Installing Canon LBP2900 Printer on Ubuntu 20.04

The instructions for installing Canon LBP2900 Printer on Ubuntu 20.04 remain pretty much the same as given in an earlier post about Installing Canon LBP2900 Printer on Ubuntu 16.04. The few differences seen this time around are the following:

1) Newer version of LINUX-CAPT-DRV-v271-UKEN: Download link as mentioned on the Canon Support page.

The tar ball includes 64-bit installers: cndrvcups-common_3.21-1_amd64.deb & cndrvcups-capt_2.71-1_amd64.deb (also includes rpm files & 32-bit versions).

2) Depdency on libglade2-0: 

$ sudo apt-get install libglade2-0

3) Workaround for CAPT 64-bit OS issues linking to 32-bit libraries: 

As mentioned in the earlier post, there are certain dependencies for CAPT running in 64-bit OS in linking to 32-bit libraries. Even though, the two deb files (mentioned above) get installed without the dependencies, peculiar behaviour/ error message is seen when the dependecies are missing. On the final step to View Status of printer on captstatusui, an error message is shown: "Check the DevicePath of /etc/ccpd.conf". 

The solution to the problem is to simply check the missing dependencies:
(Check for error messages such as not executable, not found, etc.)

$ ldd /usr/bin/captfilter

$ ldd /usr/bin/capt* | sort | uniq | grep "not found"

In case of error install the missing dependencies:

$ sudo apt-get install libc6:i386 libpopt0:i386

$ sudo apt-get install zlib1g:i386 libxml2:i386 libstdc++6:i386

4) Follow the remaining instructions of the earlier post:

=> Install CAPT printer driver (downloaded .deb files mentioned above)

=> Add printer to the system: (Command line lpadmin or system-config-printer or UI System Settings > Printers):
 
=> Add printer to ccpadmin

=> View status of printer on captstatusui (should show "Ready to Print" if installed correctly)

=> Finally, print test page to finish!

 

Secure DNS

Domain Name System (DNS) is one of the backbones of the internet. DNS helps translate a URL (e.g. blahblah.com) to its corresponding IP address (i.e. 10.02.93.54). Thanks to the DNS human's can access the internet via human friendly URL, than having to remember & punch in numeric IP. So much simpler to say "look it up on Google", than saying "look it up on 172.168...".

Working of DNS

The working of the DNS involves looking up DNS servers spread out over the internet. When a user enters a URL in the browser, the address resolver in their system looks up the DNS servers configured at their system (router/ network, ISP, etc.) for the corresponding IP address. The resolver recursively looks up the Root DNS server, then the top level domain (.com, .in), then second level domain (Google, Yahoo, etc.) (the Authoritative server for the domain), & from it finally the sub-domain (www, mail, etc.) to arrive at the corresponding IP address.

DNS requests are typically made in plain text via UDP or TCP. In addition to destination URL, these requests also carry enough source identifiable information with them. Together with the recursive nature of the lookups via several intermediaries, this makes DNS requests vulnerable to being observed & tracked. The response could even be spoofed via a malicious intermediary that changes the IP address & direct the user to a scam site.

DNS over HTTPS (DoH)

A very recent development has been the introduction of DNS over HTTPS (DoH) in Firefox. HTTPS is the standard protocol used for end-to-end encryption of traffic over the internet. This prevents eavesdropping of the traffic between the client & the server by any intermediary.

To further secure the DNS request, DoH also brings in the concept of Trusted Recursive Resolvers (TRR). The TRR is trusted & of repute, & provides guarantees of privacy & security to the user. The default for Firefox is Cloudflare, though other TRRs are available for the user to choose from. Sadly though, OpenDNS isn't onboard with DoH or TRR, instead has its own offerings called DNSCrypt. Hope to see more convergence as adoption of these technologies improves in the future.

Setting-up DoH with Firefox (ver. 65.0) requires going to Preferences > Network Setting & checking "Enable DNS over HTTPS", with the default Cloudflare TRR. Alternatively, the flags "network.trr.mode" & "network.trr.uri" could be set-up via the about:config.

To confirm if the set-up is correct, navigate to the Cloudflare test my browser page & validate. This should result in successful check marks in green against "Secure DNS" & "TLS 1.3". Some further set-ups may be needed in case the other two checks fail.

For DNSSEC a DNSSEC compatible DNS server will need to be added. Pick Cloudflare DNS, Google DNS or any other from the DNS severs list. On the other hand, for Encrypted SNI indicator, the flag "network.security.esni.enabled" can be enabled. Since ESNI is still at an experimental stage, there could be changes (or bugs) that get uncovered & resolved in the future.

Enabling at a Global Level

The DoH setting discussed here is limited to Firefox. DNS lookups done outside of Firefox from any other browser, application or OS is unable to leverage DoH. DoH at the global/ OS level could be set-up via proxies. Given that DoH is over HTTPS, primarily a high level protocol for secure transfer of Hyper Text Documents, it maybe preferable securing DNS directly over TLS protocol.

In this regard DNS over TLS (DoT) is being developed. Ubuntu ver.18.0 & some Linux flavours offer DoT support experimentally. While DoT has some catching up to do viz-a-vis DoH, raging debates are continuing regarding the merits & demerits of the two options for securing DNS requests. Over time we can hope for the gaps & issues to be resolved, & far better privacy & security offered to the end-user.

Update 1 (25-Feb-21) 

Reference links regarding enabling DoH across devices.

Enabling In Android:
- https://android.stackexchange.com/questions/214574/how-do-i-enable-dns-over-https-on-firefox-for-android 

(In addition to the various network.trr.* settings to use OpenDns Family Shield DoH, additionally lookup the IP for the domain name "doh.familyshield.opendns.com" & set that value to network.trr.uri) 
- https://blog.cloudflare.com/enable-private-dns-with-1-1-1-1-on-android-9-pie/

DoH Providers:
- https://github.com/curl/curl/wiki/DNS-over-HTTPS (Cloudflare also offers a Family shield/ filter)
- https://support.opendns.com/hc/en-us/articles/360038086532-Using-DNS-over-HTTPS-DoH-with-OpenDNS
- https://support.mozilla.org/en-US/kb/dns-over-https-doh-faqs

Ubuntu 16.04 32-bit Display Issue/ Corruption on load/ boot

Recently tried refurbishing an old Benq Joybook U102 laptop with an Ubuntu OS. This one has a 32-bit Intel Atom Processor with 1G Ram, so needed the 32-bit Ubuntu-16.04 iso image (from alternative downloads).

Followed this up with the standard routine of creating a bootable usb using the downloaded iso, booting with the usb, plugging in the Lan cable (wifi drivers are initially unavailable/ downloaded later), formatting the disk & doing a fresh install (choosing the option to download all third-party drivers, etc). All this went off smoothly & the laptop was ready to reboot.

After restarting however found the display corrupted. Practically the entire screen from the left to right was covered with bright coloured stripes, dots & squares rendering it unusable. After a bit of fiddling around found a work-around to close the lid & reopen it, forcing the laptop to go into standby & then exit by pressing the power button. This did help restore the display, but felt there had to be a better solution.

A few suggestions online were to downgrade the Ubuntu kernel to an older version 4.12 or lower. Further search revealed the actual Bug in Kernel 4.13 : Intel Mobile Graphics 945 shows 80 % black screen. The work-around solution of Suspend/ Resume, as well as the proper solution of setting GRUB_GFXPAYLOAD_LINUX=text in grub file are mentioned there.

Setting the variable GFXPAYLOAD to text makes Linux boot up in normal text mode, typically to avoid display problems in the early boot sequence. As instructed made the addition to the /etc/default/grub file, ran sudo update-grub, rebooted, & the display issue was gone!

Installing Canon LBP2900 Printer on Ubuntu 16.04

Capturing notes on installation of Canon LBP2900 printer on a 64-bit Ubuntu 16.04 (a first for this version) locally (usb). These are essentially a mix and match of instructions from the pages Canon CAPT Driver, installing canon printer on debian systems, & Canon CAPT driver in a sequence that works.

=> Pre-requisites:

 

- Cups installation:

(Note: These instructions are from the alternate open source foo2capt library library. I have retained the installs for now, did not apt-remove. Not sure if all of them are actually needed.

As such, the foo2capt code failed to build & install with a whole lot of other missing/ invalid dependency issues. The foo2capt project rewrite seems to be on, so for now dropped the idea of experimenting with it any further.)

- Work around to known CAPT 64-bit OS issues linking to 32-bit libraries:

=> Download & install the Linux CAPT printer driver:

Download Linux_CAPT_PrinterDriver_V260_uk_EN.tar.gz, also linked here.

- Untar & install the 64-bit > Debian packages: 

=> Add printer to system:

- Start/ Restart cups service:

 

 - Can be done via the command line using lpadmin:

  

- Alternatively can be done via System Settings > Printer:

Either type on terminal: 

Or via System Tools > System Settings & Search for Printer

At this point a new printer gets created in my system with the name "Canon-LBP2900-CAPT-English".

(NOTE: Important to use the port 59787 (and not 59687). Also note that in the /etc/ccpd.conf, port 59787 is mentioned as UI_Port (& used by the captstatusui to communicate), while port 59687 as PDATA_Port files. Once ccpd services have been started, you can telnet to check that these ports are listening. )

 

=>  Add printer to ccpadmin:

- Add "Canon-LBP2900-CAPT-English" to ccpadmin: (will override any existing/ old entry)

- Now there should be a proper entry corresponding to the printer "Canon-LBP2900-CAPT-English":

=> Restart ccpd services:

The ccpd services need to be restarted since they don't start up automatically, there could also be the one ccpd process issue.

 

=> View status of printer on captstatusui:

- In case you see a communication error, unplug your printer & plug it in again. On my system this works & the printer status changes to:
 "Ready to Print"

(Note: Steps for setting up capt rules for usb add/remove could also be tried out.)

=> Print test page:

 Next print a test page on "Canon-LBP2900-CAPT-English" & that's it for the set-up. 

 

Update Apt Repositories Location for Old Ubuntu Versions

When working with an old versions of Ubuntu (11.04, 10.04, etc.), the biggest handicap is the lack of a functional package manager such as apt or synaptic. The reason why the package managers stop working is that at end of support/ licence for an old version of Ubuntu, the team behind Ubuntu archive the repositories.

At this point as an user you are supposed to Upgrade (the recommended practice) to a more recent version. There are normally enough advance notices and alerts sent out by Ubuntu's Update Manager for the same. If however, you have a compelling reason to stick on to your current version, then here's a   way to update your repositories' sources list to be able to install and use old software that is present in the archival repository. This is based on the recommendation made on this forum discussion.