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 title: Blocking IP Addresses with Caddy
 date: 2026-02-17 16:30:00
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Did you know that there's a Wikipedia page [0] that lists all of
the assigned `/8` IPV4 address blocks?

A person, if they were so inclined, could take this list (or a
subset of it [1]) and block all of those IP addresses from
accessing their website using Caddy's `remote_ip` matcher (or
whatever the equivalent is in your web server of choice).

As an example, let's say that we want to block all of the IP
addresses that are assigned to the United States Department of
Defense for no [2] particular [3] reason [4] whatsoever.

To do that, we can add the following lines to our Caddyfile:

```caddy
@blocked_ips {
    remote_ip 6.0.0.0/8 7.0.0.0/8 11.0.0.0/8 21.0.0.0/8 22.0.0.0/8
26.0.0.0/8 28.0.0.0/8 29.0.0.0/8 30.0.0.0/8 33.0.0.0/8 55.0.0.0/8
214.0.0.0/8 215.0.0.0/8
}

handle @blocked_ips {
    respond 403
}
```

If we want to be really cheeky (as the cartoon dogs my kids are
obsessed with like to say), we could even redirect them to another
website:

```caddy
handle @blocked_ips {
    redir
https://www.archives.gov/founding-docs/constitution-transcript 302
}
```

Before I get emails about how pointless this probably is, I already
know.

It won't prevent someone from accessing your site—or cause anyone
to *care* about your site—if they use a VPN or Tor or their home
network or their smartphone, but for a few lines of config, it's
nothing if not a statement that I'd argue is worth making these
days.

---
[0]: https://en.wikipedia.org/wiki/List_of_assigned_/8_IPv4_address_blocks
[1]: https://en.wikipedia.org/wiki/List_of_assigned_/8_IPv4_address_blocks#List_of_/8_blocks_assigned_to_the_United_States_Department_of_Defense
[2]: https://apnews.com/article/immigration-enforcement-minnesota-4d1499fc5962ab880f3816259e04bdbf
[3]: https://apnews.com/article/minnesota-immigration-enforcement-shooting-crackdown-surge-173e00fa7388054e98c3b5b9417c1e5a
[4]: https://apnews.com/article/immigration-minnesota-boy-father-detained-342f319fafb766d13afe07f5bcc1f112
---


EOF