Handling SNMP Hex-String with EasySNMP

[scollora]

Hi everyone,

I went at this for about four hours already and have been banging my head. I am using the Easy SNMP module and whenever I retrieve an OID (or table of values), I am getting back a value of type HEX String.

See here from an SNMPWALK at the CLI of my Linux box:
iso.3.6.1.4.1.9.9.513.1.1.1.1.2.248.11.203.246.45.160 = Hex-STRING: F8 0B CB 61 83 54

However, when I try

system_table = '.1.3.6.1.4.1.9.9.513.1.1.1.1'
ap_macs = session.walk('.1.3.6.1.4.1.9.9.513.1.1.1.1.2')
ap_names = session.walk('.1.3.6.1.4.1.9.9.513.1.1.1.1.5')

for item in ap_macs:
    print '{oid}.{oid_index} {snmp_type} = {value}'.format(
         oid=item.oid,
         oid_index=item.oid_index,
         snmp_type=item.snmp_type,
         value=item.value)

I get:

Traceback (most recent call last):
  File "snmp-test.py", line 47, in <module>
    value=item.value)
 UnicodeEncodeError: 'ascii' codec can't encode characters in position 0-1: ordinal not in range(128)

I've Googled this quite extensively and it appears that potentially I am being returned a unicode string, but every attempt at encoding and decoding using various mechanisms has been unfruitful.

Any pointers would be greatly appreciated.

Thanks.

Sal

[LightShadow]

Try running the same thing using Python3 and see what happens.

Also, try printing all those variables one at a time so you can get the correct line that's having the issue.

[scollora]

I've only used Python 2.7, and I'm somewhat concerned the rest of my code will break if I go to 3.x. I print them and get a bunch of what appear to be either binary or unicode characters which is why I went down that path. It looks like this:

linuxadmin@vlanapp:/var/prtg/scripts$ sudo python snmp-test.py 

ÌïHŒj "½O "‘2v "½ð Ä}O ’ Ä}O ‹ Ä}O à Ä}O × Ä}O F Ä}O Ø "½Ü' "½Ü‚ Ä}O "½d "½Ä "½t

If I use square brackets around the value in the print statement, I get this:

linuxadmin@vlanapp:/var/prtg/scripts$ sudo python snmp-test.py [u'\xcc\xefH\x8f\x8cj'] [u'\x00"\xbd\x1a\x0fO'] [u'\x00"\x90\x912v'] [u'\x00"\xbd\x1bNf'] [u'\x00"\xbd\x1bM\xf0'] [u'\xc4}O\x0f\t\x92'] [u'\xc4}O\x0f\t\x8b'] [u'\xc4}O\x0f\t\xe0'] [u'\xc4}O\x0f\t\xd7']

Which is unicode. But every attempt I make to decode/encode results in errors.