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dumpcap - get packet drop report periodically

asked 2020-05-23 15:12:40 +0000

balderman gravatar image

updated 2020-05-23 15:13:10 +0000

when dumpcap is stopped it prints a short packets stats report. Example

Packets received/dropped on interface 'eno2': 138657725/12413592 (pcap:12413591/dumpcap:1/flushed:0/ps_ifdrop:109) (91.8%)

Source code:

It it possible to get this report periodically? (without stopping dumpcap)


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answered 2020-05-23 22:54:07 +0000

Guy Harris gravatar image

There's no mechanism to get dumpcap to periodically produce the report.

On BSD-derived OSes, such as macOS and the *BSDs, you can send it the SIGINFO signal to get the report printed.

If you're running it from a terminal, and the stty -a command prints

cchars: ...
    ... status = ^T;

(the only thing that's relevant is status = ^T;; I've omitted the rest of the stuff it prints), you can type ^T while dumpcap is running in the foreground and it should print that information. If something such as status = <undef> is printed, do stty status '^t' first.

If you're not running it from a terminal or it's in the background, the kill command can be used to send the signal.

If you're on any other OS, you're out of luck.

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answered 2020-05-23 20:01:06 +0000

Jaap gravatar image

You can send it SIGINFO to provoke it printing the stats. Conditions apply, see source code.

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The main condition that applies is "this has to be a BSD-derived OS, such as macOS or one of the *BSDs".

Guy Harris gravatar imageGuy Harris ( 2020-05-23 22:47:59 +0000 )edit

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Asked: 2020-05-23 15:12:40 +0000

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Last updated: May 23 '20