check_tcp function issue

[perezlou]

I'm having a problem with Nagios XI whereby TCP client socket connections remain open indefinitely. In order to troubleshoot, I am running the VMware CENTOS package inside a VMPlayer environment.

Nagios seems to constantly try to open and close a connection apparently expecting the target socket to respond. If it does not, Nagios will continue to retry opening and closing on that same port. The existing connection attempts will remain “active” and do not close out. Because Nagios will continue to make attempts to connect, the Windows TCP/IP driver will start to “stack up” these “CLOSE_WAIT” connections over time.

The problem with this scenario, with enough multiple “CLOSE_WAIT” connections pending, is existing connections become destabalized. Existing traffic may halt and TCP network error conditions start occuring.

So the question I am trying to answer is:
"Is there a setting I can apply to Nagios in order to “timeout” and close sockets so that there isn’t an accumulation of leftover connection attempts which causes instability in the Windows TCP/IP driver."

[scottwilkerson]

In order to troubleshoot what you describe, could you send your configuration for the checks that are causing this behavior as I have never heard of this before?

check_tcp does have a -t flag where you can specify a timeout...

Code: Select all

[root@localhost libexec]# ./check_tcp -h
check_tcp v1991 (nagios-plugins 1.4.13)
Copyright (c) 1999 Ethan Galstad <[email protected]>
Copyright (c) 1999-2008 Nagios Plugin Development Team
        <[email protected]>

This plugin tests TCP connections with the specified host (or unix socke

Usage:check_tcp -H host -p port [-w <warning time>] [-c <critical time>]
[-e <expect string>] [-q <quit string>][-m <maximum bytes>] [-d <delay>]
[-t <timeout seconds>] [-r <refuse state>] [-M <mismatch state>] [-v] [-
[-D <days to cert expiry>] [-S <use SSL>] [-E]

Options:
 -h, --help
    Print detailed help screen
 -V, --version
    Print version information
 -H, --hostname=ADDRESS
    Host name, IP Address, or unix socket (must be an absolute path)
 -p, --port=INTEGER
    Port number (default: none)
 -4, --use-ipv4
    Use IPv4 connection
 -6, --use-ipv6
    Use IPv6 connection
 -E, --escape
    Can use \n, \r, \t or \ in send or quit string. Must come before sen
    Default: nothing added to send, \r\n added to end of quit
 -s, --send=STRING
    String to send to the server
 -e, --expect=STRING
    String to expect in server response (may be repeated)
 -A, --all
    All expect strings need to occur in server response. Default is any
 -q, --quit=STRING
    String to send server to initiate a clean close of the connection
 -r, --refuse=ok|warn|crit
    Accept tcp refusals with states ok, warn, crit (default: crit)
 -M, --mismatch=ok|warn|crit
    Accept expected string mismatches with states ok, warn, crit (defaul
 -j, --jail
    Hide output from TCP socket
 -m, --maxbytes=INTEGER
    Close connection once more than this number of bytes are received
 -d, --delay=INTEGER
    Seconds to wait between sending string and polling for response
 -D, --certificate=INTEGER
    Minimum number of days a certificate has to be valid.
 -S, --ssl
    Use SSL for the connection.
 -w, --warning=DOUBLE
    Response time to result in warning status (seconds)
 -c, --critical=DOUBLE
    Response time to result in critical status (seconds)
 -t, --timeout=INTEGER
    Seconds before connection times out (default: 10)
 -v, --verbose
    Show details for command-line debugging (Nagios may truncate output)