On Dec 11, 2011, at 4:10 PM, abhinav narain wrote:
>> It sniffs for beacons by using bpf filter and keeps a per AP record of
>>> packet count etc in a table.
>>
>> So if that's all you're doing, you presumably don't have your own buffer
>> for packets; when you say "I already have 15% RAM being
When you talk about 15% RAM, do you actually mean working set or virtual
address space? Which version of linux are you using?
Regarding 802.11a/b/g/n, you cannot rely much on the radiotap header of a
beacon frame. The radiotap header will only tell you which band was the packet
transmitted on (
> It sniffs for beacons by using bpf filter and keeps a per AP record of
> > packet count etc in a table.
>
> So if that's all you're doing, you presumably don't have your own buffer
> for packets; when you say "I already have 15% RAM being eaten by the
> program, so I can't actually increase the b
On Dec 11, 2011, at 2:42 PM, abhinav narain wrote:
> It sniffs for beacons by using bpf filter and keeps a per AP record of
> packet count etc in a table.
So if that's all you're doing, you presumably don't have your own buffer for
packets; when you say "I already have 15% RAM being eaten by th
It sniffs for beacons by using bpf filter and keeps a per AP record of
packet count etc in a table.
Is poll() better than select ?
I can only see A,B,G in beacons in tcpdump code, reading the radiotap
header..
How can I infer an AP is N ?
On Sun, Dec 11, 2011 at 2:35 PM, Guy Harris wrote:
>
>
On Oct 14, 2011, at 2:51 PM, Magnus Gille wrote:
> I came across an issue with tcpdump where the linux kernel couldn't allocate
> memory properly when we ran tcpdump -s 0 on one of our boxes. Tcpdump sets
> snaplen to 65535 if -s 0 is provided and this became a problem for us, to
> get around thi
On Dec 11, 2011, at 11:17 AM, abhinav narain wrote:
>> What is "it"? Your program? Or just *some* program?
>>
> Its the return statement of perror.
Presumably you were calling perror() because some call returned -1; what call
was that? If something keeps returning -1 because, for example, i
RETURN VALUES
> Select() returns the number of ready descriptors that are contained in
> the descriptor sets, or -1 if an error occurred. If the time limit
> expires, select() returns 0. If select() returns with an error,
> includ-
> ing one due to an interrupted call, the descrip
On Dec 11, 2011, at 8:36 AM, abhinav narain wrote:
> the return value of error is -1,
> EINTR is 4.
For many UN*X APIs, "the return value" and "the error" are not the same; "the
return value" on an error is -1, and "the error" is in the variable "errno".
The select() man page on my system (not
I just ignored that case of return value -1 : and continued.
It works now.
The memory usage for two captures is 15%.
I think I din't gain much using select() !
Abhinav
On Sun, Dec 11, 2011 at 12:09 PM, wrote:
> -[ Sun, Dec 11, 2011 at 11:36:14AM -0500, abhinav narain ]
> > the return value
-[ Sun, Dec 11, 2011 at 11:36:14AM -0500, abhinav narain ]
> the return value of error is -1,
> EINTR is 4.
errno is EINTR.
If select returns -1, check for errno. If errno == EINTR, just retry.
-
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the return value of error is -1,
EINTR is 4.
Also, it keeps printing ": Resource temporarily unavailable"
though I don't have any error statement to be printed.
This is increasing CPU usage
Abhinav
On Sun, Dec 11, 2011 at 7:48 AM, wrote:
> I did not remember what select() uses to return the re
I did not remember what select() uses to return the readable file
descriptors, but I do remember that any select can be interrupted
while still waiting, and that the error is then EINTR, so you have
to catch this particular error and ignore it (ie. merely loop on
it).
Googling for "non-restartable
I used the FD_IFSET() way to fnd out the descriptor.
I have an issue,
For few time dispatch works fine, but after I write the stats to a file,
and the loop returns to phy0, the programs quits with switch condition of
-1.
I don't see why ? I have the pcap{0,1} to non blocking. But this does not
wo
On Dec 10, 2011, at 11:58 PM, Cedric Cellier wrote:
>> I got it to work.
> (...)
>>> default: /* We got traffic */
>>> pcap_dispatch(pcap0,-1, (void *) packet_callback, NULL);
>>> pcap_dispatch(pcap1,-1, (void *) packet_callback2, NULL);
>
> So that other may benefit from it in the fut
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