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    <p>First of all, there's an already written <a href="http://pypi.python.org/pypi/snmp-passpersist" rel="nofollow">snmp-passpersist Python module</a> specifically for this task. Its page has a link to a real-world usage example. An example code for your case is below.</p> <p>Regarding your specific questions: </p> <ol> <li><p>The description of <code>getnext</code> is indeed notoriously unclear in both specification and wikipedia. It is explained well in <a href="http://www.net-snmp.org/wiki/index.php/TUT%3asnmpgetnext" rel="nofollow">TUT:snmpgetnext - Net-SNMP Wiki</a>.<br/><br/> In brief, it retrieves <em>the first valid OID</em> (and its value) <em>that goes after the specified one in the agent's hierarchy</em>. The "hierarchy" here can be represented as an ordered list of all OIDs the agent knows of that are valid at the moment.</p> <ul> <li>There are two major use cases for this: <ol> <li>The response <em>contains the OID</em> of that "next" value as well as the value itself. So you can <em>walk the hierarchy</em> at the agent by using returned OIDs in subsequent requests. The agent is supposed to return the "not found" error (and <code>pass_persist</code> handler - <code>"NONE"</code>) when the hierarchy is exhausted.</li> <li>You can <em>specify an incomplete OID</em> too, and the agent is supposed to return <em>the first complete one it knows of</em> that matches the one provided.</li> </ol></li> <li>At packet level, <code>getnext</code> is indeed different from <code>get</code> too (its request type ID is <code>1</code>, <code>get</code>'s is <code>0</code>).</li> <li>You might want to ignore this "magic" altogether and handle it the same way as <code>get</code>: this only means that "walking" and "guessing" will not work (walking might loop indefinitely). This is how a handler I maintained at my last occupation worked <strong>and this is just what is happening in your present code too :^)</strong>.</li> <li><ul> <li>So, the fix is simple: <code>getFileLine(int(sub_oid)+1, lines)</code> - since your code is already smart enough to return <code>"NONE"</code> on exhaustion. "Guessing" will still not work, but... do you need it?</li> </ul></li> </ul></li> <li><p><code>net-snmpd</code> has a plethora of logging options - search "log" on <a href="http://www.net-snmp.org/docs/man/snmpd.html" rel="nofollow">its manpage</a> (and, hell, it's free software! you can always consult or even debug the source when all else fails). But in this particular case, logging stdin and stdout while giving queries with <code>snmpget</code>/<code>snmpgetnext</code> and/or using sniffer is more than enough.</p></li> </ol> <p>With the aforementioned <code>snmp-passpersist</code>, your code boils down to:</p> <pre><code>base_oid=".1.3.6.1.4.1..[snip]" data_file="&lt;path&gt;" import snmp_passpersist as snmp pp=snmp.PassPersist(base_oid) for l in (l.rstrip() for l in open(data_file)): pp.add_int(l,int(l)) pp.start(user_func=lambda:True,refresh=1800) # If data updates are needed, # replace lambda with a real fn # and adjust refresh (sec) </code></pre> <p>If you need to monitor changes to the file, you can either poll it (like the comment above suggests to) or (in Linux) use something like <a href="https://github.com/seb-m/pyinotify/wiki" rel="nofollow">pyinotify</a> - in this case, you'll probably need to replace <code>pp.main_update()</code> before calling <code>pp.start()</code> or otherwise patch up the module's machinery somehow.</p>
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    1. COI know of the pre-exsiting module, but i was hoping to avoid any external dependencies. Thanks for the pointers though, it helps alot. Given the issues with the inotify being needed, I might just have to suck it up though. As you say, it would be better (easier!) to use existing code.
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    2. COWell, if you read carefully, I provided a fix for your existing code too.
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    3. COThe snmp-passpersist code you mention seems to work if I walk the exact oid, but if i walk anything higher i just get No such instance currently exists at this OID. Is that module meant to support getnext / walking, or is that similar to my original code ?
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