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Re: Follow-up to yesterday's BerkeleyLUG meetup



Aaron:

Thanks. Good information.

-- Chris Peeples --
(c) +1-510-851-0968
🇺🇦 "Russian warship, go f**k yourself"
"I don't need a ride, I need ammunition"





On Monday, August 28, 2023 at 08:32:26 AM PDT, ace36 <acohen36@gmail.com> wrote:


Following yesterday's in-person meetup, would like to point out at least these three items:

1. Ran into the identical meet.jit.si issue Rick M pointed out in http://linuxmafia.com/pipermail/sf-lug/2023q3/015885.html
Quoting a snippet from Rick's SF-LUG mailing-list post:
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
A change:  Initial _creation_ (opening) of a room on public Jitsi Meet
demonstration instance "meet.jit.si" now requires login authentication
using a Google Account _or_ a Facebook account _or_ a GitHub account.
I've just verified this.  Authentication is _not_ required for joining a
room once it's been opened.
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

As this particular "Auntie Google" a.k.a. "mz googly" account am currently using is apparently not quite as portable as some of its advocates might otherwise adamantly claim, went ahead and created an ad hoc (but very portable!) GitHub account to initially create/open yesterday's https://meet.jit.si/BerkeleyLUG instance. Seems that was the only person present online here from ~12Noon until sometime before 2:00pm :-\

2. Chris P mentioned using MS Windows' 'chkdsk' to scan hard disk drives "C:\" , "D:\" , "E:\" , ...etc.
I went ahead and pointed out that Linux has a similar commandline utility for scanning hard disk drives called 'badblocks'.
Quoting from both 'man 8 badblocks' at the Linux commandline as well as https://www.man7.org/linux/man-pages/man8/badblocks.8.html  .......
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
NAME
       badblocks - search a device for bad blocks
SYNOPSIS
       badblocks [ -svwnfBX ] [ -b block_size ] [ -c blocks_at_once ] [
       -d read_delay_factor ] [ -e max_bad_blocks ] [ -i input_file ] [
       -o output_file ] [ -p num_passes ] [ -t test_pattern ] device [
       last_block ] [ first_block ]
DESCRIPTION
       badblocks is used to search for bad blocks on a device (usually a
       disk partition).  device is the special file corresponding to the
       device (e.g /dev/hdc1).  last_block is the last block to be
       checked; if it is not specified, the last block on the device is
       used as a default.  first_block is an optional parameter
       specifying the starting block number for the test, which allows
       the testing to start in the middle of the disk.  If it is not
       specified the first block on the disk is used as a default.
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

Typically, you would use '# badblocks -svvn /dev/sdX' as the superuser from a liveDVD/liveUSB distro's command prompt where X is the entire hard drive you're badblocks-checking (e.g., the command arguments' /dev/sda, /dev/sdb, /dev/sdc, /dev/sdd,...etc.) and decidedly _W/O_ any hard drive partitions mounted at all (e.g., sda1, sda2, sda3,sda4, sda5, sda6, ...sdXn...etc.)

Reason for this last point briefly explained further on in the badblocks(8) manpage:
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
-f     Normally, badblocks will refuse to do a read/write or a
              non-destructive test on a device which is mounted, since
              either can cause the system to potentially crash and/or
              damage the file system even if it is mounted read-only.
              This can be overridden using the -f flag, but should
              almost never be used --- if you think you're smarter than
              the badblocks program, you almost certainly aren't.  The
              only time when this option might be safe to use is if the
              /etc/mtab file is incorrect, and the device really isn't
              mounted.
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

Recommended command options explained:
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
-s     Show the progress of the scan by writing out rough
              percentage completion of the current badblocks pass over
              the disk.  Note that badblocks may do multiple test passes
              over the disk, in particular if the -p or -w option is
              requested by the user.
-v     Verbose mode.  Will write the number of read errors, write
              errors and data- corruptions to stderr.
-n     Use non-destructive read-write mode.  By default only a
              non-destructive read-only test is done.  This option must
              not be combined with the -w option, as they are mutually
              exclusive.
-w     Use write-mode test. With this option, badblocks scans for
              bad blocks by writing some patterns (0xaa, 0x55, 0xff,
              0x00) on every block of the device, reading every block
              and comparing the contents.  This option may not be
              combined with the -n option, as they are mutually
              exclusive.
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
             
Warning to be carefully heeded:
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~  
WARNING !!!
       Never use the -w option on a device containing an existing file
       system.  This option erases data!  If you want to do write-mode
       testing on an existing file system, use the -n option instead.
       It is slower, but it will preserve your data.
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

Lastly, a '# badblocks -svvw /dev/sdX' (specifically using the -w write-mode option here) performed on that 1 TB (1000 GB) spinning-platter, non-SSD drive could take -- and actually _has_ taken -- half-a-week or longer running non-stop to complete! :-O


3. Was unable to reach any websites through wireless access using native Debian 12.1 bookworm installed on a Dell Latitude notebook I brought along to Caffe Strada yesterday, but _was_ able to use a Linux Mint liveUSB to boot and successfully access websites through Caffe Strada's WAP (wireless access point).
Perhaps obvious to others -- although not so obvious to me at the time -- it so far appears that Debian's ConnMan network frontend https://packages.debian.org/bookworm/connman and https://wiki.debian.org/WiFi/HowToUse#ConnMan was/is somehow unable to effectively DNS-resolve IP addresses on the Latitude.
At least these options present themselves...
- effectively "fix"/re-configure ConnMan , systemd's 'connmanctl', and/or its underlying DNS resolver to re-enable DNS using the appropriate SSID WAP entries
- replace ConnMan with IWD/IWCtl  as per https://wiki.debian.org/WiFi/HowToUse#IWCtl and using systemd's 'systemctl'
- completely gut the Debian 12.1 bookworm installation on the Dell Latitude and replace it with a fresh installation of something like Linux Mint (as above with the liveUSB) or Bodhi Linux 7.0 , either of which IMHO are likely to more effectively DNS-resolve IP addresses from the start


-A


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