[CentOS] tcpdump loses lots of packets

Sun Aug 14 22:04:25 UTC 2016
Anand Buddhdev <anandb at ripe.net>

On 14/08/16 12:20, Anand Buddhdev wrote:

Hi folks,

I've discovered something. See below:

> The packet rate is also not that high. From the sending side, this is
> what I have:
> # tcpreplay -i qtx:p1p1 5min.pcap

If I send packets without qtx, like this:

tcpreplay -i p1p1 5min.pcap

then tcpdump on the receiving box has no problem, and keeps up happily
with the queries, and receives all of them into the pcap file. It seems
like the qtx module is somehow interfering with the packet capture, but
I don't know how or why yet.

Anyway, for low packet rates, such as 20,000 q/s, qtx isn't necessary,
so I will not use it when I want to do packet captures.