lists  /  announce  owl-users  owl-dev  john-users  john-dev  passwdqc-users  yescrypt  popa3d-users  /  oss-security  kernel-hardening  musl  sabotage  tlsify  passwords  /  crypt-dev  xvendor  /  Bugtraq  Full-Disclosure  linux-kernel  linux-netdev  linux-ext4  linux-hardening  PHC 
Open Source and information security mailing list archives
Hash Suite: Windows password security audit tool. GUI, reports in PDF.
[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]
Date:	Fri, 13 Apr 2007 18:41:11 +0200
From:	Eric Dumazet <>
To:	Daniel Schaffrath <>
Cc:	Ben Greear <>,
	Andi Kleen <>,,
Subject: Re: TCP connection stops after high load.

On Fri, 13 Apr 2007 18:10:12 +0200
Daniel Schaffrath <> wrote:
> On 2007/04/12  , at 20:19, Eric Dumazet wrote:
> >
> > Warning : tcpdump can lie, telling you packets being transmited  
> > several time.
> Maybe you have further pointers how come that tcpdump lies about  
> duplicated packets?

dev_queue_xmit_nit() is called before attempting to send packet to device.

If device could not accept the packet (hard_start_xmit() returns an error), packet is requeued and retried later.
each retry means call ev_queue_xmit_nit() again, so tcpdump/sniffers can 'see' packet transmited several times. 

This is why I asked for "tc -s -d qdisc" results : to check the requeue counter (not its absolute value, but relative to number of packets sent)

See dev_hard_start_xmit() in net/core/dev.c

To unsubscribe from this list: send the line "unsubscribe netdev" in
the body of a message to
More majordomo info at

Powered by blists - more mailing lists