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DRBD on Ubuntu Karmic

Ubuntu 9.10 (aka karmic koala) has a frustrating packaging bug. Even though the stock server kernel includes the DRBD module, the drbd8-utils package depends on drbd8-source. drbd8-source uses DKMS to build the drbd module to match the installed kernel/s. As I stated in the bug report (lp:474660), "really don't like having build-essential installed on production net facing servers, and where possible any productions servers".

As side from personal opinion on whether the module should be bundled or not, the fact is that is bundled and so there is no need for the dependency on drbd8-source. As a work around I have added a meta package to provide drbd8-source, so I don't need to install build-essential and build the module every time a new kernel is installed.

After a quick test it is working well. Here is the


file I used to make it all happen.

Package: dhc-drbd8-source-hack
Version: 0.1
Section: meta
Priority: optional
Architecture: all
Provides: drbd8-source
Maintainer: Dave Hall <[email protected]>
Description: Package to hack around drbd8-source dependency for drbd8-utils

If you are unsure how to use the control file above, see my recent blog post on building meta packages for ubuntu and debian.

Setting up a private package repository is outside the scope of this post. If you want to set one up, I would recommend Sander Marechal's slightly dated howto - Setting up and managing an APT repository with reprepro. With a few changes I found it worked well.

If you have your own repository running you can simply run

sudo apt-get install dhc-drbd8-source-hack drbd8-utils

, if you don't you can run the following commands

sudo dpkg -i /path/to/dhc-drbd8-source-hack*.deb && sudo apt-get install drbd8-utils

. Either way you should now have drbd8-utils installed on ubuntu karmic without having to install the redundant drbd8-source package.

To take it a step further you could build a meta package to install both drbd8 packages and allow you to have a potentially smoother upgrade to lucid. The meta package would contain the following line

Depends: dhc-drbd8-source-hack drbd8-utils

This is similar to what I now have in my HA server meta package.

Linksys will Fix the SRW224G4 Firmware - Eventually

Yesterday I spent about 20 minutes discussing the lack of Firefox/gecko engine browser support in the webgui on the SRW224G4 with someone from Linksys. It was an interesting discussion.

When the SRW224G4 was originally released it supported Firefox but this support was dropped in a later revision which added support for new features and an updated user interface. The plan now is to put the Firefox support back in the next major release of the firmware. If I had a revision 1.0 switch I could downgrade my firmware, but the revision 1.0 firmware which supports Firefox will brick a 1.1 unit.

There were no firm commitments given, but I was told that I should see a Firefox compatible firmware for my SRW224G4 released sometime in the first half of 2008.

During the discussion I found out that the SRW224G4 information on Linksys' Australian website is way out of date compared to the US, the current datasheet makes it clear that the product is only usable with IE. I was told that this would be brought to the attention of the appropriate people, and fixed soon. Hopefully the phone support people will also be told what the real situation is with support for Firefox and other gecko based browsers.

Until I get the new firmware, I have 3 options, use a clunky console app for administering my switch, use IE under WINE or return it and get a refund. I am still deciding what I will do.

I don't think Linksys will be on the top of my list of networking kit vendors for a while. Dropping Firefox support is a serious regression in my book, regardless of the reason for it. I know the tech support guys are the first to cop it from users and the last to be informed about product changes, but the lack information about this issue has been very frustrating. The people responsible for maintaining the various Linksys websites should really lift their game.

If anyone can recommend a good supplier of relatively inexpensive, but reliable SIP desktop handsets, please post a comment.

Linksys Knows the SRW224G4 is Broken and Won't Fix it

Yesterday I emailed Linksys a link to my post about Linksys SRW224G4 switch being unusable with firefox and other FOSS browsers. The only response I received was an auto responder telling me to expect a response within 24 hours. After over 28 hours and another email, I still had no response. I wasn't expecting to get a "it has now been fixed, please test with this beta firmware - [link]", but I did expect something along the lines of "we have received your message and have forwarded it to the relevant section, you should receive a response in the next 5 business days". Instead of waiting any longer, I called Linksys.

After calling I spoke to one of the front line helpdesk people who put me though to Wendell, a Senior Technician at Linksys. I also spoke to Wendell last week about my problems with their WebView webGUI on the SRW224G4.

Wendell again told me that it worked with Internet Explorer 5.5+ and that I may find that some pages wouldn't work properly with firefox. After pushing Wendell, he agreed that it wasn't a case of some pages not working properly, but the unit was unless with any browser other than IE. He also told me that this was an issue which had been known by Linksys for some time, and that currently they have no plans to fix support for browsers other than IE 5.5+. I asked for information about where this was documented, Wendell pointed me to the release notes (a MS Word .doc) for the version 1.2.2a firmware for the SRW224G4/SRW248G4 which is only designed for revision 1.0 hardware - I have a revision 1.1 model, which doesn't have any firmware updates available.

The release notes contained the following information at the bottom of page 1.

8. Web browser availability

The web management interface is best viewed using Internet Explorer 5.5 and up, with a resolution of 1024 x 768. In the current software version, certain pages cannot be viewed well using other browsers. It is recommended to apply the following workarounds.

[then on the next page]

Note: Internet Explorer web browser must be installed prior to running the following procedures.

This is the first time I have ever been told that I should read the release notes for the latest available version of firmware for a device before purchasing it as the release notes may contradict the data sheet for the product.

The datasheet states

Features [...]
  • WebView monitoring allows administrators to view the current status and configuration using their favorite web browser

Under the management heading it states:

Web User Interface Built-in Web UI for easy browser-based configuration (HTTP/HTTPS)

The minimum requirements are pretty clear too:

  • Web-based Configuration Java-enabled Browser
  • Cat5 Ethernet Network Cable
  • TCP/IP Protocol installed on each computer within the network
  • Network Adapter installed in each computer
  • Network Operating System (e.g. Windows®, Linux, MacOS X)

My favourite browser is firefox, and I have java installed (although I see no need for java in the webgui), but I still can't administer my switch.

Instead of sending the unit back to the retailer for a refund, I would much rather see Linksys fix their faulty product.

These days, firefox, and other gecko based browsers, aren't niche browsers, they have a growing market share, not only in Australia, but globally. Large vendors should be supporting open standards and platforms, not just the dominant player.

I would recommend that anyone looking at purchasing any Linksys equipment look for alternatives which are more Free/Open Source Software friendly.

A link to this post will also be sent to Linksys, not just the help desk this time, and I will see what response I get. Keep watching.

Linksys SRW224G4 WebGUI is Broken

Last week I bought a Linksys SRW224G4 switch for my rack. It seemed like a nice piece of kit, and I got it for a good price.

The first part of the setup went well enough, using the telnet interface. As I wanted to get my head around all the options the switch offered, I thought I would try WebView (aka the webgui). The image below shows what I got with Firefox, on Konqueror is worse.

screenshot of broken Linksys SRW224G4 WebGUI

The Linksys helpdesk wasn't very helpful. Most calls weren't returned when promised and the scripts didn't seem to deal with this issue. In the end I was told to use Internet Explorer. I knew it worked with IE6 running under WINE, but that isn't the point. This is a modern piece of network infrastructure - it should work on any browser, especially one which has almost 30% market share in Oceania.

For the last 5 years or so I have used a fair bit of Linksys kit, as I find they build high quality network equipment. Another big plus for Linksys in my book has been their support for FOSS and hacking - especially the WRT54GL and NSLU2. Now I am not so sure.

Instead of just waiting for the ticket to make its way through the internal bureaucracy of Linksys so that eventually a developer investigates the bug, I thought I would lay it all out here for them. So here we go.

The error in the error console is:

Error: tbl.firstChild.firstChild has no properties
Source File: http://192.168.XXX.YYY/js/tabs.js
Line: 24

The code is question is as follows (line 24 is in highlighted:

[...] function setTabset(ths) { [...] var tbl = ths.parentNode.parentNode.parentNode.parentNode; subLinks = document.getElementsByName("lnk"); for (var i = 0; i < subLinks.length; i++) { if (subLinks[i] == ths) { if (subLinks[i].innerHTML == "LogOut") { var msg = "Are you sure you want to Log Off?"; if (!confirm(msg)) { return; } } curTd = tbl.firstChild.firstChild.childNodes[tab].style; [...]

The argument passed to the function above is a HTML element with an id attribute of 'tab_0'. This element exists, it is the "Setup" tab in the screenshot above. Lets walk through the relevant bits of the code.

var tbl = ths.parentNode.parentNode.parentNode.parentNode;

This steps 4 levels up the DOM tree, from the tab_0 element (the whole webgui is rendered using tables). This works fine. Now tbl references a table element with an id of 'Table2'.

Now we skip down to the line which has the error.

curTd = tbl.firstChild.firstChild.childNodes[tab].style;

This attempts to step down 3 levels from the top of the table to one of the tabs and retrieve the style object for that element. Here are the steps

  • tbl - the table itself
  • tbl.firstChild - the first child node of the table - a text node
  • tbl.firstChild.firstChild - a non existent node as the parent is a text node with no children

Why does this work on IE, but not Firefox/Konqueror and other FOSS browsers? I haven't checked for konq, but I know that the gecko engine (used by Firefox, SeaMonkey, IceWeasel etc etc), the DOM parses is whitespace sensitive. Every bit of text (whitespace or otherwise) is considered to be a text node. This is W3C compliant, there is even a bug report for it - see bug #26179 on mozilla's bugzilla.

This is pretty easy to fix, I haven't tested the code below for this case, but something like it usually works.

/* * Find the first child which is a html element */ function findFirstChild(elm) { if ( !elm.childNodes.length ) { return; } var children = elm.childNodes.length; for ( var i = 0; i <= children; ++i ) { if ( elm.childNodes[i].nodeType == 1 ) { return elm.childNodes[i]; } } return; } [...] function setTabset(ths) { [...] curTd = findFirstChild(findFirstChild(tbl)).childNodes[tab].style; [...]

I hope that Linksys sets their QA team on the SRW224G4 firmware with firefox to find the other bugs like this one. Unless Linksys fixes there gecko based browser support rather promptly, I won't be recommending (or using) their products in future.

Special thanks to the Firebug and DOM Inspector extensions which made this so much easier to trace.

Linksys will be emailed a link to this post and my ticket number. I will keep people posted on how things progress.