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

From: Graham Perrin <grahamperrin_at_gmail.com>
Date: Fri, 27 Aug 2021 14:59:27 UTC
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.


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 

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.


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.