How to use a pcap file

MetaGeek Products inSSIDer
#1

Can inSSIDer playback a saved pcap file?
Can the user adjust the playback speed, skip forward or go back?
Can the user drill down during playback?

During playback I’ve seen a short segment of a recording over several hours, which during a 10 minute window shows there had been a signal. The progress bar goes from left to right once.

I seem to have a Wi-Fi signal from an unknown source in my house that appears only for brief intervals and wondered if saving a pcap file over a period of several hours might allow me to examine this signal via playback in inSSIDer and determine any information about any clients. I’ve not been able to catch it in realtime using inSSIDer, because the signal is gone before I can examine it.

Any recommendationof a tool to read a pcap file? (preferable free)
I downloaded Pcap Analyzer and JRE, but the Pcap Analyzer jar file is not executing - temporarily opens a window but exits immediately.

#2

ps
Microsoft Network Monitor 3.4 found in my saved pcap file:
Frame: Number = 1335679, Captured Frame Length = 275, MediaType = Unhandled Media Type 57471
The only differences I saw in the frame list were truncated frames.
I can’t make any sense out of the frame hex data.

I guess that means data is being sent, but I have no clue as to what the data is or anything else about the traffic on this wireless network.

#3

Wireshark did a better job with my saved pcap files.
While I thought I was capturing only traffic from 1 SSID, not so. In fact, Wireshark did not find that SSID in the file.
None of my pcap files collected to date contain that SSID.

#4

Got a pcap file that has a few packets from my sought source, displayed by Wireshark.
They are probe requests.