nagios@NagiosServer ~]$
Related to Remote server:
vi /etc/xinetd.d/nrpe

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service nrpe
{
        flags           = REUSE
        socket_type     = stream
        port            = 5666
        wait            = no
        user            = nagios
        group           = nagios
        server          = /usr/local/nagios/bin/nrpe
        server_args     = -c /usr/local/nagios/etc/nrpe.cfg --inetd
        log_on_failure  += USERID
        disable         = no
        only_from       = 127.0.0.1 10.10.10.10
}
where, 10.10.10.10 is Nagios server IP

vi /usr/local/nagios/etc/nrpe.cfg

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#############################################################################
# Sample NRPE Config File
# Written by: Ethan Galstad ([email protected])
#
# Last Modified: 11-23-2007
#
# NOTES:
# This is a sample configuration file for the NRPE daemon.  It needs to be
# located on the remote host that is running the NRPE daemon, not the host
# from which the check_nrpe client is being executed.
#############################################################################


# LOG FACILITY
# The syslog facility that should be used for logging purposes.

log_facility=daemon



# PID FILE
# The name of the file in which the NRPE daemon should write it's process ID
# number.  The file is only written if the NRPE daemon is started by the root
# user and is running in standalone mode.

pid_file=/var/run/nrpe.pid



# PORT NUMBER
# Port number we should wait for connections on.
# NOTE: This must be a non-priviledged port (i.e. > 1024).
# NOTE: This option is ignored if NRPE is running under either inetd or xinetd

server_port=5666



# SERVER ADDRESS
# Address that nrpe should bind to in case there are more than one interface
# and you do not want nrpe to bind on all interfaces.
# NOTE: This option is ignored if NRPE is running under either inetd or xinetd
#server_address=127.0.0.1



# NRPE USER
# This determines the effective user that the NRPE daemon should run as.
# You can either supply a username or a UID.
#
# NOTE: This option is ignored if NRPE is running under either inetd or xinetd

nrpe_user=nagios



# NRPE GROUP
# This determines the effective group that the NRPE daemon should run as.
# You can either supply a group name or a GID.
#
# NOTE: This option is ignored if NRPE is running under either inetd or xinetd

nrpe_group=nagios



# ALLOWED HOST ADDRESSES
# This is an optional comma-delimited list of IP address or hostnames
# that are allowed to talk to the NRPE daemon. Network addresses with a bit mask
# (i.e. 192.168.1.0/24) are also supported. Hostname wildcards are not currently
# supported.
#
# Note: The daemon only does rudimentary checking of the client's IP
# address.  I would highly recommend adding entries in your /etc/hosts.allow
# file to allow only the specified host to connect to the port
# you are running this daemon on.
#
# NOTE: This option is ignored if NRPE is running under either inetd or xinetd

allowed_hosts=127.0.0.1,10.10.10.10,10.10.10.20



# COMMAND ARGUMENT PROCESSING
# This option determines whether or not the NRPE daemon will allow clients
# to specify arguments to commands that are executed.  This option only works
# if the daemon was configured with the --enable-command-args configure script
# option.
#
# *** ENABLING THIS OPTION IS A SECURITY RISK! ***
# Read the SECURITY file for information on some of the security implications
# of enabling this variable.
#
# Values: 0=do not allow arguments, 1=allow command arguments

dont_blame_nrpe=1



# BASH COMMAND SUBTITUTION
# This option determines whether or not the NRPE daemon will allow clients
# to specify arguments that contain bash command substitutions of the form
# $(...).  This option only works if the daemon was configured with both
# the --enable-command-args and --enable-bash-command-substitution configure
# script options.
#
# *** ENABLING THIS OPTION IS A HIGH SECURITY RISK! ***
# Read the SECURITY file for information on some of the security implications
# of enabling this variable.
#
# Values: 0=do not allow bash command substitutions,
#         1=allow bash command substitutions

allow_bash_command_substitution=0



# COMMAND PREFIX
# This option allows you to prefix all commands with a user-defined string.
# A space is automatically added between the specified prefix string and the
# command line from the command definition.
#
# *** THIS EXAMPLE MAY POSE A POTENTIAL SECURITY RISK, SO USE WITH CAUTION! ***
# Usage scenario:
# Execute restricted commmands using sudo.  For this to work, you need to add
# the nagios user to your /etc/sudoers.  An example entry for alllowing
# execution of the plugins from might be:
#
# nagios          ALL=(ALL) NOPASSWD: /usr/lib/nagios/plugins/
#
# This lets the nagios user run all commands in that directory (and only them)
# without asking for a password.  If you do this, make sure you don't give
# random users write access to that directory or its contents!

# command_prefix=/usr/bin/sudo



# DEBUGGING OPTION
# This option determines whether or not debugging messages are logged to the
# syslog facility.
# Values: 0=debugging off, 1=debugging on

debug=0



# COMMAND TIMEOUT
# This specifies the maximum number of seconds that the NRPE daemon will
# allow plugins to finish executing before killing them off.

command_timeout=60



# CONNECTION TIMEOUT
# This specifies the maximum number of seconds that the NRPE daemon will
# wait for a connection to be established before exiting. This is sometimes
# seen where a network problem stops the SSL being established even though
# all network sessions are connected. This causes the nrpe daemons to
# accumulate, eating system resources. Do not set this too low.

connection_timeout=300



# WEEK RANDOM SEED OPTION
# This directive allows you to use SSL even if your system does not have
# a /dev/random or /dev/urandom (on purpose or because the necessary patches
# were not applied). The random number generator will be seeded from a file
# which is either a file pointed to by the environment valiable $RANDFILE
# or $HOME/.rnd. If neither exists, the pseudo random number generator will
# be initialized and a warning will be issued.
# Values: 0=only seed from /dev/[u]random, 1=also seed from weak randomness

#allow_weak_random_seed=1



# INCLUDE CONFIG FILE
# This directive allows you to include definitions from an external config file.

#include=<somefile.cfg>



# INCLUDE CONFIG DIRECTORY
# This directive allows you to include definitions from config files (with a
# .cfg extension) in one or more directories (with recursion).

#include_dir=<somedirectory>
#include_dir=<someotherdirectory>



# COMMAND DEFINITIONS
# Command definitions that this daemon will run.  Definitions
# are in the following format:
#
# command[<command_name>]=<command_line>
#
# When the daemon receives a request to return the results of <command_name>
# it will execute the command specified by the <command_line> argument.
#
# Unlike Nagios, the command line cannot contain macros - it must be
# typed exactly as it should be executed.
#
# Note: Any plugins that are used in the command lines must reside
# on the machine that this daemon is running on!  The examples below
# assume that you have plugins installed in a /usr/local/nagios/libexec
# directory.  Also note that you will have to modify the definitions below
# to match the argument format the plugins expect.  Remember, these are
# examples only!
# The following examples use hardcoded command arguments...

# command[check_users]=/usr/local/nagios/libexec/check_users -w 5 -c 10
# command[check_load]=/usr/local/nagios/libexec/check_load -w 15,10,5 -c 30,25,20
# command[check_hda1]=/usr/local/nagios/libexec/check_disk -w 20% -c 10% -p /dev/hda1
# command[check_zombie_procs]=/usr/local/nagios/libexec/check_procs -w 5 -c 10 -s Z
# command[check_total_procs]=/usr/local/nagios/libexec/check_procs -w 150 -c 200


# The following examples allow user-supplied arguments and can
# only be used if the NRPE daemon was compiled with support for
# command arguments *AND* the dont_blame_nrpe directive in this
# config file is set to '1'.  This poses a potential security risk, so
# make sure you read the SECURITY file before doing this.

command[check_users]=/usr/local/nagios/libexec/check_users -w $ARG1$ -c $ARG2$
#command[check_load]=/usr/local/nagios/libexec/check_load -w $ARG1$ -c $ARG2$
#command[check_disk]=/usr/local/nagios/libexec/check_disk -w $ARG1$ -c $ARG2$ -p $ARG3$
#command[check_procs]=/usr/local/nagios/libexec/check_procs -w $ARG1$ -c $ARG2$ -s $ARG3$

# This is added by me

command[check_users]=/usr/local/nagios/libexec/check_users -w 5 -c 10
command[check_load]=/usr/local/nagios/libexec/check_load -w 15,10,5 -c 30,25,20
command[check_hda1]=/usr/local/nagios/libexec/check_disk -w 80 -c 90
command[check_zombie_procs]=/usr/local/nagios/libexec/check_procs -w $ARG1$ -c $ARG2$ -s $ARG3$
command[check_procs]=/usr/local/nagios/libexec/check_procs -w $ARG1$ -c $ARG2$
command[check_cpu_custom]=/usr/local/nagios/libexec/cpu_ent $ARG1$
command[check_swap]=/usr/local/nagios/libexec/check_swap $ARG1$
command[check_disk]=/usr/local/nagios/libexec/check_disk $ARG1$
command[check_init_service]=/usr/local/nagios/libexec/check_init_service $ARG1$
command[check_cpu_stats]=/usr/local/nagios/libexec/check_cpu_stats $ARG1$
command[check_mem]=/usr/local/nagios/libexec/check_mem -w 20 -c 10
command[check_open_files]=/usr/local/nagios/libexec/check_open_files $ARG1$
command[check_yum]=/usr/local/nagios/libexec/check_yum
command[check_services]=/usr/local/nagios/libexec/check_services -p $ARG1$
command[check_test1]=/usr/local/nagios/libexec/check_test1 $ARG1$
command[check_services]=/usr/local/nagios/libexec/check_services -p $ARG1$
command[check_disk]=/usr/local/nagios/libexec/check_disk $ARG1$
log after telnet command

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tail /var/log/messages

-sh-3.2$ tail messages
Aug 28 23:41:16 RemoteServer yum-updatesd: error getting update info: failure: repodata/47505b86e100fa614360a4e93baaaff088af631ab99ff95387978bafa505971f-primary.sqlite.bz2 from Fossil_RPMS: [Errno 256] No more mirrors to try.
Aug 29 00:41:16 RemoteServer yum-updatesd: error getting update info: failure: repodata/47505b86e100fa614360a4e93baaaff088af631ab99ff95387978bafa505971f-primary.sqlite.bz2 from Fossil_RPMS: [Errno 256] No more mirrors to try.
Aug 29 01:41:16 RemoteServer yum-updatesd: error getting update info: failure: repodata/47505b86e100fa614360a4e93baaaff088af631ab99ff95387978bafa505971f-primary.sqlite.bz2 from Fossil_RPMS: [Errno 256] No more mirrors to try.
Aug 29 02:41:16 RemoteServer yum-updatesd: error getting update info: failure: repodata/47505b86e100fa614360a4e93baaaff088af631ab99ff95387978bafa505971f-primary.sqlite.bz2 from Fossil_RPMS: [Errno 256] No more mirrors to try.
Aug 29 03:41:16 RemoteServer yum-updatesd: error getting update info: failure: repodata/47505b86e100fa614360a4e93baaaff088af631ab99ff95387978bafa505971f-primary.sqlite.bz2 from Fossil_RPMS: [Errno 256] No more mirrors to try.
Aug 29 04:41:17 RemoteServer yum-updatesd: error getting update info: failure: repodata/47505b86e100fa614360a4e93baaaff088af631ab99ff95387978bafa505971f-primary.sqlite.bz2 from Fossil_RPMS: [Errno 256] No more mirrors to try.
Aug 29 05:41:16 RemoteServer yum-updatesd: error getting update info: failure: repodata/47505b86e100fa614360a4e93baaaff088af631ab99ff95387978bafa505971f-primary.sqlite.bz2 from Fossil_RPMS: [Errno 256] No more mirrors to try.
Aug 29 06:41:16 RemoteServer yum-updatesd: error getting update info: failure: repodata/47505b86e100fa614360a4e93baaaff088af631ab99ff95387978bafa505971f-primary.sqlite.bz2 from Fossil_RPMS: [Errno 256] No more mirrors to try.
Aug 29 07:04:03 RemoteServer nrpe[23270]: Host 10.10.10.10 is not allowed to talk to us!
Aug 29 07:04:03 RemoteServer nrpe[23270]: Host 10.10.10.10 is not allowed to talk to us!

Telnet command

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-sh-3.2$ netstat -lpn |grep 5666
# netstat -lpn |grep 5666
tcp        0      0 0.0.0.0:5666                0.0.0.0:*                   LISTEN      11581/nrpe 

Please help me.

Thanks in Advance.

Re: CHECK_NRPE: Error - Could not complete SSL handshake.

Posted: Tue Aug 29, 2017 8:38 am
by mcapra
Have you walked through some of the "Common Problems" documented in the knowledge base:
https://support.nagios.com/kb/category.php?id=93

Which operating system is NRPE installed on?

What documentation did you follow when installing NRPE on RemoteMachine?

Did you execute a service xinetd restart after adding your Nagios XI server's address to the only_from directive in /etc/xinetd.d/nrpe?

Can you share the output of the following commands executed from the CLI of RemoteMachine:

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service xinetd restart
ps aux | grep nrpe
ps aux | grep xinetd
cat /etc/*lease
iptables -S

Re: CHECK_NRPE: Error - Could not complete SSL handshake.

Posted: Tue Aug 29, 2017 12:16 pm
by dwhitfield
Thanks @mcapra!

I'd also be interested in the output of ./check_nrpe -H on both the remote server and XI.

Additionally, on the remote server, what's the output of /usr/local/nagios/bin/nrpe?

Re: CHECK_NRPE: Error - Could not complete SSL handshake.

Posted: Wed Aug 30, 2017 5:44 am
by raamardhani7
Hi mcapra,

yes i went through the document available in knowledge base.
Which operating system is NRPE installed on?

--> Red Hat Enterprise Linux Server release 5.11 (Tikanga)

What documentation did you follow when installing NRPE on RemoteMachine?


--> Please see attachment.
Installing_The_XI_Linux_Agent.pdf


service xinetd restart

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xinetd (pid  31515) is running...
ps aux | grep nrpe

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# ps aux | grep nrpe
nagios   11581  0.0  0.0   5116   904 ?        Ss   Aug28   0:00 nrpe -c /etc/nagios/nrpe.cfg -d
root     31526  0.0  0.0   4028   664 pts/0    R+   02:10   0:00 grep nrpe
ps aux | grep xinetd

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# ps aux | grep xinetd
root     31515  0.0  0.0   2848   892 ?        Ss   02:10   0:00 xinetd -stayalive -pidfile /var/run/xinetd.pid
root     31530  0.0  0.0   4028   668 pts/0    R+   02:10   0:00 grep xinetd
cat /etc/*lease

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# cat /etc/*lease
Red Hat Enterprise Linux Server release 5.11 (Tikanga)
iptables -S

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# iptables -S
iptables v1.3.5: Unknown arg `-S'
Try `iptables -h' or 'iptables --help' for more information.

# iptables -L
Chain INPUT (policy ACCEPT)
target     prot opt source               destination

Chain FORWARD (policy ACCEPT)
target     prot opt source               destination

Chain OUTPUT (policy ACCEPT)
target     prot opt source               destination
let me know if you want anything else.
Thanks.

Re: CHECK_NRPE: Error - Could not complete SSL handshake.

Posted: Wed Aug 30, 2017 9:01 am
by scottwilkerson
Ok, the following output is not consistent with following the Installing_The_XI_Linux_Agent.pdf document
raamardhani7 wrote:ps aux | grep nrpe

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    # ps aux | grep nrpe
    nagios   11581  0.0  0.0   5116   904 ?        Ss   Aug28   0:00 nrpe -c /etc/nagios/nrpe.cfg -d
    root     31526  0.0  0.0   4028   664 pts/0    R+   02:10   0:00 grep nrpe
This actually looks like you have possible also installed NRPE from an RPM
We really need to stop this process and remove the RPM

First lets try to find it

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rpm -q nrpe
if we do, remove it

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rpm -e nrpe
Then restart xinetd

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service xinetd restart
If you still get the same error, verify you have your XI servers IP in the following file /etc/xinetd.d/nrpe

Re: CHECK_NRPE: Error - Could not complete SSL handshake.

Posted: Thu Aug 31, 2017 7:58 am
by raamardhani7
Hello scottwilkerson,

You are genius. Its working for me. :) :)

Thank you so much.

you can close thread.

Re: CHECK_NRPE: Error - Could not complete SSL handshake.

Posted: Thu Aug 31, 2017 8:48 am
by scottwilkerson
Thanks! Glad we were able to assist in getting it working!