The Timestamp is in the packet header - here is a code snippet that I use as a callback to Net::Pcap::loop - this should help to get you started, including obtaining the timestamp: 
sub process_pkt {
    my($user, $hdr, $pkt) = @_;
    my $currentmac = 0; # Client mac unidentified.(init)
      warn ("Bad user data\n"), if ($user ne "abc");
      warn("Bad pkthdr\n"), if (!defined($hdr));
      warn("Bad pkt data\n"), if (!defined($pkt));

    my ($sec,$min,$hour) =localtime($hdr->{tv_sec});
    my $len= $hdr->{len};
    my $buf;
    my $eth_obj = NetPacket::Ethernet->decode($pkt);
    #print("$eth_obj->{src_mac}:$eth_obj->{dest_mac} " .
    #      "$Ethernet_Type_Name{$eth_obj->{type}} \n");
    $buf = sprintf("%02d:%02d:%02d.%03d[%4d] ",
           $hour,$min,$sec, $hdr->{tv_usec} / 1000,$hdr->{len});
    return unless $eth_obj->{type} == ETH_TYPE_IP; # Only Handle IP4
    Decode_IP( $eth_obj,\$buf, $hdr);

   $count++;
}

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     "For every complex problem, there is a simple answer ... and it is wrong." --H.L. Mencken

In reply to Re: timestamp of the IP-Header -netpacket::ip by NetWallah
in thread timestamp of the IP-Header -netpacket::ip by Mad-MaX

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