Category Archives: Linux

General Linux and Open Source related blog posts

Getting your old Sync Server to work with New Firefox

Much has been written about Mozilla trying to force people to use their new sync service.  If, like me, you run your own sync server for Firefox, you’ve mostly been ignoring this because there’s still no real way of running your own sync server for the new service (and if you simply keep upgrading, Firefox keeps working with your old server).

However, recently I had cause to want to connect my old sync server to a new installation of firefox without just copying over all the config files (one of the config settings broke google docs and I couldn’t figure out which one it was, so I figured I’d just blow the entire config away and restore from sync).  Long ago Mozilla disabled the ability to connect newer Firefoxes to an old sync server, so this is an exposé of how to do it.  I did actually search the internet for this one, but no-one else seems to have figured it out (or if they have, they’re not known to the search engines).

There are two config files you need to update get new Firefox to connect to sync (note, I did this with Firefox 37; I’ve not tested it with a different version, but I’m pretty sure it will work).  The first is that you need to put your sync key and weave user login into logins.json.  Since the password and user are encypted in this file, the easiest way is to use a password manager extension, like Saved Password Editor add on.  Then you need two new password entries of type “Annotated” under the host chrome://weave.  For each, your username is your weave username.  For the first, you’re going to add your weave password under the annotation “Mozilla Services Password”.  For the second, add the Firefox  key with all the dashes removed as the password under the annotation “Mozilla Services Encryption Passphrase”.  If you’ve got all this right, password manager will show this (my username is jejb):

tmpNext you’re going to close firefox and manually edit the prefs.js file.  To sync completely from scratch, this just needs three entries, so firstly strip out every preference that begins ‘services.sync.’ and then add three new lines

user_pref("services.sync.account", "<my account>");
user_pref("services.sync.serverURL", "<my weave URL>");
user_pref("services.sync.username", "<my weave user name>");

For most people, the account and weave user name are the same.  Now start Firefox and it should just sync on its own.  To check that you got this right, go to the Sync tab of preferences and you should see something like this


And that’s it.  You’re all done.

Squirrelmail and imaps

Somewhere along the way squirrelmail stopped working with my dovecot imap server, which runs only on the secure port (imaps).  I only ever use webmail as a last resort, so the problem may be left over from years ago.  The problem is that I’m getting a connect failure but an error code of zero and no error message.  This is what it actually shows

Error connecting to IMAP server "localhost:993".Server error: (0)

Which is very helpful.  Everything else works with imaps on this system, so why not squirrelmail?

The answer, it seems, is buried deep inside php.  Long ago, when php first started using openssl, it pretty much did no peer verification.  Nowadays it does.  I know I ran into this a long time ago, so the self signed certificate my version of dovecot is using is present in the /etc/ssl/certs directory where php looks for authoritative certificates.  Digging into the sources of squirrelmail, it turns out this php statement (with the variables substituted) is the failing one

$imap_stream = @fsockopen('tls://localhost', 993, $errno, $errstr, 15);

It’s failing because $imap_stream is empty, but, as squirrelmail claims, it’s actually failing with a zero error code.  After several hours of casting about with the fairly useless php documentation, it turns out that php has an interactive mode where it will actually give you all the errors.  executing this

echo 'fsockopen("tls://localhost",993,$errno,$errmsg,15);'|php -a

Finally tells me what’s wrong

Interactive mode enabled

PHP Warning: fsockopen(): Peer certificate CN=`' did not match expected CN=`localhost' in php shell code on line 1
PHP Warning: fsockopen(): Failed to enable crypto in php shell code on line 1
PHP Warning: fsockopen(): unable to connect to tls://localhost:993 (Unknown error) in php shell code on line 1

So that’s it: php has tightened up the certificate verification not only to validate the certificate itself, but also to check that the CN matches the requested service.  In this case, because I’m connecting over the loopback device (localhost) instead of the internet to the DNS name, that CN check has failed and lead to the results I’m seeing.  Simply fixing squirrelmail to connect to imaps over the fully qualified hostname instead of localhost gets everything working again.

Getting a Windows Printer (Ricoh Aficio SP 204) natively running on Linux

Printing and scanning has always been the bane of Linux.  I thought I solved it three years ago by getting a nice network printer (HP OfficeJet Pro 8600) which spoke postscript and could scan to folder (provided you have samba installed).  Unfortunately, this is an inkjet printer and about three months ago the initial cartridges (which are deliberately lightly loaded) ran out of ink.  Purchasing new ones (it’s colour so I need four) turned out to be an arm and a leg (or 2x what the printer cost to buy in the first place).  Three months after replacement, the whole thing died with a call HP technicians error.  This turns out mostly to mean my ink cartridges are leaking.  Sure enough the entire inside is awash with a substance more costly than liquid gold … plus it’s now all over my shirt and trousers.  Trying to clean it out just gets ink all over the desk and some important papers.  Of course, since it’s a UK purchased printer and I’m now living in the US, HP support “cannot help”.  Vowing never to purchase another @!**#@ inkjet printer as long as I live, it’s time to find a cheap multi-function laser (did I mention the scanner function on the HP won’t work either now because when it gets this error it locks every function).

Investigating lasers, the cheapest multi-function seems to be a Ricoh Aficio SP204 N (the N means netowrk connected, which is nice) for US$60, which is a bargain, plus it’s a laser.  Google confirms it can scan to pdf (via file share or email), the only drawback is that the printer engine is “windows only” (one of those direct render on the system and send to printer ones).  Further googling around for the printer and linux drivers (and even DDST, the Ricoh name for their direct rendering protocol on linux) yields nothing.  Looks like I’ll be writing a driver when it arrives.  Fortunately, there is a way of running it (using KVM instead of VirtualBox) providing you have a windows virtual machine, so that’s the initial plan.  The only other annoyance is it doesn’t do duplex (either for scanning or printing).  Bummer, but you can’t have everything for US$60.

When the printer arrives, it turns out it has a web interface (yay) but you can’t program scan destinations with it (and without scan destinations, it won’t scan) … bummer.  Install the windows virtual machine with the Ricoh driver and use the tool to program scan to email; amazingly enough it all works correctly (it even scans in colour).  Followed the redirection directions with ghostview, ghostscript and redmon and successfully attach the printer to Linux.

Now to get the thing working under linux.  First step is to use tcpdump to track the communication between the windows machine and the printer:

tcpdump -n -w /tmp/ -i eth0 <printer ip>

And then print something.  Looking at the trace file in wireshark, the windows driver uses the HP Jetdirect port (9100).  In wireshark, select the first packet to this port and right click on “follow TCP stream”.  That gives the whole file the windows system sent.  Now save it to a file (tmp.winprint) and see if that’s enough the get the printer going.  You do this by sending the saved file to the printer with netcat:

nc <printer ip> 9100 < tmp.winprint

Wonder of wonders, it prints the same page again, so now we have the correct format to send.  A quick view with emacs reveals a HP PJL (Print Job Language) encoded header and footer with binary data in between.  This is the header:

@PJL SET TIMESTAMP=2014/07/22 18:31:06 

And this is the footer:


So it all seems relatively straightforwards: each page is rendered as a pixel map in the jbig compressed image format (it’s lossless, like gif) and the header describes exactly the size and dimensions of the image.  So getting it working seems to be very straightforward: just generate the jbig images and slap on the header and footer.  Ghostscript doesn’t render natively to jbig, but it will render to ppm and the jbigkit renders what I need.  The image dimensions can be obtained from the ppm with the ImageMagick identify command.  The only fly in the ointment is the DOTCOUNT.  This shows per page how many black pixels are printed and must be something to do with the way the printer tracks the cartridge use; however, it can be faked for the moment.

The jbig format is also used in faxes, so I asked google if anyone else had a piece of code that does the split.  Since it would have the “@PJL SET COMPRESS=JBIG” line, I did a code search for that;  what do you know, it turns up a linux driver for the Ricoh Aficio SP 100:

To add insult to injury, the READMEs mention terms I’ve been searching for for ages (like Ricoh and DDST) and the driver filter even has them in the file name … honestly, for being allegedly the primary search engine of the internet, you’d sometimes wonder if google could find its own arse with both hands.

So, download this and install it and, yay, it works.  Looks like the only real difference between the SP 100 and the SP 204 is that the latter has a higher resolution mode (1200×600) and also can be adjusted to use a bypass tray (which is set in the header too).

I’ve done an initial package here and will be updating for the SP 204 additional features.