Experiments with sswap(1), srm(1), wipe(1), gdisk(8), lsblk and gpart(8)

On 27/08/2021 12:22, Graham Perrin wrote:

> … sswap(1) to securely delete whatever might be there. …


I took an opportunity to experiment with some of the other utilities 
that were recently installed by security/secure_delete and 
security/wipe. All new to me.

With reference to the attached file, a few points of interest. Some of 
it's PEBKAM, I don't mind sharing my mistakes.

I'll report what might be an obscure bug in lsblk.

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Line 5, misuse of srm – `srm -lv /dev/da0p3` – was followed by peculiar 
output from a run of lsblk. No surprise there.

Lines 131–139, gdisk should have added freebsd-swap at /dev/da0p3, I 
ignored the suggestion to remove the hard disk drive ("Warning: The 
kernel may continue to use old or deleted partitions."), gpart then 
showed nothing (free space) where da0p3 was expected.

Line 152, I used gpart to add freebsd-swap at da0p3.

Lines 288–297, gdisk should have deleted /dev/da0p3, I ignored the 
suggestion to remove the drive, lsblk showed da0p3 still present.

Lines 301–359, tail of /var/log/messages whilst I disconnected then 
reconnected the multi-purpose dock in which the drive was seated.

Line 375, with nothing in the SD card reader at da0, lsblk showed 
freebsd-swap.

Lines 379–383, with the hard disk drive at da4, lsblk showed nothing 
(free space) between da4p2 and da4p4 – the preceding deletion by gdisk 
was a success.

Lines 418–430, gdisk succesfully added freebsd-swap at /dev/da4p3 – the 
partition was detected by lsblk _without_ the need to disconnect then 
reconnect the dock.

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I disconnected then reconnected the dock, lsblk continues to show what I 
might describe as a 'ghost' where truly there's nothing in the SD card 
reader at da0.

da0, where previously there was the hard disk drive on the JMicron USB 
to ATA/ATAPI bridge.