In fail2ban 0.10.0 and later, the following command will remove an IP address from all fail2ban jails as well as from the fail2ban database:

$ sudo fail2ban-client unban <IP-ADDRESS>

The old syntax, which required to specify a jail, can still be used to remove an IP from a specific jail:

$ sudo fail2ban-client set <JAIL-NAME> unbanip <IP-ADDRESS>

To view all active jails:

$ sudo fail2ban-client status

To view all IPs in a jail (most recent entries are at the end):

$ sudo fail2ban-client status <JAIL-NAME>

Documentation: manpages.debian.org/unstable/fail2ban/fail2ban-client.1.en

Disabling manual uploading of themes and plugins can be used as an extra layer of security in WordPress. The implementation in Apache 2.4 is simple:

<LocationMatch "^/wp-admin/update.php">
  <If "%{QUERY_STRING} =~ /.*action=upload-(plugin|theme).*/">
    Require all denied
  </If>
</LocationMatch>

Exceptions for trusted IP addresses can be made by adding extra requirements to the block:

<LocationMatch "^/wp-admin/update.php">
  <If "%{QUERY_STRING} =~ /.*action=upload-(plugin|theme).*/">
    Require all denied
    Require ip 192.0.2.1
    Require ip 192.0.2.2
  </If>
</LocationMatch>

Documentation: Apache HTTP Server version 2.4 – Documentation – Access Control

Changelog

• 2020-10-23. Added link to the official documentation for the Require directive.

PHP versions in Linux distributions commonly used in web servers:

According to the CSS Selectors specification, a group of selectors is invalid if any of the individual selectors it contains is invalid. Then the whole CSS rule with the invalid selector becomes invalid and is not applied at all.

Example case

This is a CSS rule with one declaration and a group of two selectors:

li:hover ul,
li:focus-within ul {
    background-color: yellow;
}

In browsers that don’t recognize both selectors, the whole group of selectors and, as a result, the whole rule become invalid.

For instance, Internet Explorer 11 and—as of 26 January 2020—Microsoft Edge do not understand :focus-within. So, they invalidate the whole group and, as a result, li:hover ul has no effect either, even though it is a selector perfectly understood by both browsers.

A solution

A solution is to avoid grouping and just make a separate rule for the unsupported selector. In this solution, the above example becomes:

li:hover ul {
    background-color: yellow;
}

li:focus-within ul {
    background-color: yellow;
}

Now browsers that don’t support :focus-within will not apply the style for li:focus-within ul, but at least they will apply the style for the universally supported li:hover ul.

Documentation and references

• W3C – Selectors Level 3 – Groups of selectors
• MDN web docs – CSS – Combinators and selector lists
• Microsoft Edge Development – Issue #16651302

Table is current as of 8 August 2020, WordPress 5.5. See populate_roles().