TCPDUMP help -- option question

[okorkie]

Hello,

I have a question regarding TCPDUMP. I'm looking to run a TCPDUMP command with either of the following options:

- I want to capture x number of packets (somewhere between 1 to 10 packets)

or

- I want to capture for x number of seconds (I will want to capture for 1 second or less). Is it possible to capture for a time period of less than whole numbers (i.e. 0.5 seconds or 0.3 seconds, etc)?

Thanks in advance!

[Rubberman]

You can specify the number of packets to capture with the -c count option, but as far as I know, there is no capture time argument. The only timing related option is -G rotate_seconds one which specifies the amount of time it will dump to a log file before rotating the logs and start a new one. That said, you can send a SIGINT signal to the tcpdump program which will signal it to stop, and that can be done with a script that would sleep some period of time and then signal tcpdump. The sleep command only supports seconds, but the usleep command supports microseconds.