Prove the 4 GB limit and watch permissions disappear

short · 35 min · Objective 1.3

Task

Format removable media two ways, attempt to copy a file larger than 4 GB to each, and then prove that permissions are discarded when a file crosses onto a file system that cannot record them. Both facts are examinable and both are far more memorable once seen.

Steps

  1. Create a file larger than 4 GB, recording how you made it and its exact size in lab/fs/bigfile.txt.
  2. Format the removable media as FAT32, attempt the copy, and record the result and the exact error text in lab/fs/results.csv with header filesystem,copy_result,error_text,max_file_size.
  3. Reformat as exFAT, repeat the copy, and add the row.
  4. On an NTFS volume, create a folder, remove inherited permissions and grant access to one account only. Record the permission list in lab/fs/perms-before.txt.
  5. Copy that folder to the exFAT media and back to a different NTFS location, and record the permission list at each stage in lab/fs/perms-after.txt. Write lab/fs/why.md explaining, in one paragraph, what happened and why.

Verify

grep -c . lab/fs/bigfile.txt
awk -F, 'NR>1 && NF>=4 {n++} END {print n" filesystem(s) tested"}' lab/fs/results.csv
awk -F, 'NR>1 {print $2}' lab/fs/results.csv | sort -u | wc -l
grep -c . lab/fs/perms-before.txt
grep -Eic 'discard|lost|inherit|no permissions|cannot record' lab/fs/why.md

Two file systems tested with two different copy results, permissions recorded before and after, and an explanation naming what happened to them. If both copies succeeded, the file was under 4 GB.

Notes

This is the fastest route to remembering why a sensitive file on a USB stick has no protection at all. There is nowhere on the medium to record who may read it.

This is an independent study companion for CompTIA A+ Core 2 220-1202 and is not produced by or endorsed by CompTIA.