ufw-app: add page (#24242)

Co-authored-by: Managor <42655600+Managor@users.noreply.github.com>
Co-authored-by: Ivan Baluta <ivanbaluta.dev@gmail.com>

pages/linux/ufw-app.md

@@ -0,0 +1,29 @@
+# ufw app
+
+> Manage `ufw` application profiles and their associated firewall rules.
+> Application profiles are defined in `/etc/ufw/applications.d/`.
+> More information: <https://manned.org/ufw#head8>.
+
+- List available application profiles:
+
+`sudo ufw app list`
+
+- Display information about a specific or all profiles:
+
+`sudo ufw app info {{profile_name|all}}`
+
+- Allow or deny traffic using a specific profile:
+
+`sudo ufw {{allow|deny}} "{{profile_name}}"`
+
+- Update firewall rules for a modified profile or all profiles:
+
+`sudo ufw app update {{profile_name|all}}`
+
+- Update a profile, adding new rules if none exist:
+
+`sudo ufw app update --add-new "{{profile_name}}"`
+
+- Configure the default behavior of `update --add-new`:
+
+`sudo ufw app default {{allow|deny|reject|skip}}`