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  Sat (Satellite Technology) HOWTO
  Roberto Arcomano berto@fatamorgana.com, Florindo Santoro
  flosan@hack-it.net
  v1.81 - July 31, 2002

  Sat technology is starting to become a great resource for Internet
  users, allowing high bandwidth in downloading and many other interest�
  ing services.  This document wants to investigate "State of Art" of
  Sat connections in Linux environment, how to get them speeder and to
  share with many clients. You can found latest version of this document
  at http://www.fatamorgana.com/bertolinux <http://www.fatamor�
  gana.com/bertolinux> and http://www.hack-it.net/How-To/Sat-HOWTO.html
  <http://www.hack-it.net/How-To/Sat-HOWTO.html>.
  ______________________________________________________________________

  Table of Contents



  1. Introduction

     1.1 Introduction
     1.2 Copyright
     1.3 Translations
     1.4 Credits

  2. Background Knowledge

     2.1 What about satellite
     2.2 How does it work?
     2.3 Other technologies
     2.4 What is the max bandwidth?
     2.5 How much does it cost?
        2.5.1 Hardware costs
        2.5.2 Account costs
     2.6 What are the satellites used?
     2.7 What ISPs give Sat Internet Access?
     2.8 What else?

  3. Technical Information

     3.1 General working
     3.2 Frequencies
     3.3 DVB Receiver Card
     3.4 Data Link Level DVB setting
     3.5 TCP/IP working
     3.6 Authentication
     3.7 Services I can use with a sat connection

  4. Requirements

     4.1 Knowledge requirement
     4.2 Hardware
     4.3 Software
     4.4 TV Software
        4.4.1 Under Windows
        4.4.2 Under Linux

  5. Base setup

     5.1 First: mounting
     5.2 Calibrating
     5.3 Double Feed
     5.4 Data-link level adjusting

  6. Configuration under Linux

     6.1 Drivers installation
     6.2 Setting up /etc/dvbd.conf
     6.3 Dvbd daemon
     6.4 How to config EON service
     6.5 How to use Netsystem service
        6.5.1 VPN connection
        6.5.2 Patch for pppd
        6.5.3 Routing settings
        6.5.4 Patch for dvbd.c
        6.5.5 Test it
        6.5.6 Get performance better
        6.5.7 Sharing Netsystem with many clients
     6.6 How to use Sat Node service
     6.7 OpenSky service under Linux

  7. Configuration under Windows

     7.1 EON
     7.2 Netsystem
     7.3 OpenSky

  8. Appendix A - Notes

     8.1 Translation Dynamic IP -> MAC Address
     8.2 TCP Window
     8.3 Download accelerator
        8.3.1 Under Linux
        8.3.2 Under Windows

  9. Appendix B - Well Known Sat ISP setting value

     9.1 EuropeOnLine
        9.1.1 Transponder 113
        9.1.2 Transponder 114
        9.1.3 Transponder 115
        9.1.4 Transponder 103
     9.2 Netsystem
        9.2.1 Transponder 119
     9.3 Sat Node
     9.4 Open Sky

  10. Links

     10.1 Open
     10.2 Commercial


  ______________________________________________________________________

  1.  Introduction

  1.1.  Introduction

  This document wants to explain something about Satellite technology,
  how it works, what do you need, configuration and how to sharing it
  between several clients. Satellite connections are very different from
  terrestrial ones, they require more attention to setup and also some
  more care to maintain them stable (snow or strong rain could prevent
  you to have a good signal).

  Feedback are welcome, don't hesitate to contact us:
  berto@fatamorgana.com <mailto:berto@fatamorgana.com> and flosan@hack-
  it.net <mailto:flosan@hack-it.net>.

  1.2.  Copyright

  Copyright (C) 2000,2001 Roberto Arcomano, Florindo Santoro. This
  document is free; you can redistribute it and/or modify it under the
  terms of the GNU General Public License as published by the Free
  Software Foundation; either version 2 of the License, or (at your
  option) any later version. This document is distributed in the hope
  that it will be useful, but

  WITHOUT ANY WARRANTY; without even the implied warranty of
  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
  General Public License for more details. You can get a copy of the GNU
  GPL here <http://www.gnu.org/copyleft/gpl.html>

  1.3.  Translations

  If you want to translate this document you are free, you only have to:



  1. Check that another version of it doesn't already exist at your
     local LDP

  2. Maintain all 'Introduction' section (including 'Introduction',
     'Copyright',

  Warning! You don't have to translate TXT or HTML file, you have to
  modify LYX file, so that it is possible to convert it all other
  formats (TXT, HTML, RIFF, etc.): to do that you can use "LyX"
  application you download from http://www.lyx.org <http://www.lyx.org>.

  No need to ask me to translate! You just have to let me know (if you
  want) about your translation.

  Thank you for your translation!

  1.4.  Credits

  Thanks to Fatamorgana Computers <http://www.fatamorgana.com> for
  hardware equipment and experimental opportunity.

  Thanks to Linux Documentation Project <http://www.linuxdoc.org> for
  publishing and uploading my document in a very quickly fashion.

  Thanks to Pierre Guiral and Andrei Boros for their help.

  2.  Background Knowledge

  2.1.  What about satellite

  In the last few years satellite began to be applied in Internet
  networking, mainly by medium-big ISPs and we have seen it diffused
  between users. Sat connections are a very different kind of networking
  than terrestrial ones, with different timing such as higher RTT (round
  trip time), but also with different bandwidth value, up to 2 Mbps or
  more.

  2.2.  How does it work?

  We can imagine a path like this:


                |||||| S A T E L L I T E  ||||||||
                     /                       /|\
  Downl             /                         |      Uploading
  load             /                          |      from
  to              /(4)                        | (3)  server
  client         /                            |
                /                             |
  SatCard(parabolic antenna)                  |
               |                              |
              \|/                             |
         USER PC ----make request-----> SAT-SERVER <---retrieving---> INTERNET
                           (1)                               (2)



  So first we make the request (1) (using our Internet connection) to
  the Sat-Server, after it will retrieve out info from Internet (2) and
  it will send it to Satellite (3); in the end we would receive data
  from the it (4) to our home using a parabolic antenna and a Sat Card.

  Typically exist 2 kinds of request :



  �  Http

  �  Ftp

  Both of them have a little request data and a much bigger answer size,
  so satellite works very well with it, but with a big time of answer,
  this is the biggest problem of satellite connection (consider a
  typical Sat distance, like 36.000 km, so you would have a time access
  of [ 36000 km / 300.000 km/s = 0.120 s = ] 120 ms you have to add (2
  times, cause first ISPs server send it to, then you download it from)
  to classical Internet time access.

  Recently ISP allows their clients to use also other kind of service,
  like



  �  Chat

  �  Email

  �  News

  and many others.

  There exist also services called "one-way", which consist in mail
  service , download on-demand (where you make a file reservation to be
  scheduled at some time) and site download: these services are offline,
  so you can access to them without modem (or other kind of) connection.

  2.3.  Other technologies

  We have to report another satellite technology: the 2-way sat
  connection.  It uses only the parabolic antenna to contact Internet in
  both 2 directions.  Its cost is much higher that 1-way connection. We
  expect something from it for immediate future, for now it allows a
  bandwidth of 4 Mbit/s in download and 256Kbit/s in upload.

  2.4.  What is the max bandwidth?

  It depends on many factors: ISP purpose, TCP window used, applications
  used by the client and the more important of all, "Internet
  congestion".

  You can expect a max bandwidth of 1-4 Mbps and a average of about
  10-30 KBytes/s, but I repeat, it depends on many factors.

  Anyway some ISPs tell you they give you a "Max" bandwidth, while the
  average bandwidth could be very lower, due to intra-ISP congestion.

  Some other ISPs guarantees you to have a "Minimal" bandwidth, which is
  more meaningful than "MAX", cause it is available all the time.

  Please see Appendix A for more about get downloading performance
  better.

  2.5.  How much does it cost?

  We have to distinguish between hardware costs and account costs, the
  first are known, while the second depend on which service you choose
  ("guaranteed"/"not guaranteed", what bandwidth).

  2.5.1.  Hardware costs

  To install our little satellite system we need:

  1. Sat card

  2. Parabolic antenna

  3. one or more feed (converter)

  Noticed that we need a digital converter to use Internet via
  satellite.

  Sat card costs depends on brand you choose, about 200US$-300US$.

  Parabolic antenna is about 50 US$.

  Converter is about 50US$.

  So we have about 3-400 US$ of hardware cost (maybe you still have to
  add installation cost!!).

  If you want also receiver Crypt service:


  1. CI is about 100 US$.

  2. CAM is about 100 US$-250 US$.

  2.5.2.  Account costs

  Here costs depend on what ISPs give you access, what's peak bandwidth,
  if there is a guaranteed bandwidth (which is more important than peak
  one), what kind of service they give you and so on.

  Also some ISP gives you free access in change of viewing an always
  foreground spot banner (you cannot iconize it!!): in this case you
  will pay when you'll go to buy something showed in banner!!

  Typically account costs are about 100-150 US$ at year for "not
  guaranteed" services and 4-600 US$ or more for guaranteed ones (they
  guarantee you a minimal bandwidth you can use also under congestion
  moments, obviously intra Sat-ISP congestion!! When you go out to
  Internet nobody can guarantee you anything!!).

  2.6.  What are the satellites used?

  When we speak about satellites we mean: Astra (19.2 degree SE),
  Hotbird (13.2 degree SE), new Europestar (45 degree SE), Eutelsat (8
  degree SW), Astra (26E), ArabSat 3A (26E).

  2.7.  What ISPs give Sat Internet Access?

  In Europe we know about 8 ISPs giving Sat access for Internet:


  1. EuropeOnLine - EON <http://www.europeonline.net>

  2. Netsystem <http://www.netsystem.com>

  3. Starspeeder <http://www.starspeeder.com>

  4. Sat Node <http://www.satnode.com>

  5. Eliosat <http://www.eliosat.com>

  6. Falcon Stream  <http://www.falconstream.com>

  7. SkyDSL <http://www.skydsl.com>

  8. OpenSky <http://www.opensky.it>

  9. DirecPC <http://www.direcpc.com> but this use a proprietary sat
     card (this is a first Sat ISP )

  10.
     http://www.xanticbroadband.com/ <http://www.xanticbroadband.com/>

  EON gives access for about 150 US$ at year without guaranteed
  bandwidth.

  Netsystem offers its services at "null cost", you just have to see its
  banner.


  Starspeeder gives access ???

  Eliosat costs 350 US$ at year with a 128 Kbps guaranteed (minimal
  service, see web site for more);in addition it gives 2-way technology
  access for either receive and transmit.

  SkyDSL gives access full-time and it costs about 15 US$ at month with
  128Kbit/s bandwidth, but it allows a bigger bandwidth where you pay
  each Mb downloaded (you can select from 256Kbit/s up to 4Mbit/s), for
  more you can visit its web site.

  IMPORTANT : before subscribing some satellite account, please verify
  "foot of Satellite" and diameter of parabola.

  OpenSky started before summer 2001 in its "beta test": it allows you
  to try the sat service downloading at maximum 300 MB at month (free).
  To register you need to go at OpenSky registration procedure
  <http://www.opensky.it/cc/index.asp?f=registrazione.htm> (which is in
  italian language!).

  2.8.  What else?

  With every kind of DVB card you can also receive TV digital channels
  (free channels only) and some cards have support for common interface
  to watch encrypted channel.

  Follows the schema:


  Smart-Card -> CAM -> Common Interface -> Sat Card (with support C.I.)



  CAM Card (there are many standards used for decryption: SECA, IRDETO,
  VIACCESS and others) is the hardware allowing decryption (for TV,
  Radio and Data) while the Common Interface or C.I. (ETSI EN 50221)
  allow connection between CAM and Sat Card.

  3.  Technical Information

  3.1.  General working

  We now try to understand how satellite connection works and at what
  conditions.

  We can imagine a satellite link as a classical Wireless link, I mean a
  link between 2 systems which don't use a real cable to talk each
  other.

  Wireless link is very different from Wired link cause we have some
  additional problems to solve, such as reachability, privacy problems
  and so on. Also there could be weather problems, particularly in snow
  or rain conditions.

  Anyway, we have to consider the first principle behind Wireless
  communication: line of sight free, which is a MUST unless we are
  unable to talk. For more you can see the Wireless-HOWTO
  <http://www.fatamorgana.com/bertolinux/>.

  In sat connections we use a special kind of antenna, a parabolic one,
  that gives us a very high gain in RX, needed to receive satellite
  signal: in fact satellite has a geostational orbital at 36.000 km and
  the only kind of antenna we can use for receiving is just a parabolic
  one.

  3.2.  Frequencies

  Frequency we receive is from 11GHz up to 12.7 GHz (from the satellite
  transponder, the transmitter sending us datas), a very high freq., but
  the feed (converter in the center of the parabola) converts it to, in
  output, 1-2 GHz so that we'll able to send signal to the receiver
  through the cable (up to 40m depending to cable loss).

  3.3.  DVB Receiver Card



  1 GHz Signal --> |RX|--> |ADC| --> |Low Level Network| --> |O.S. TCP/IP Stack|--> Data
                  |____________________________________|
                                  DVB Card



  Now we can imagine a classical RX at 1 GHz receiving analog signals
  from the Sat, converting it to digital signals and giving all to the
  low level network layer (ISO OSI 1,2): here, card firmware builds a 2
  level packet (pretty like ethernet) to be sent to our PC with Linux,
  Windows, or other system, and in the end, we will only have to
  transform it to a TCP/IP packet.

  3.4.  Data Link Level DVB setting

  Here we have to config some settings, directly to the DVB card:


  1. Frequency working, we have to set the satellite frequency (as from
     magazines): it is between 11.8 GHz and 12.8 GHz for example
     12640000 KHz

  2. Symbol rate, measured in symbols per seconds, typically 22 MS/s
     (Mega Symbols per seconds)

  3. Polarization, which is an antenna setting configurable in software:
     possible values are H (Horizontal) or V (Vertical).

  4. PIDs. The PID is used for select a trasmission between many signal
     from same frequency.

  5. Also we have to specify the bitfilter mask, which tells us how
     large is the destination MAC addresses group (bitfilter mask is
     similar to TCP/IP netmask, the only difference is that the
     bitfilter mask is 48 bit size while TCP/IP netmask is 32 bit size).
     Always Internet data is sent with Unicast PID, while Video always
     is sent using Multicast PID .

  6. Calculate MAC address: here we specify what will be our MAC address
     (for our DVB card). You need to do this cause some ISP uses an
     algorithm (see Appendix A for more) which calculates your MAC
     address from your IP address, some other ISP uses your own MAC
     address.

  3.5.  TCP/IP working

  As we said in 2.2 section, first we have to make a request using the
  modem interface (i.e. ppp0 or whatever we use to reach Internet), then
  the answer will return to our DVB interface (dvb0).

  Modern O.S. allow us to receive packets from an input interface,
  different from the output interface from where we made the request: to
  do it we have to "disable" some packets flow control, such as type an

  echo "0" > /proc/sys/net/ipv4/conf/dvb0/rp_filter (for Linux).

  3.6.  Authentication

  It remains only one thing to complete our description: authentication
  method.

  Some Sat ISPs use the so called "Proxy Authentication": when you used
  their proxy, you also need to give login and password to continue the
  request (you should have been subscribed some kind of account to use
  their sat service): once done, the ISP use your IP address to
  calculate your MAC address (see Appendix A for more), to which send
  the answer.

  Some other ISPs require you make a VPN connection (using your login
  and password) first, then they will control your registration account
  (where they retrieve your MAC address) and will send data directly to
  (and only to) your card (your MAC address).

  Anyway noticed that you can modify your dvb sat filter value to be
  able to receive packets destined to EVERY mac address (related to a
  single frequency).

  3.7.  Services I can use with a sat connection

  Typically services you can have from sat connections depend on what
  authentication system is used by ISP:


  �  with classical "Proxy Authentication" you can only use HTTP and FTP
     service, while

  �  with VPN connection you have (ideally) no limit to services you can
     use, the only limit is decided by RTT (time access) to satellite,
     about 500-1000 ms average: so you can forget to use "Voice" or
     other "Real Time" services!! (see VoIP-HOWTO
     <http://www.fatamorgana.com/bertolinux> for more). Anyway you still
     can use: mail, chat, telnet, ping, dns and so on.

  4.  Requirements

  Here we will see what we need to try a Sat system.

  4.1.  Knowledge requirement

  For this trying you need some experience in internetworking under
  Linux (as from Net-HOWTO <http://www.linuxdoc.org/HOWTO/Net-
  HOWTO/index.html>) and a very little of practical experience with
  parabolic antenna and sat systems (you should be able to pointing out
  your antenna, with right angles).


  4.2.  Hardware

  We need:


  1. Parabolic antenna, also taken from an analog system.

  2. Digital converter to be placed in the middle of the antenna.

  3. Receiver card DVB compatible.

  4. a PC to connect to.

  4.3.  Software

  Here you need a


  1. driver for the DVB card working under your O.S. (Linux, Windows or
     other).

  2. right setting to use it

  3. external application in some cases (such as VPN-PPTP client for ISP
     like Netsystem or Starspeeder).

  For the software under Linux you can found the Siemens DVB driver at
  Linux TV Project <http://www.linuxtv.org>.

  4.4.  TV Software

  There is also some Video software used to implement TV reception:

  4.4.1.  Under Windows


  1. MultiDec MultiDec 6.6b
     <http://www.erkner.com/free/digi/MultiDec66b.zip> (free with source
     code)

  2. TPREdit TPREdit <http://come.to/uhura> (for Technotrend)

  3. WinTV DVBs Hauppauge <http://www.hauppauge.de/software.htm> or
     Technotrend <http://www.technotrend.de>(for Siemens compatible
     card, Hauppauge, Technotrend, Technisat, etc... )

  4. WinDVB2000 WinDVB2000 <http://www.odsoft.org/english.html> (about
     19$).

  4.4.2.  Under Linux


  1. gVideo is an application included in Siemens driver

  2. Vdr Video Recoder (good for watch TV)

  5.  Base setup

  5.1.  First: mounting

  The first thing we have to do is to mount our parabolic antenna;

  After we need to pointing it out (searching right degrees from some
  magazine): degrees are always intended from south to east or to west
  for horizontal one and from ground to satellite line for vertical one.
  Classical pointing tools is the compass.
  5.2.  Calibrating

  How can we see if we are right oriented?

  After decided a right range of angles, we have to adjust it measuring
  power level. For such a thing we can


  1. Use for example an analog receiver (which is compatible with
     digital converter) and start to search right degree: when we see
     some imagine we'll get it. I suggest to use analog converter cause,
     maybe, you have one (from precedent installation) and cause it is
     more simple to calibrate it than digital one.

  2. Use a power meter (about 20US$) with sequential lights: at full
     signal all lights turn up.

  5.3.  Double Feed

  You can also install a double feed system (some vendors sell a
  complete kit with standard distance to receive, for example, Astra
  (19.2 SE) with Eutelsat (16 SE) or with HotBird (13 SE).

  For mounting it you have to consider, in addition, that satellite is
  at the opposite side of the converter, like in figure:


                SAT1                 SAT2
                   \                 /
                    \               /
                     \   C1   C2   /
                 \    \    \ /    /     /
                  \    \   / \   /     /
                   \____\ /___\ /_____/

                        Top View

                 C1 receives from SAT2
                 C2 receives from SAT1



  Also, with 2 focus, you would use a diseq.

  5.4.  Data-link level adjusting

  Once we got analog signal we have to adjust our receiver to right
  frequency, PID, speed rate and so on.

  I report here an example of configuration, for EON (EuropeOnLine),
  transponder 114 on Astra satellite (19.2 SE)

  Frequency: 12640 MHz

  Polarization: V (Vertical)

  Symbol Rate: 22000 KS/s

  PIDs:


  �  Unicast: 512 (decimal), 0x200 (hexadecimal)

  �  Multicast: 785, 786, 1041 (decimal), 0x311, 0x312, 0x411
     (hexadecimal), but you should notice that, in many cases, Multicast
     PIDs are taken in automatic.
  We also need another info: what MAC address to assign to our DVB card.


  Again, for EON you can see Appendix A to calculate MAC address from
  dynamic IP address.

  Obviously you need login and password to use ISP service.

  6.  Configuration under Linux

  In this section I will assume to use a Siemens compatible card, like
  an Hauppage WinTV DVB card, for such cards you can download drivers
  from LinuxTV <http://www.linuxtv.org/download/dvb> or DVB-s PCI cards
  under Linux <http://www2.arnes.si/~mthale1/index.html >.

  Unfortunately there are no drivers (at this moment) for SkyStar2
  (Netsystem card) for Linux!

  6.1.  Drivers installation

  Once downloaded drivers, you have to untar them to a directory, enter
  it and type "make" and "make insmod". To do this you need to have
  actual kernel sources under /usr/src/linux (unless, download them from
  http://www.kernel.org <http://www.kernel.org> and recompile them).

  After made "make insmod", your system should have DVB modules loaded.
  To unload them type simply "make rmmod".

  6.2.  Setting up /etc/dvbd.conf

  /etc/dvbd.conf file is used to setup data-link parameters for your DVB
  card. Here main settings:


  �  "power", which indicates the power to LNB, 1=ON, 0=OFF. Usually you
     should set it to 1, unless you do some kind of cascade between more
     than 1 LNB.

  �  "symbolrate", this is the symbol rate per seconds, for example
     22.000.000.

  �  "frequency", at which receiving datas, like 12.640.000.

  �  "ttk", the 22 kHz signal, almost always to 1.

  �  "diseqc", used to control the diseq, (it means only when you have a
     diseq controlling 2 or more converters) 0 if none.

  �  "AFC", usually set to 1.

  �  "polarization", 1 for horizontal or 0 for vertical one.

  �  "filter_n <PID> <MAC> <BITFILTER>", where n is intended 0 for
     Unicast and 1-9 for Multicast; PID is expressed in decimal form,
     MAC is the MAC address only valid for Multicast filter and
     BITFILTER is a number which bits represent bytes to mask (for
     example 10 = 2 (bit 1) + 8 (bit 3), so mask will be 00 00 FF 00 FF
     00).


       Example


  ------------------------------------------


  # DVB receiver configuration file, (c) 2000 data planet international

  # standard location in /etc

  # LNB power on=1/off=0

  power 1

  # symbol rate [symbol/sec]

  symbolrate 22000000

  # ASTRA TR 114

  frequency 12640000

  # 22 kHz signal on=1/off=0

  ttk 1

  # diseqc on=1/off=0

  diseqc 0

  # AFC on=1/off=0

  AFC 1

  # polarisation H=1/V=0

  polarisation 1

  # settings for MPE filter, PID and MAC filtering, valid MAC bytes

  filter_0 512

  filter_1 785 00:D0:5C:1E:96:01 48

  filter_2 786 00:D0:5C:1E:96:01 48

  filter_3 1041 00:D0:5C:1E:96:01 48

  -----------------------------------------

  filter_0 has no MAC and no bitfilter values cause the right MAC
  address is calculated from IP address (see Appendix A). We will see
  this setting is OK only for some ISP, for others we'll have to change
  dvbd.c

  6.3.  Dvbd daemon

  Once your /etc/dvbd.conf is ok, you can launch dvbd application,
  which, if executed without -d option, write to stdout signal quality
  level:


  �  Sync MUST be 127 or near it

  �  Vber MUST be 0

  unless you are not well receiving from Sat (check cable and/or dish
  pointing).

  Note:


  Maybe you have to change, in dvbd.h this line

  #define network_device "eth0"

  to

  #define network_device "ppp0"

  depending on which interface you use to reach Internet, eth0 or ppp0:
  type "make" to update binary file and restart dvbd.

  6.4.  How to config EON service

  Now you have a good signal, you can try to use some sat service.

  For EON go at "proxy" setting in Netscape preferences and set under
  HTTP and FTP:

  proxy.xxx.europeonline.net

  and, in "port" 8080 and FTP proxy with "port" 8090.

  where xxx is the transponder number (103,113,114 or 115) you are using
  (see Appendix B for more).

  Now you should be able to navigate wherever you want.... Good
  navigation.

  To share EON service with many clients you can use Squid proxy
  <http://www.squid-cache.org> application, enabling cascade to EON
  proxy.

  For a more complex use of EON, like more complex cascade proxy or
  sharing users, see EON Linux Masquering FAQ Page
  <http://obiwan.hvrlab.org/~faz/eon/eon_masq.html>

  6.5.  How to use Netsystem service

  Netsystem service is a little more complicated than EON under Linux,
  cause, in addition, you need to setup:


  1. VPN connection

  2. patch for pppd (needed only if using pppd <= 2.4.0)

  3. routing settings with simple scripts

  4. patch for dvbd.c

  5. Test it

  6. Get performance better

  7. Sharing Netsystem with many clients

  6.5.1.  VPN connection

  First you need to download VPN PPTP client application
  <http://cag.lcs.mit.edu/~cananian/Projects/PPTP/>.

  After untared, compiled and installed it, you should add an entry to
  your /etc/ppp/pap-secrets and /etc/ppp/chap-secrets files, like that:

  "login" * "password" *

  where "login" and "password" are the same according to Netsystem
  registration <http://css.netsystem.com>.

  6.5.2.  Patch for pppd

  As described at PPTP description
  <http://www.sigpipe.org/~me/vpn/pptp.html>, you need to patch your
  pppd daemon to support connection with Netsystem VPN server (Linux
  server).

  Warning: using pppd version >= 2.4.0 you don't need pppd patch.

  So you have to:


  1. download a recent pppd version
     <ftp://cs.anu.edu.au/pub/software/ppp/>

  2. download and gunzip the correspondent patch for pppd from Here
     <ftp://ftp.binarix.com/pub/ppp-mppe/>

  3. untar pppd in a directory

  4. type "patch -p0 < patch_name"

  5. enter pppd directory

  6. type "make", "make install"

  6.5.3.  Routing settings

  Now your pppd will be able to working with:

  "pptp vpn.netsystem.com debug user <login>"

  where <login> is your login account from Netsystem: you should see, in
  log file (/var/log/messages) ppp1 connection debug info.

  If all is ok you should see ppp1 interface with "ifconfig" command.

  If you still have problems on authentication, please add a "noauth"
  line to your /etc/ppp/options file.

  Once ppp1 interface is up, you should do the following:


  1. type "ifconfig ppp1" and find the IP address (I will call IP) on
     the right of "P-t-P:" string.

  2. delete it from routing table with "route del IP"

  3. add it to ppp0 interface with "route add IP dev ppp0"

  4. delete default gateway from ppp0 with "route del default"

  5. add default gateway to ppp1 with "route add default dev ppp1"

  Points 1-3 are requested cause point-to-point interface are managed,
  under Linux, adding the gateway to the new interface (which is not a
  good idea in this case): unless it you will have a endless loop, cause
  your packet will be continuously encapsulated on itself.

  Points 4,5 are used to make "all internet requests" to ppp1 interface,
  so we'll reach the "world" by using VPN connection: this could be not
  optimal in some condition, for example for DNS queries, which could be
  sent directly to avoid useless Sat delay time.
  Instead of manually setup routing configuration you can try using
  these little scripts:

  "netsystem.on" script

  ______________________________________________________________________


  route add IP_DNS1 dev ppp0

  route add IP_DNS2 dev ppp0

  route add -net 212.31.242.0 netmask 255.255.255.0 dev ppp0

  pptp vpn.netsystem.com user <login>

  /bin/sleep 5

  route add default dev ppp1

  ______________________________________________________________________


  "netsystem.off" script

  ______________________________________________________________________


  route del IP_DNS1 dev ppp0

  route del IP_DNS2 dev ppp0

  route del -net 212.31.242.0 netmask 255.255.255.0 dev ppp0

  kill -9 `ps x|grep "pppd"|grep "<login>"|grep -v "ps"|tr " " "\n"|head
  -n 2`

  rm --force /var/lock/LCK..tty*

  rm --force /var/run/pptp/*

  rm --force /var/run/ppp1.pid

  killall -9 pptp

  ______________________________________________________________________


  IP_DNS1 and IP_DNS2 are ip addresses of your dns servers (primary and
  secondary).


  <login> is the login name of your Netsystem account.

  I tried it out under kernel 2.4.6 RedHat 7.1 and it works very well
  (without any problems about ppp1 endless loop or similar).

  This line:

  kill -9 `ps x|grep "pppd"|grep "<login>"|grep -v "ps"|tr " " "\n"|head
  -n 2`

  is used to find PID of pppd process talking with VPN server (ppp1
  interface): notice that you cannot just only type " killall pppd"
  cause your ppp0 interface also would go down.

  6.5.4.  Patch for dvbd.c

  After solved problems about PPTP you have to change some line in
  dvbd.c, near the end of it:


  if (strcmp (v, "filter_0") == 0) { if (s != NULL) { unsigned char ip[4];
  dvbcfg[0].status = ON ;
  dvbcfg[0].filter.data[0] = 0x3eff ;
  dvbcfg[0].filter.pid = (__u16) atoi (s) ;
  dvbcfg[0].filter.mode = 0x0c ;
  if (ipget (ip, network_device)) { fprintf(stderr,"Can't get local ip address. Stop.\n") ; return -1 ; }
  syslog (LOG_NOTICE, "Local ip is %u:%u:%u:%u\n", ip[0], ip[1], ip[2], ip[3]);
  dvbcfg[0].filter.data[1] = (ip[3] << 8) | 0x00ff ;
  dvbcfg[0].filter.data[2] = (ip[2] << 8) | 0x00ff ;
  dvbcfg[0].filter.data[6] = (ip[1] << 8) | 0x00ff ;
  dvbcfg[0].filter.data[7] = (ip[0] << 8) | 0x00ff ;
  dvbcfg[0].filter.data[8] = (0x02 << 8) | 0x00ff ;
  dvbcfg[0].filter.data[9] = (0x00 << 8) | 0x00ff ;
  setmac (ip) ; }
  else { dvbcfg[1].status = OFF ; } }



       Now following lines:


  dvbcfg[0].filter.data[1] = (ip[3] << 8) | 0x00ff ;

  dvbcfg[0].filter.data[2] = (ip[2] << 8) | 0x00ff ;

  dvbcfg[0].filter.data[6] = (ip[1] << 8) | 0x00ff ;

  dvbcfg[0].filter.data[7] = (ip[0] << 8) | 0x00ff ;

  dvbcfg[0].filter.data[8] = (0x02 << 8) | 0x00ff ;

  dvbcfg[0].filter.data[9] = (0x00 << 8) | 0x00ff ;


       will be changed to


  dvbcfg[0].filter.data[1] = (MAC[5] << 8) | 0x00ff ;

  dvbcfg[0].filter.data[2] = (MAC[4] << 8) | 0x00ff;

  dvbcfg[0].filter.data[6] = (MAC[3] << 8) | 0x00ff ;

  dvbcfg[0].filter.data[7] = (MAC[2] << 8) | 0x00ff ;

  dvbcfg[0].filter.data[8] = (MAC[1] << 8) | 0x00ff ;

  dvbcfg[0].filter.data[9] = (MAC[0] << 8) | 0x00ff ;

  Where MAC[0]:MAC[1]:MAC[2]:MAC[3]:MAC[4]:MAC[5] is our MAC address
  (according to Netsystem registration).

  For example, using the address 00:d0:d0:d0:d0:d0 we'll have:

  dvbcfg[0].filter.data[1] = (0xd0 << 8) | 0x00ff ;

  dvbcfg[0].filter.data[2] = (0xd0 << 8) | 0x00ff;


  dvbcfg[0].filter.data[6] = (0xd0 << 8) | 0x00ff ;

  dvbcfg[0].filter.data[7] = (0xd0 << 8) | 0x00ff ;

  dvbcfg[0].filter.data[8] = (0xd0 << 8) | 0x00ff ;

  dvbcfg[0].filter.data[9] = (0x00 << 8) | 0x00ff ;

  notice hexadecimal notation 0x??

  After, you have to type "make" and use the new dvbd created.

  Note: to successfully patch the dvbd.c you need to use dvb driver
  version >= 0.8.2, cause older versions have some instability problems.

  6.5.5.  Test it

  Finally, we can test Netsystem under Linux. We can make a "ping
  www.somehostpingable.com" and check the response time: it should be
  between 400 and 2000 ms.

  If you still have problems, you should control if all is OK with VPN
  interface:


  1. open your preferred network sniffer (for example Ethereal
     <http://www.ethereal.net>) and starts to analyze "ppp0" interface
     (ppp0, not ppp1!!)

  2. make a ping

  If VPN is ok you should see 2 (or maybe 1) GRE-Encapsulated packets
  each second, endless. If you cannot view anything your VPN is not
  correctly working: stop it and restart it.

  6.5.6.  Get performance better

  Once you setup all things you NEED to use (particularly with Netsystem
  service) some "download accelerator" to get performance better: please
  see Appendix A for more.

  6.5.7.  Sharing Netsystem with many clients

  To do this you can enable "IP Masquering", allowing your client to use
  VPN like a normal Internet interface; main problem is that our
  satellite connection is very good for download while it has bad
  performance for just browsing web pages (or other service more
  interactive than downloading).

  You can think to use Squid proxy <http://www.squid-cache.org> or Socks
  proxy <http://www.socks.nec.com/>, but you don't solve your problems,
  cause even now ALL your request would be forwarded to same interface,
  VPN.

  The solution is to use 2 routing tables, one using direct line
  interface and the other using VPN one. So you can do like this:


  1. be sure of have installed "iproute2" commands (for example type
     "ip" on shell and control if it tells you something), for more see
     Linux 2.4 Advanced Routing HOWTO
     <http://www.linuxdoc.org/HOWTO/Adv-Routing-HOWTO.html>.

  2. be sure of have started Netsystem service and annotate ppp1
     interface IP address, we'll call it LOCALIP.

  3. type: "echo "210 sat" >> /etc/iproute2/rt_tables", to more
     comfortable call "sat" rule 210

  4. type: "ip rule add from LOCALIP table sat", to create table "sat"
     relative to all requests coming from LOCALIP IP address.

  5. type: "ip route add default dev ppp1 table sat", to send all "sat"
     requests (see above) to ppp1 interface.

  6. if you use Socks proxy <http://www.socks.nec.com/> be sure to set,
     in sockd.conf file, "external" to LOCALIP.

  7. if you use Squid proxy <http://www.squid-cache.org> be sure to set,
     in squid.conf file, "tcp_outgoing_address" to LOCALIP.

  Once done all that, you will notice to have 2 kind of working: without
  any proxy your clients will ask to direct line, while by using proxy
  (squid or sockd) the request will be forwarded to VPN interface and,
  definitely, toward satellite.

  Notice that maybe you wish to use sockd instead of squid, cause
  satellite requests are typically used for download (while squid is
  typically used for browsing...).

  What happens with iproute2 commands is that, when you ask for an
  address to sockd or squid, relative proxy (using IPLOCAL IP address,
  bound at run-time by proxy network daemon) request enters the TCP/IP
  stack where kernel will forward it (thanks to point 4 above) to sat
  table and, definitely (by using point 5) to ppp1 interface. All other
  rules will be forwarded to classical default route (I mean across ppp0
  interface or whatever other interface for direct Internet).

  6.6.  How to use Sat Node service

  You have to follow all instructions as for Netsystem.

  Before enabling VPN connection, you need to type:


  �

  �  vpn server just through ppp0

  �

  �  to reach every place.

  What really changes from Netsystem is that, we don't force VPN gateway
  (212.56.224.34, IP on the right of ''P-t-P'' in ppp1 interface) on
  ppp0 interface, but we force another IP (212.56.224.36). All other
  things should not change.

  Thanks to Ricardo Santiago Mozos and Norberto Garcia Prieto.

  6.7.  OpenSky service under Linux


  1. You need to register at Opensky Registration site
     <http://www.opensky.it/cc/index.asp?f=registrazione.htm>. You'll
     receive a confirming email with login and password in few days.

  2. After you have to go to https://sdr.eutelsat.net
     <https://sdr.eutelsat.net> and enter login and password data to
     connect.


  3. Set the proxy: ''proxy.eutelsat.net:8080''.

  It is strongly suggested to use downloader applications (see Appendix
  A for more) to get performance better.

  OpenSky is the latest satellite service and it offers 300 MB at month
  (for free).

  Configuration is pretty like EON service, you have to use 0.8.2
  siemens drivers you download from LinuxTV
  <http://www.linuxtv.org/download/dvb>, then you NEED to patch dvbd
  applications.

  To apply the patch and to test OpenSky you can find useful infos at:


  �  http://members.tripod.com/andrei_b/linux/dvbd/dvb-app-dvbd.htm
     <http://members.tripod.com/andrei_b/linux/dvbd/dvb-app-dvbd.htm>

  �  http://pguiral.free.fr/DVBS/opensky.html
     <http://pguiral.free.fr/DVBS/opensky.html>.

  7.  Configuration under Windows

  7.1.  EON

  Hauppage WinTV has DVB-DATA application that allows to specify data-
  link settings.

  7.2.  Netsystem

  First you need to install VPN capabilities.

  In addition you need to download Netsystem software (always foreground
  spot banner) and launch it: after you should not be able to use
  Netsystem service: you can download it from here
  <http://bertolinux2000.interfree.it/Netsystem/Netsystem.zip>

  7.3.  OpenSky

  See Linux.

  8.  Appendix A - Notes

  8.1.  Translation Dynamic IP -> MAC Address

  The translation used by some ISPs to calculate MAC address (which need
  to have your DVB card to receive their packets) is:

  00 : 01 : IP[0] : IP[1] : IP[2] : IP[3]

  where

  IP[0].IP[1].IP[2].IP[3] is your dynamic IP address.

  This feature is used, for example, by EON.

  8.2.  TCP Window

  Satellite connections are an interesting example of very high RTT
  (round trip time, access time): another example is the Mars - Earth
  communication or also the Moon - Earth one.

  These connections have a very bad feature: very low interactively.


  Typical network (or digital, generally) connections use the so called
  transmission "window", which represents the data buffer can be sent
  before waiting for an answer. In TCP/IP protocol stack this is the TCP
  Window.


                    ----------------------
    | - - - - - - - > can continue |-|-|-|---->
    |               ----------------------
    |             Buffer sendable before confirm
    |
    | - - - - - - - <----------------------
                     Confirmation Answering



  Now, if our communication has an high access time and if we had a
  little TCP Window we would lose very much time only waiting for the
  data confirmation (ACK), so the real bandwidth would decrease (for
  example if you have a 16KB TCP window, typical of Windows systems and
  a RTT of 400 ms, you cannot overcome 16KB/0.4 = 40 KB/s)

  Solution is to use a very high TCP Window (such as 256 KB or some MB).

  Unfortunately, under many systems, is not so simple to have a great
  TCP Window, so, in latest years, it starts to appear new applications
  ("download accelerators" described in next section) that split in many
  pieces a file and download all them in the main time: this is just
  equivalent to download only one file with a single piece size,
  avoiding the RTT problem.

  8.3.  Download accelerator

  We report here some useful link to so called "download accelerator"
  which is an application that does 2 things:


  1. resuming session management, it allows stopping downloading and
     restarting later (this can be done thanks to "resuming feature"
     introduced in Http and Ftp server, which allows you to specify at
     what byte number start to download).

  2. splitting, divide the file in many pieces and let them start in a
     multithreaded fashion.

  As we saw in the previous section, a download accelerator allows us to
  increase satellite bandwidth.

  8.3.1.  Under Linux


  �  Aria <http://aria.rednoah.com/>

  8.3.2.  Under Windows


  �  FlashGet <http://www.amazesoft.com>

  �  GetRight <http://www.getright.com>

  �  Mass Downloader <http://www.metaproducts.com>

  9.  Appendix B - Well Known Sat ISP setting value



  9.1.  EuropeOnLine

  EON sends data from Astra satellite (19.2 SE).

  MAC address is calculated from IP address (see Appendix A).

  It uses "Proxy Authentication".

  Follows the 4 transponder setting:

  9.1.1.  Transponder 113


  �  Frequency: 12633.250 MHz,

  �  SRate : 22 MS/s

  �  Polarization: Horizontal

  �  Unicast PID: 512 (decimal)

  9.1.2.  Transponder 114


  �  Frequency: 12640 MHz,

  �  SRate : 22 MS/s

  �  Polarization: Vertical

  �  Unicast PID: 512 (decimal)

  9.1.3.  Transponder 115


  �  Frequency: 12662.750 MHz,

  �  SRate : 22 MS/s

  �  Polarization: Horizontal

  �  Unicast PID: 512 (decimal)

  9.1.4.  Transponder 103


  �  Frequency: 12461 MHz,

  �  SRate : 27.5 MS/s

  �  Polarization: Horizontal

  �  Unicast PID: 512 (decimal)

  9.2.  Netsystem

  Netsystem uses Astra satellite (19.2 SE) to send data .

  MAC address used is your real MAC address DVB card.

  It uses VPN connection.

  Follows data setting:



  9.2.1.  Transponder 119


  �  Frequency: 12721 MHz

  �  SRate: 22MS/s

  �  Polarization: Horizontal

  �  Unicast PID: 451 (decimal)

  9.3.  Sat Node

  Sat Node uses Astra satellite (19.2 SE).


  �  Frequency: 12603.750 MHz

  �  SRate: 22MS/s

  �  Polarization: Horizontal

  �  Unicast PID: 302

  9.4.  Open Sky

  Open sky uses Eutelsat satellite (7 SE).


  �  Frequency: 11262 MHz

  �  SRate: 27.5MS/s

  �  Polarization: Horizontal

  �  Unicast PID: 3003

  10.  Links

  10.1.  Open

  http://www.linuxtv.org <http://www.linuxtv.org>

  http://www.fatamorgana.com/bertolinux
  <http://www.fatamorgana.com/bertolinux> http://www.hack-it.net/How-
  To/Sat-HOWTO.html <http://www.hack-it.net/How-To/Sat-HOWTO.html>

  10.2.  Commercial

  EuropeOnLine - EON <http://www.europeonline.net>

  Netsystem <http://www.netsystem.com>

  Starspeeder <http://www.starspeeder.com>

  Sat Node <http://www.satnode.com>

  Eliosat <http://www.eliosat.com>

  Falcon Stream  <http://www.falconstream.com>

  SkyDSL <http://www.skydsl.com>

  OpenSky <http://www.opensky.it>


  DirecPC <http://www.direcpc.com>

  http://www.xanticbroadband.com/ <http://www.xanticbroadband.com/>

  http://www.fatamorgana.com <http://www.fatamorgana.com>







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