The icons are mostly from openclipart.org and iconarchive, flaticon.com IIRC.

Going to search them anew, to add proper source references here...

back.png	openclipart / redrawn
clear.png	combined / custom
clipboard.png	http://www.iconarchive.com/show/buuf-icons-by-mattahan/Clipboard-Manager-icon.html
computer.png	https://openclipart.org/detail/5012/laptop
copy.png	???
csv.png	http://www.iconarchive.com/show/windows-8-icons-by-icons8/Files-Csv-icon.html
ethernet.png	https://openclipart.org/detail/174481/network-interface-card-labelled
html.png	http://icongal.com/gallery/icon/2645/128/html_natsu

icon.beta.png icon.cloud.png icon.cmd.png icon.controller.png

icon.copy.png	https://openclipart.org/detail/199334/primary-copy

icon.date.png icon.events.png icon.exchange.png icon.extras.png icon.finduser.png icon.fire.png icon.firewall.png icon.folder.png icon.godzilla.png icon.info.png icon.install.png icon.key.png icon.license.png icon.lnk.png icon.log.png icon.mfcmapi.png

icon.network.png	https://openclipart.org/detail/217136/network-card-from-behind

icon.notes.png icon.office.png icon.powershell.png icon.printer.png icon.registry.png icon.samba.png icon.server.png icon.tools.png icon.unlock.png

icon.users.png	https://openclipart.org/detail/35347/tango-system-users

icon.wmi.png info.extras.png

ping.png	https://openclipart.org/detail/174481/network-interface-card-labelled
sweep.png	https://openclipart.org/detail/182731/sweep
to-user.png	https://openclipart.org/detail/5572/computer-user
user.png	https://openclipart.org/detail/4749/male-user-icon