TiVo Community Forums Archives - Debugging Update over Ethernet

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Debugging Update over Ethernet
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Posted by: BBreneman

I'm so close I can taste it...All of the PPP over serial connection stuff is working great, rsync, telnet, etc. During the daily call process, tivo is defaulting to the existing ppp connection and sending its http POST. However, it cannot seem to connect - after about 10 minutes it fails. I have tried the test call with the same results.

Here's my config:

Tivo connected via PPP over serial to a RedHat Linux 7 box
Tivo IP 192.168.1.98
Redhat box IP for PPP is 192.168.1.97
Redhat box IP for ethernet is 192.168.1.99
All are connected to the net via a Linksys router (at 192.168.1.100)and (finally) a cable modem

Telnet to the TiVo works
rsync works back and forth between the linux box and the tivo

I don't think TiVo can find a route to the internet, though. I'm new to linux, but am learning the tricks as fast as I can. Does anyone recognize this problem, or have any thoughts on how to debug it?

Many thanks in advance!

Posted by: jack

one thing to check. Look at
/proc/sys/net/ipv4/ip_forward
and make sure it has a 1. If it's 0, then your box won't forward
between eth0 and ppp0. do a
echo "1" > /proc/sys/net/ipv4/ip_forward
to fix it. I have
echo "1" > /proc/sys/net/ipv4/ip_forward
in my /etc/rc.d/rc.local file because I can't figure out
how your supposed to set it otherwise.

You also probably need proxyarp as part of your ppp settings
on the linux box. Your NAT/Firewall/thingie might not know
that your tivo is connected to your linux box. The proxyarp
think should fix that.

------------------
jack

Posted by: omv

If 192.168.1.x is your internal subnet including other computers and somethhing else is already doing ipmasquarading, you'll want to do proxyarp as a ppp option. Originally I gave my tivo one of my static IP addresses to get it working. IP forwarding also needs to be turned on as jack stated.

If 192.168.1.x is ONLY for the tivo-ppp, then you'll want to turn on masquarading instead. Below is my ppp script which fires it all up - note, there's probably more secure firewall rules for general use but this should work and prevent people from using your machine to masquarade their own packets.

/usr/sbin/pppd ttyS1 115200 asyncmap 0 proxyarp ktune nocrtscts noauth debug kdebug 1 local 192.168.1.10:192.168.1.20
depmod -a
modprobe ip_masq_ftp
echo "1" > /proc/sys/net/ipv4/ip_forward
echo "1" > /proc/sys/net/ipv4/ip_always_defrag
ipchains -M -S 7200 60 160
ipchains -F forward
ipchains -P forward DENY
ipchains -A forward -s 192.168.1.0/24 -j MASQ

Posted by: BBreneman

May I say, you guys rule! Adding proxyarp to my ppp and setting ipforwarding to "1" fixed everything.

These are two things that would be great to add to Franks HOWTO document.

Thanks again!

Posted by: Scutter

It wasn't necessary for me to add proxyarp to my ppp settings on either the linux side or the TiVo side. I currently already have three subnets on my home LAN. Simply adding the serial port PPP just added a fourth subnet. IP Forwarding was definitely necessary, though, but it was already there to support masq-ing for my other subnets. I will be adding a few lines about setting up your linux box as a masqueading gateway, however masquerading and firewalling are both already handled by two other very detailed HOWTO's.

Posted by: jack

quote:
Originally posted by Scutter:
It wasn't necessary for me to add proxyarp to my ppp settings on either the linux side or the TiVo side. I currently already have three subnets on my home LAN.

just might be nice to note if you don't subnet for your TIVO ( I
couldn't and get the firewall/masq/iptables stuff to work ) you
need the proxyarp option.

Also... someone pointed out that your firewall has to allow both
( outgoing ) http and ftp for your tivo box.

------------------
jack

Posted by: omv

One other note:

it might be better to set the ppp-options.cua3 script to use nocrtscts rather than crtscts - this will turn off hardware flow control, and since the serial connection is only a 3 wire interface, there will be no hardware flow control possible.

I had some really crappy rsync times until I turned it off. Maybe unrelated, but no sense setting incorrect options in my book.

Posted by: Scutter

I added the bits about proxyarp and subnetting to the HOWTO, as well as some links to the various linux networking HOWTO's. I'd still like to add some detail about connecting to various Windows-type servers, so if anyone would like to contribute...

FP