Pass persist - Revision history

Rstory: move content to Tut:Extending_snmpd_using_shell_scripts

2012-03-30T09:57:49Z

move content to Tut:Extending_snmpd_using_shell_scripts

Abayley at 19:44, 26 October 2011

2011-10-26T19:44:53Z

Abayley at 20:32, 5 September 2011

2011-09-05T20:32:26Z

Abayley at 09:29, 2 September 2011

2011-09-02T09:29:52Z

Abayley at 09:28, 2 September 2011

2011-09-02T09:28:47Z

Abayley at 09:27, 2 September 2011

2011-09-02T09:27:50Z

Abayley at 09:23, 2 September 2011

2011-09-02T09:23:23Z

Abayley at 09:22, 2 September 2011

2011-09-02T09:22:05Z

Abayley: Created page with "The pass_persist option is very useful if you need to implement some specific OID subtree, but it has a few traps and features which are poorly communicated, or not even mentione..."

2011-09-02T09:19:44Z

Created page with "The pass_persist option is very useful if you need to implement some specific OID subtree, but it has a few traps and features which are poorly communicated, or not even mentione..."

New page

The pass_persist option is very useful if you need to implement some specific OID subtree, but it has a few traps and features which are poorly communicated, or not even mentioned in the snmpd.conf man page.

# the shutdown protocol: when the snmpd server wants to shutdown, it tells your script by sending a blank line on stdin.
# snmpd sends a PING at the start of every request (I read the docs to mean that it is sent once, on script startup).
# the list of types you can return is quite limited. It is actually described in the docs for pass, which says that the type must be "one of the text strings: integer, gauge, counter, timeticks, ipaddress, objectid, or string"
# because you cannot return DateAndTime (RFC 2579), for datetime values I've resorted to returning two values (two separate OIDs):
## seconds-since-epoch
## datetime formatted as ISO-8601 string

Other things I've learned:

# your MIB must be valid, otherwise snmpget won't even query the daemon.
# you will probably need to add a line to the security section of snmpd.conf, to allow access to the OID subtree.

@@ Line 1: / Line 1: @@
-The pass_persist option is very useful if you need to implement some specific OID subtree, but it has a few traps and features which are poorly communicated, or not even mentioned in the snmpd.conf man page.
+#REDIRECT [[Tut:Extending_snmpd_using_shell_scripts]]
-−
-# the shutdown protocol: when the snmpd server wants to shutdown, it tells your script by sending a blank line on stdin.  (http://dreness.com/wikimedia/index.php?title=Net_SNMP)
-# snmpd sends a PING at the start of every request (I read the docs to mean that it is sent once, on script startup).
-# the list of types you can return is quite limited. It is actually described in the docs for pass, which says that the type must be "one of the text strings: integer, gauge, counter, timeticks, ipaddress, objectid, or string"
-# because you cannot return DateAndTime (RFC 2579), for datetime values I've resorted to returning two values (two separate OIDs):
-## seconds-since-epoch (type counter)
-## datetime formatted as ISO-8601 string (type string)
-# there doesn't seem to be a way for getnext to distinguish between an invalid input OID, and running past the end of the supported tree.
-−
-−
-Other things I've learned:
-−
-# your MIB must be valid, otherwise snmpget won't even query the daemon.
-# you will probably need to add a line to the security section of snmpd.conf, to allow access to the OID subtree e.g. something like (where nnnnn is your Private Enterprise Number): <pre>view all    included    .1.3.6.1.4.1.nnnnn</pre>
-# I used python to implement my pass_persist script. You must flush stdout after sending each line, otherwise snmpd will timeout after waiting for your response. Or invoke python with -u option (unbuffered stdin/stdout).
-# python stdin.readline() preserves the newline, so you need to strip it.
-−
-−
-My pass_persist daemon main loop looks like this:
-−
-<pre>
-    def getline():
-        return sys.stdin.readline().strip()
-−
-−
-    def output(line):
-        sys.stdout.write(line + "\n")
-        sys.stdout.flush()
-−
-−
-    def main():
-        logger.info("starting pass_persist daemon")
-−
-        try:
-            while True:
-                command = getline()
-−
-                if command == "":
-                    logger.info("stopping pass_persist daemon")
-                    sys.exit(0)
-−
-                # snmpd 5.4.2.1 sends a PING before every snmp command
-                elif command == "PING":
-                    output("PONG")
-−
-                elif command == "set":
-                    oid = getline()
-                    type_and_value = getline()
-                    logger.info("%s %s %s" % (command, oid, type_and_value))
-                    #snmp_set(oid, type_and_value)
-                    # set not supported yet...
-                    output("not-writable")
-−
-                elif command == "get":
-                    oid = getline()
-                    logger.info("%s %s" % (command, oid))
-                    snmp_get(oid)
-−
-                elif command == "getnext":
-                    oid = getline()
-                    logger.info("%s %s" % (command, oid))
-                    snmp_getnext(oid)
-−
-                else:
-                    logger.error("Unknown command: %s" % command)
-−
-        # If we get an exception, spit it out to the log then quit
-        # (by propagating exception).
-        # snmpd will restart the script on the next request.
-        except Exception, e:
-            logger.exception("")
-            raise
-−
-</pre>

@@ Line 70: / Line 70: @@
          # snmpd will restart the script on the next request.
          except Exception, e:
-             logger.error(traceback.format_exc(10000))
+             logger.exception("")
              raise
 </pre>

@@ Line 5: / Line 5: @@
 # the list of types you can return is quite limited. It is actually described in the docs for pass, which says that the type must be "one of the text strings: integer, gauge, counter, timeticks, ipaddress, objectid, or string"
 # because you cannot return DateAndTime (RFC 2579), for datetime values I've resorted to returning two values (two separate OIDs):
-## seconds-since-epoch
+## seconds-since-epoch (type counter)
-## datetime formatted as ISO-8601 string
+## datetime formatted as ISO-8601 string (type string)
@@ Line 12: / Line 13: @@
 # your MIB must be valid, otherwise snmpget won't even query the daemon.
-# you will probably need to add a line to the security section of snmpd.conf, to allow access to the OID subtree.
+# you will probably need to add a line to the security section of snmpd.conf, to allow access to the OID subtree e.g. something like (where nnnnn is your Private Enterprise Number): <pre>view all    included    .1.3.6.1.4.1.nnnnn</pre>
 # I used python to implement my pass_persist script. You must flush stdout after sending each line, otherwise snmpd will timeout after waiting for your response. Or invoke python with -u option (unbuffered stdin/stdout).
 # python stdin.readline() preserves the newline, so you need to strip it.

@@ Line 14: / Line 14: @@
 # you will probably need to add a line to the security section of snmpd.conf, to allow access to the OID subtree.
 # I used python to implement my pass_persist script. You must flush stdout after sending each line, otherwise snmpd will timeout after waiting for your response. Or invoke python with -u option (unbuffered stdin/stdout).
-# python stdin.getline() preserves the newline, so you need to strip it.
+# python stdin.readline() preserves the newline, so you need to strip it.

← Older revision		Revision as of 09:27, 2 September 2011
Line 14:		Line 14:
	# you will probably need to add a line to the security section of snmpd.conf, to allow access to the OID subtree.		# you will probably need to add a line to the security section of snmpd.conf, to allow access to the OID subtree.
	# I used python to implement my pass_persist script. You must flush stdout after sending each line, otherwise snmpd will timeout after waiting for your response. Or invoke python with -u option (unbuffered stdin/stdout).		# I used python to implement my pass_persist script. You must flush stdout after sending each line, otherwise snmpd will timeout after waiting for your response. Or invoke python with -u option (unbuffered stdin/stdout).
		+	# python stdin.getline() preserves the newline, so you need to strip it.