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OpenWRT PPPoE and IPv6 tunnels

Category: Techie
20 Apr 2020
Written by Andy Hits: 19303

A bit of a techie post for the first time in a while

My current ISP doesn't provide native IPv6, even though I do have a static IPv4 address, so as a project to keep me out of trouble, I thought I'd get my Hurricane Internet IPv6 tunnel up and running.  On the main router on the network, I'm using OpenWRT 19, so I figured this ought to be fairly easy.  Infact, there is documentation on OpenWRT on how to do it with the UI, so I thought it would be a 5 minute job.

When I attempted to follow the steps, it didn't seem to show the 6-in-4 network type, I suspect I'd not got all the dependencies so I did some more looking around, and found the command line example on tunnelbroker.net, and tried that, having ssh-ed into my router.

This still didn't work.  It started assigning my block to devices, but there was no routing on IPv6.  This not being my first networking or routing problem, and with tcpdump already on the router, started to get it listen for packets on various interfaces for packets going to the selected IPv4 tunnel endpoint.  I noticed that packets were not getting replies back. Various firewall IP protocol type suggestions of whitelisting were tried, and still nothing seemed to be getting through

With this in mind, I double checked I could get other devices on the LAN to run IPv6 tunnel, and confirm if it was a NAT or routing issue.

These didn't work immediately, but only started to work when static routes were added for traffic to the tunnel endpoint were added with the next hop on the network.
With a standalone device on the LAN working, I then worked to configure the router with similar settings.  

I've not seen this suggested as a requirement anywhere for getting IPv6 tunnels working, but I suspect that is due to how the network is set up.

The WAN connection is provided as part of UK Fibre Terminated to Cabinet (FTtC).  This uses VDSL2, which there appear to be very few devices that support this and OpenWRT.  So I've got a separate VDSL modem in PPPoE mode, and have been using standard router, with its WAN port configured to dial my ISP over PPPoE. Its not that this is causing anything strange like double NAT, but it seems to have introduced some added complexity to the route table that although the IPv6 is in the WAN firewall zone, it was not then routing the encapsulated IPv6 packets to the IPv4 default gateway.

But with that route in place, IPv6 is fully operational

Mobile Calls in Not-Spot

Category: Techie
14 Dec 2015
Written by Andy Hits: 5054

I'm in the process of moving house, and unfortunately the village it is in is on the edge of a number of different phone companies coverage.

  • O2 has coverage for most of the house, but call quality can vary
  • Vodafone shows it as on the edge of outdoors only
  • EE has nearly no signal downstairs, but some parts upstairs have 3G and sometimes 4G
  • 3 shows as outdoor signal only

I think any other operators are piggybacking on the networks of these 3 so not worth investigating too much

So the solution could be a femtocell.  I've used the Vodafone SureSignal before, and it worked very nicely with its vpn over the ADSL to Vodafone HQ and giving nice solid 3G while in the building
However, we are over 4KM as the crow flies from the exchange, never mind how the copper goes, and the number of junctions degrading the link.  ADSL sync speed is under 500Kb/s, so likely to be far to low for that solution
Fibre to Cabinet is in the village, but because standard broadband is so poor, its fully subscribed most of the time.  It filled up the day that I was trying to organise utilities for the house, so I got stuck with "band" rather than broadband.

Read more: Mobile Calls in Not-Spot

Rebuild Netgear ReadyNAS RAID

Category: Techie
19 Nov 2013
Written by Andy Hits: 32150

Having manually created a secondary array using my spare 500G disks, I found that the Xraid2 setup that my NAS had selected wouldn't expand them with the pair of 1TB already in the array.  You can read more here: Creating Additional Volumes on ReadyNAS

One of the 500's decided to give up the good fight, and I purchased a pair of new 1TB to expand the array  (I keep taking pictures, and 500G didnt seem enough space!)  Adding the first disk into the array and joining it to my manual one wasnt too hard, a quick fdisk to create a compatible partition, then mdadmin --add to include it to the array.  My problem came when I thought I'd be clever, and split my disk batches, so both arrays have a new and an older disk in them. 

I pulled the last 500G from one partition, and 1 of the 1TB in the other, and put the new disk into slot 1 to rebuild the 1TB partition again.

However the readynas just wouldnt rebuild, and no amount of powercycling to try and force a rebuild were helping! It would detect the disk, and the LCD displayed testing disk, and from /var/log/messages I could see various partitionings going on, but no re-sync.

Here's what I did to solve it:

Read more: Rebuild Netgear ReadyNAS RAID

mythtv meta grabber problems

Category: Techie
24 Apr 2014
Written by Andy Hits: 8798

I was on my mythtv media server last night, and I noticed that no matter what I did, I was not getting metadata back when lookups were being done for tv shows recorded off the air, and for any video files I tried either.  Looking in the frontend logs (/var/log/mythtv/mythfrontend.log) I could see some interesting results when I tried refreshing the metadata for one of the video files:

Apr 23 22:31:46 inception mythfrontend.real: mythfrontend[7669]: 
I MetadataDownload metadatadownload.cpp:280 (runGrabber) Running
Grabber: /usr/share/mythtv -l en -a GB -D 25957
Apr 23 22:31:46 inception mythfrontend.real: mythfrontend[7669]:
I MetadataDownload metadatadownload.cpp:186 (run) Metadata
Lookup Failed: No Results Clear Skies 0 0
Apr 23 22:31:46 inception mythfrontend.real: mythfrontend[7669]: 
I CoreContext videodlg.cpp:3340 (customEvent) No results found for
Clear Skies 0 0

Now the path  /usr/share/mythtv is a valid path on my system, with various things, like the backup tool and such like.  However, it isn't an executable, so consequently, when the system tried to run a directory as an executable, nothing happened.  Finding why this location was being used instead of an actual script took a little bit of digging.

Read more: mythtv meta grabber problems

How I broke ls and rm

Category: Techie
21 May 2013
Written by Andy Hits: 5545

This update is a bit of a question too, so answers on the back of a postcard....

earlier today, I was reviewing the output of a script at work that checks database backups, and warns if the md5sum of the database doesn't differ from the previous days backup. I'd got a warning that it basically hadnt found any new backups from last nights backup which worried me some what.  In the directory holding the md5sums, I ran ls.  Sure enough, a list of md5sums for today, yesterday and historically were listed.  I decided to try and select just todays files

>ls *.today
ls: invalid option -- .
Try `ls --help' for more information.

Strange... all I'm doing is a wild card search.  Changing to its parent directory, running a search worked fine with the wildcard.  Sure enough, results returned.  It was then that I noticed an interesting file name.  rather than showing the name of a database, it was showing as "-.today"

It would appear that somehow ls was interpreting that file name as a parameter to ls, rather than a file, and because it wasn't a valid parameter, it was erroring.  Similar problems happened when trying to remove the file from within its directory, but if specifying a relative or absolute path, rm behaved.

So my question is, why doe linux commands treat filies with a name starting "-." as a paramater?

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