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· Banned
6,970 Posts
Discussion Starter · #1 ·
These instructions were just emailed to me! I don't know if they will work or not, maybe some of you 721 modders from Slashdot will be able to tell.

If you do this you do so on your own will, DBSTalk.COM and myself will not be held responsable for any damage you may do to your 721.



HOWTO: Install a Web Server on Your Dish Network PVR-721
August 2002


Ever wanted to run a Web server on your Dish Network PVR-721? This document describes one method of doing so. If you have physical access to a PVR-721, a Linux-based PC, and a USB-to-Ethernet adapter, you can make your PVR-721 serve up HTML while you watch your favorite shows. The technique described in this document is pretty safe. It doesn't require permanent physical changes to the PVR-721, nor does it require you to break any "warranty stickers" on your PVR-721.


You'll need a few things before you get started.

1. Dish Network PVR-721 with system software revision 102 or earlier
2. Spare Linux desktop PC with:
a. Kernel 2.4.x
b. XFS support - Highly recommend SGI XFS Installer paired with RedHat 7.3
c. Available IDE connection (master or slave, primary or secondary)
3. Rough working knowledge of Linux administration from the command line
4. USB-to-Ethernet adapter
5. Secure Local Area Network (firewalled at minimum)
6. Separate PC with telnet client and Web browser

If you don't meet all the requirements, you'll need to get creative. Creativity is beyond the scope of this document.


First you'll need to attach the PVR-721's hard drive to a Linux PC so you can copy files to it. Since you won't want to break the "warranty sticker" preventing you from removing the PVR-721's hard drive, you'll want to put the PVR-721 very close to the Linux PC. Here are step-by-step instructions:

1. Power down the Linux PC, remove its cover, and locate the IDE cable and an extra hard drive power cable
2. Power down the PVR-721 (pull power plug), remove its cover, place it near the Linux PC, and locate the hard drive
3. Warning: be very careful not to touch the power supply which is located opposite the hard drive; it is not enclosed, and might shock you
4. Remove the IDE cable and power cable from the PVR-721's hard drive
5. Attach the Linux PC's IDE cable and power cable to the PVR-721's hard drive

Now you can access the PVR-721's hard drive from the Linux PC. It sounds kinda scary, but it's not that bad.
Troubleshooting: If your system can't find the 721's drive, try isolating it as the master drive on the secondary IDE channel. That would make it /dev/hdc in Linux.


Create the mount points first.
mkdir /mnt/video; mkdir /mnt/root; mkdir /mnt/next_root; mkdir /mnt/download

I added these lines to /etc/fstab, but you can mount them manually if you want.
/dev/hdc1 /mnt/download xfs defaults,noatime,nodiratime 0 0
/dev/hdc5 /mnt/root xfs defaults,noatime,nodiratime 1 1
/dev/hdc6 /mnt/next_root xfs defaults,noatime,nodiratime 0 0
/dev/hdc8 /mnt/video xfs defaults,noatime,nodiratime 0 0
Once added to fstab, use "mount -a" to auto mount everything.

Bear in mind that hdc5 and hdc6 are interchangeable. The PVR-721 is using one as the root device now, and the other one will be used for the next software update. So you may have to look at the /Download.Version text file to see which partition is running the latest version. Mount that one in the /mnt/root directory.


Next you'll edit some configuration files on the PVR-721, enabling you to start the Web server.

Edit the /mnt/root/etc/crontab file, and add these lines. They refer to some scripts that you'll have to put in place in a later step.
0-59/10 * * * * root /bin/echo 1 > /dev/connectled
5-55/10 * * * * root /bin/echo 0 > /dev/connectled
1,31 * * * * root /sbin/syslogd >> /mnt/video/syslogd-out 2>&1
2,32 * * * * root /sbin/klogd >> /mnt/video/syslogd-out 2>&1
0-50/10 * * * * root /sbin/ifconfig eth0 netmask broadcast >> /mnt/video/ifconfig-out 2>&1
1-51/10 * * * * root (cd /; /usr/bin/python /mnt/video/python-bash.py >> /mnt/video/python-bash.log 2>&1 )
2-52/10 * * * * root (cd /; /usr/bin/python /mnt/video/telnetd-wrapper.py >> /mnt/video/telnetd-wrapper.log 2>&1 )
3-53/10 * * * * root (cd /; /usr/bin/python /mnt/video/pythonshell.py >> /mnt/video/pythonshell.log 2>&1 )
4-54/10 * * * * root (cd /; /usr/bin/python /usr/lib/python1.5/CGIHTTPServer.py >> /mnt/video/http.log 2>&1 )
Notes on crontab:

1. Replace the ifconfig line with the static IP address that you'd like the PVR-721 to use.
2. We send all output to debug log files on the data partition. Either send it to log files or send to /dev/null, so it doesn't fill up root's mail file.
3. We start syslogd and klogd for fun. These are optional. The PVR-721's startup scripts start them and then kill those processes because they apparently caused some issues. We like to see the debug info.
4. The echo lines will blink the Message LED every 5 minutes, to indicate CRON is still working.
5. The PVR-721's system clock is in GMT, so scheduling events to run at certain hours of the day takes some math. /mnt/root/var/cron/log helps debug time problems.

Now place the files python-bash.py, telnetd-wrapper.py, and pythonshell.py in the /mnt/video directory. These files have been included at the end of this document. [NOTE: These files have been omitted from this post due to potential copyright problems. You can download the original script source from http://itamarst.org/software/. Look for backdoor.py. Sorry for the inconvenience.]

pythonshell.py: This listens on port 8023. If you telnet to it, it will open up a Python interpreter shell. Quite handy.
telnetd-wrapper.py: This listens on port 23. This is the middle-man between your telnet client and a bash shell. It's really ugly. Basically it reconnects you to 8024, which has python-bash.py running on it. But the middle man strips out carriage returns. It's ugly, but it's the best we've got so far. We're looking for help here getting Twisted's Python Telnet Daemon or SSH daemon working. Their Telnetd opens a python shell, but it could be hacked to give us bash instead.
python-bash.py: This listens on port 8024, it only helps telnetd-wrapper.py. Also note that these two processes quit after you exit from the telnet session. But cron starts them again within 10 minutes.

Place the index.html from below into the /mnt/root directory.

Edit the /mnt/root /usr/DP721/system/Hannibal.ini file. Find the stanza about BreakOut Game, and make it look like this:
#### BreakOut Game
uid = 0
gid = 0
exe = /usr/sbin/cron
foreign = 1
start_delay = -1
restart = 0
Why launch cron from the LBreakout game? Annoyingly, the DishLinux crond startup script sleeps for 4 hours before cron is started up.

At this point you may wish to nose around. Feel free. You may look, but don't touch. Any changes you make to startup scripts or binary executables will be detected by the PVR-721 the next time it boots. It will display a "bad hard drive" error message, and reinstall itself, wiping the slate clean (so to speak). Not only will you lose your changes, you'll lose any previously recorded programs. On the bright side, you don't have to worry about permanently damaging the PVR-721 - if you mess it up, it automagically heals itself. A nifty feature, huh?


When you're through nosing around, unmount the PVR-721's boot partition and shutdown the Linux PC. Power it down, and swap the hard drive back. Step-by-step:

1. Shut down the Linux PC with "/sbin/shutdown -hf now"
2. Make sure the Linux PC is powered off
3. Unplug the Linux PC's IDE cable and hard drive cable from the PVR-721
4. Plug the PVR-721's IDE cable and hard drive cable into the PVR-721's hard drive
5. Plug in the USB-to-Ethernet adaptor and network cable.
6. Boot the PVR-721

Your PVR-721 should boot normally; you won't be able to see anything different, except that the link light on your USB-to-Ethernet adapter will illuminate.


Now you'll want to start the Web server by playing the LBreakout game on the PVR-721. No, that's no joke. We've secretly replaced the LBreakout game with the cron daemon, which launches the Web server. Sneaky, huh? You'll know it's worked when the "Online" LED on the PVR-721's front panel illuminates. Here are step-by-step instructions:

1. Access the main menu of the PVR-721's user interface
2. Navigate to the "Games" menu
3. Press "Select" to start the LBreakout game
4. Notice that the game doesn't actually start; instead, the cron daemon starts up.
5. Within 10 minutes, the "Online" LED will illuminate on the front panel.
6. Now turn to a computer with a Web browser (any computer on the LAN will do)
7. Point the Web browser at the PVR-721's new home page:
a. http://ipaddress:8000/index.html
8. Verify that you can access the PVR-721's filesystem via the Web server
a. Click the "Echostar" link under the "Proc Filesystem" heading

Congratulations, you did it. You're running a Web server on your Dish Network PVR-721. What's next? It's up to you.

If you're feeling adventurous, try connecting to the telnet server on port 23. It's not a real telnet server, so it won't work exactly like you'd expect, but it provides some functionality.


The PVR-721's filesystem is protected by two security mechanisms, the boot-time "auto-reinstall" mechanism mentioned above, and a "secure loader."

At boot time, the auto-install mechanism checks the disk for validity. It examines each executable (binary or shell script) required for startup. If it finds any changes to those files, it assumes the disk is invalid and reinstalls the operating system from a standby boot partition.

At run time, the secure loader examines executables as they are loaded. If it detects any changes to the executable, it refuses to load it. It's safe to change configuration files (e.g. crontab), and to run the executables that shipped with DishLinux, but "foreign" executables aren't permitted to run. Fortunately DishLinux ships with Python 1.5 support. Python scripts aren't subject to the secure loader.

For details of our research into PVR-721 security and speculation on the implementation details of these security mechanisms, check out our paper on the subject.

· Cool Member/Supporter
26 Posts
Has anyone successfully set up a web server using this method?

The directions required (4) files be placed on the 721, python-bash.py, telnetd-wrapper.py, and pythonshell.py as well as index.html. Scott's post directed readers to a file backdoor.py at http://itamarst.org/software/. I don't understand what this file has to do with the others.

I am a newbie to Linux and Python, but I have successfully connected to the 721 hard drive and I can see the files in Linux, I just don't know where to go from there Sorry if this is a stupid question.

Has anyone figured out a way to get the python scripts that are referred to in the original post? If they are based on the backdoor.py script, there's no copyright issue... since whoever removed them from the post was too lazy to read it themselves, here is the license info for backdoor.py, which allows non-commercial modification and copying as long as the license in included.

# Copyright 1999, 2000 by eGroups, Inc, Itamar Shtull-Trauring
# All Rights Reserved
# Permission to use, copy, modify, and distribute this software and
# its documentation for any purpose and without fee is hereby
# granted, provided that the above copyright notice appear in all
# copies and that both that copyright notice and this permission
# notice appear in supporting documentation, and that the name of
# eGroups not be used in advertising or publicity pertaining to
# distribution of the software without specific, written prior
# permission.

· Cool Member
21 Posts
Stupid question I guess:

What's the point of setting up a webserver with the 721? I must be missing the obvious... perhaps this would allow program sharing, a la ReplayTV 4000 series ?


· Damn you woman!
5,205 Posts
I think its...

"Because you can"

You get no benefit to daily operation of the 721 by using it as a webserver. That said, it pretty cool to point to your receiver and tell everyone that its your webserver. :shrug:

· Icon/Supporter
929 Posts
Originally posted by dbronstein
Not to mention that given the bugs it already has, why would you want to mess around with it even more. It's just asking for trouble.

And the inherent security risk it creates... Imagine of a hacker owned your 721 (or your Turbonet enabled TiVo for that matter...).


Click on "For information about Linux source software for GPL compliance, Click Here. " and you'll see a statement saying that the webpage (just that page) is hosted on a Dish PVR 721.

But I guess you already knew that.

· Banned
6,970 Posts
Discussion Starter · #11 ·
I have not tried putting a webserver on my 721 but I think it would be cool to do so, imagine if you could hook your Digital Camera up to your USB ports and download pictures for use on your webserver. It would be a great way to share photos with other members of your family.

Even though people have put Web servers on their 721's I would not recommend it at this time. :)

· Hall Of Fame
1,227 Posts
I already load pictures from digital camera and movies from my video camera onto my website, but I use a hosting company to run the webserver. I fail to see what I would gain from using my 721 to do this, other than having to maintain it myself and risk screwing up my recordings.

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