On Mon, 8 Apr 2002, Zhu Ying Jie wrote:
> Hi,
> I am currently working on a network simulator (working under
> Linux 2.4.2) in which tcpdump can work. But the tcpdump uses the real
> system time instead of the virtual time of the simulated network. Can
> anyone tell me how to associate the tcpdump with the virtual clock of the
> simulated system?
>
I have developed a similar simulator, thats why i am trying to reply.
But i am not an expert here at all.
The time-stamp is assigned by the libpcap library.
Are you taking traffic online or offline? Because if it is offline,
already timestamp is written to dump-file. In that case after every packet
is read from that file, you can change the time with your simulator time.
The actual code is in pcap_offline_read() function of savefile.c file
which will be in libpcap directory.
In case of online traffic you have to bypass an ioctl in pcap_read()
function of pcap-linux.c file in libpcap directory.
The actual ioctl is: (ioctl(p->fd, SIOCGSTAMP, &h.ts)
Instead of this, you assign your simulated time into "h.ts".
Cheers,
Saif
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