sniffer in python

Peter Hansen peter at
Tue Aug 16 03:24:26 CEST 2005

billiejoex wrote:
> Thank you for your fast reply. You're right. I'll be more specific, sorry.
> The example source is the one you can find on the 'Impacket' page on the 
> same site of pcapy:
> I use a Win XP prof sp2 system, python ver. 2.4.1.
> Here's the output:
> C:\Python24>
> Traceback (most recent call last):
> File "C:\Python24\", line 107, in ?
> main(filter)
> File "C:\Python24\", line 88, in main
> dev = getInterface()
> File "C:\Python24\", line 81, in getInterface
> print '%i - %s' % (count, iface)
> File "C:\Python23\lib\encodings\", line 18, in encode
> return codecs.charmap_encode(input,errors,encoding_map)
> UnicodeEncodeError: 'charmap' codec can't encode characters in position 
> 4-19: ch
> aracter maps to <undefined>

Helping you learn to troubleshoot from tracebacks: look at the line 
preceding the failing call.  Can you guess anything about what in that 
line might be causing an encode() call?  The count variable is, 
presumably, just an integer, so %i wouldn't like have to do more than 
convert it to a string.  %s, however, asks for "iface" to be turned into 
a string... if it were not already a string (i.e. it's a unicode?) it 
would have to be encoded.  What does iface contain and where did it come 
from?  Can you make it be just a string?  Does that change or fix anything?


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