a user can revert hostapd just using apt-get install
hostapd=2:2.4-1+deb9u4
"apt-cache policy hostapd
hostapd:
Installed: 2:2.4-1+deb9u4
Candidate: 2:2.7+git20190128+0c1e29f-4~bpo9+2
Version table:
2:2.7+git20190128+0c1e29f-4~bpo9+2 500
500 http://debian.mirror.iweb.ca/debian stretch-backports/main
i386 Packages
*** 2:2.4-1+deb9u4 500
500 http://debian.mirror.iweb.ca/debian stretch/main i386 Packages
500 http://security.debian.org stretch/updates/main i386 Packages
100 /var/lib/dpkg/status
"
^ the 2:2.7+git20190128+0c1e29f-4~bpo9+2 release was coming from
stretch-backports
https://wiki.debian.org/LTS
"Debian 9 Stretch i386, amd64, armel, armhf and arm64 (to review before
start) 2020 to June 2022"
