Wireshark mailing list archives
Re: How does tshark "synchronize" multiple interfaces?
From: Francesco Fondelli <francesco.fondelli () gmail com>
Date: Wed, 7 Feb 2018 09:50:59 +0100
Hi, try with/without the '-t' option (Use a separate thread per interface). If I recall correctly - in my case - the dumpcap behavior with -t looked similar to the one of your sniffer. If that is the point, you can play with PACKET_FANOUT/PACKET_FANOUT_HASH in your sniffer. http://man7.org/linux/man-pages/man7/packet.7.html https://stackoverflow.com/questions/41660747/linux-understanding-setsockopt- packet-fanout-for-network-scaling hope this helps ciao fra On Tue, Feb 6, 2018 at 8:54 PM, S. Jacobi <sjacobi () mailueberfall de> wrote:
On Tue, 6 Feb 2018 10:31:38 -0800 Guy Harris <guy () alum mit edu> wrote:On Feb 6, 2018, at 9:20 AM, Richard Sharpe <realrichardsharpe () gmail com> wrote:On Tue, Feb 6, 2018 at 9:07 AM, S. Jacobi <sjacobi () mailueberfall de> wrote:On Tue, 6 Feb 2018 09:05:14 -0800 Richard Sharpe <realrichardsharpe () gmail com> wrote:As far as I am aware it is the kernel that is doing this. Also, I believe that only Linux supports the any device.We are on Linux, yes, but we don't capture from any. tshark allows to specify multiple interfaces.I have not looked at the code, but I suspect that it is something like this: https://stackoverflow.com/questions/37294540/binding-the-af-packet-socket-to-all-interfacesThat is, the kernel is doing it.That's how the "any" device is implemented by libpcap, so that's what happens if you capture on the "any" device. However, if, in Wireshark or TShark or dumpcap, you capture from an explicitly specified list of interfaces containing more than one interface, there are multiple pcap_t's open, and packets are separately received from all of those pcap_t's and those are written to a single capture file. So if they aren't in timestamp order when you explicitly capture on more than one interface, that's dumpcap's fault (which means it's the fault of "Wireshark", in the sense of the entire Wireshark release, as dumpcap is the program that does the packet capturing for Wireshark and TShark), not the fault of the OS kernel.The packets out-of-timestamp-order are quite rare and always between two interfaces. It could be that dumpcap tries to put them in the correct order but fails to do so when one interface lags behind. Thanks for your answers anyway. ____________________________________________________________ _______________ Sent via: Wireshark-dev mailing list <wireshark-dev () wireshark org> Archives: https://www.wireshark.org/lists/wireshark-dev Unsubscribe: https://www.wireshark.org/mailman/options/wireshark-dev mailto:wireshark-dev-request () wireshark org?subject= unsubscribe
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Current thread:
- How does tshark "synchronize" multiple interfaces? S. Jacobi (Feb 06)
- Re: How does tshark "synchronize" multiple interfaces? Richard Sharpe (Feb 06)
- Re: How does tshark "synchronize" multiple interfaces? S. Jacobi (Feb 06)
- Re: How does tshark "synchronize" multiple interfaces? Richard Sharpe (Feb 06)
- Re: How does tshark "synchronize" multiple interfaces? Guy Harris (Feb 06)
- Re: How does tshark "synchronize" multiple interfaces? S. Jacobi (Feb 06)
- Re: How does tshark "synchronize" multiple interfaces? Francesco Fondelli (Feb 07)
- Re: How does tshark "synchronize" multiple interfaces? S. Jacobi (Feb 06)
- Re: How does tshark "synchronize" multiple interfaces? Richard Sharpe (Feb 06)
- Re: How does tshark "synchronize" multiple interfaces? Jeff Morriss (Feb 06)