<blockquote>
Fail2Ban is an intrusion prevention software framework that protects computer servers from brute-force attacks.
</blockquote>
Source: <a href="https://en.wikipedia.org/wiki/Fail2ban" class="autolinkedURL autolinkedURL-url" target="_blank">en.wikipedia.org/wiki/Fail2ban</a>
Fail2ban detects repeated failed logins, and bans the IP address. Subsequent attempt to establish SSH connection from this IP will be blocked. It is available as package in most Linux distro repositories. It works out of the box without configuration. I highly recommend installing it in all Linux servers.
<h1 id="common-usage">Common Usage</h1>
Unban an IP address
<pre><code class="lang-bash">sudo fail2ban-client set sshd unbanip 123.123.123.123
</code></pre>
List jail names
<pre><code class="lang-bash">sudo fail2ban-client status
</code></pre>
List blacklisted IP addresses for SSHD
<pre><code class="lang-ssh">sudo fail2ban-client status sshd
</code></pre>

> Fail2Ban is an intrusion prevention software framework that protects computer servers from brute-force attacks.

*Source: https://en.wikipedia.org/wiki/Fail2ban*

Fail2ban detects repeated failed logins, and bans the IP address. Subsequent attempt to establish SSH connection from this IP will be blocked. It is available as package in most Linux distro repositories. It works out of the box without configuration. I highly recommend installing it in all Linux servers.

# Common Usage

Unban an IP address

```bash
sudo fail2ban-client set sshd unbanip 123.123.123.123
```

List jail names

```bash
sudo fail2ban-client status
```

List blacklisted IP addresses for SSHD

```ssh
sudo fail2ban-client status sshd
```




Unban IP In Fail2ban

The blog is older than you know. I prefer counting from the emergence of one integral anomaly to the emergence of the next, in which case this is the forth version.
