[linux-dvb] Re: VPN with Netsystem, very slow

[Johannes Stezenbach <js@convergence.de>]

exploit crew wrote:
> bash-2.05b# ping www.somehost.com
> PING somehost.com (64.91.228.240): 56 octets data
> 64 octets from 64.91.228.240: icmp_seq=3 ttl=51 time=360.2 ms
> 64 octets from 64.91.228.240: icmp_seq=9 ttl=51 time=352.1 ms
> 64 octets from 64.91.228.240: icmp_seq=19 ttl=51 time=344.8 ms

Looks like a lot of lost packets. What happens if you play
with the packet size, e.g. 'ping --size 167 www.somehost.com'?

If you try test_sections from the dvb-apps package, do you see
the missing packets then?
http://www.linuxtv.org/mailinglists/linux-dvb/2003/10-2003/msg00421.html

MPE sections look like this:

                              Syntax            No. of bits
datagram_section() {
   table_id                                          8     
   section_syntax_indicator                          1     
   private_indicator                                 1     
   reserved                                          2     
   section_length                                   12     
   MAC_address_6                                     8     
   MAC_address_5                                     8     
   reserved                                          2     
   payload_scrambling_control                        2     
   address_scrambling_control                        2     
   LLC_SNAP_flag                                     1     
   current_next_indicator                            1     
   section_number                                    8     
   last_section_number                               8     
   MAC_address_4                                     8     
   MAC_address_3                                     8     
   MAC_address_2                                     8     
   MAC_address_1                                     8     
   if (LLC_SNAP_flag == "1") {
        LLC_SNAP()
   } else {
        for (j=0;j<N1;j++) {
            IP_datagram_data_byte                    8     
        }
   }
   if (section_number == last_section_number) {
        for (j=0;j<N2;j++) {
            stuffing_byte                            8     
        }
   }
   if (section_syntax_indicator =="0") {
        checksum                                    32     
   } else {
        CRC_32                                      32     
   }
}


Johannes


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