[Nagiosplug-devel] [ nagiosplug-Bugs-1478287 ] check_dns fails with CNAMEs

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Bugs item #1478287, was opened at 2006-04-28 09:43
Message generated for change (Comment added) made by jfidell
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Category: None
Group: None
>Status: Open
Resolution: None
Priority: 5
Private: No
Submitted By: James (jfidell)
Assigned to: Nobody/Anonymous (nobody)
Summary: check_dns fails with CNAMEs

Initial Comment:
check_dns gives an error if the hostname being checked
is a CNAME instead of an A record:

DNS CRITICAL - '/usr/bin/nslookup -sil' msg parsing
exited with no address


This patch may be sub-optimal, but corrects the problem
for me:

--- check_dns.c~        Fri Apr 28 10:35:45 2006
+++ check_dns.c Fri Apr 28 10:35:52 2006
@@ -136,6 +136,13 @@
       non_authoritative = TRUE;
     }
 
+    else if ( strstr ( chld_out.line[i], query_address
) && !address ) {
+      if (( temp_buffer = strstr ( chld_out.line[i] +
strlen ( query_address ),
+          _("canonical name = ")))) {
+        address = strdup ( temp_buffer );
+      }
+    }
+
     result = error_scan (chld_out.line[i]);
     if (result != STATE_OK) {
       msg = strchr (chld_out.line[i], ':');


James

----------------------------------------------------------------------

>Comment By: James (jfidell)
Date: 2007-06-11 09:05

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OS is FreeBSD 6.0.  Not sure about the nslookup version as it seems to
defy my attempts to find out.

IIRC correctly (as this was some time ago), the problem is not
specifically that the format of output of
nslookup is different, but that in same circumstances check_dns
mis-handles the output.  I *think*
the problem is that for some configurations (could be where the CNAME is
in a different domain, or where
it is served by a different nameserver, or perhaps just depending on the
nameserver implementation),
nslookup may not return a "Name:" or "Address:" line at all, even though
the nameserver being queried can
and does answer properly that the queried hostname is a canonical name.

----------------------------------------------------------------------

Comment By: Matthias Eble (psychotrahe)
Date: 2007-06-11 08:17

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Announced pending state by sending emails to the participants.

----------------------------------------------------------------------

Comment By: Matthias Eble (psychotrahe)
Date: 2007-06-04 16:00

Message:
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Which OS version/nslookup version are you running? On Ubuntu Linux (6.06)
everything is fine with cnames, too.

nslookup output looks like this:

...
foo.de.tld canonical name = bar.tld.
Name:   bar.tld
Address: x.x.x.x

Could you post your output, too?

Thanks Matthias

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