使用PHP解析SNMP响应

Question

I'm currently successfully reading out several properties on our switches over SNMP with php. Now i'm looking at making the resulting output of snmpget and snmpwalk actually usefull for the consumers of our API's.

Problem is that the responses look like this: INTEGER: up(1) and INTEGER: 10103 ...

Is there any convention/standard on how to parse this response format or is the response vendor specific for each device we are trying to read?

Is there by any chance already a PHP library, function or extension that can cast these responses in php native variables or at least something usefull that we can work with?

---

UPDATE:

I've found out a few new things namely that there are indeed several libraries in php that can parse binary ASN.1 strings which basically are BER encoded strings if i'm right. Problem is that i can't seem to find a way to get the binary data from the devices with php ...

Answer 1

I'm not sure about your particular PHP methods, but the difference between your two INTEGER examples is likely to be whether your system has an SNMP MIB corresponding to the OID (e.g. to determine that 1 means "up").

If you only want the integers, you should be able to pass a parameter to your get or walk command. For example, net-snmp's snmpget or snmpwalk commands will take -Oe to remove symbolic labels. From the manpage:

              $ snmpget -c public -v 1 localhost ipForwarding.0
              IP-MIB::ipForwarding.0 = INTEGER: forwarding(1)
              $ snmpget -c public -v 1 -Oe localhost ipForwarding.0
              IP-MIB::ipForwarding.0 = INTEGER: 1

If you are parsing net-snmp output, I recommend reading the snmpcmd man page as it has a lot of output options that will interest you especially the display of other types such as timeticks and strings.

If you do want to retrieve SNMP in PHP you could look at how Cacti does it.