# Dummy IP & MAC Addresses for Documentation & Sanitization

In this article, we are going to look at a topic that, in my experience, is not well known. There are IP and MAC ranges that are reserved for documentation and can't be routed. There are many use cases for these ranges.

# Use Cases

There are several reasons why you don't want to use real or accessible host addresses. Perhaps the biggest reasons are for **Security & Privacy**: you **want to avoid sharing sensitive information** or **running scripts against 'real' host addresses**.

More examples:
: **Documentation** - in scripts, manuals, articles, ...
: **Placeholder** - in firewall policies, scripts, templates, ...
: **Mock-up** - in product demonstrations, presentations, flyers, ...
: **Sanitize / Anonymize Data** - logs, packet captures, configuration files, ...

There are more, but you know where I am going with this.

**Important**: Just to mention it again, please do not use the following address for anything else to avoid problems.

# IP Addresses

**IPv4** has the following IP address ranges:

`TEST-NET-1` - **192.0.2.0/24** *(192.0.2.0–192.0.2.255)*

`TEST-NET-2` - **198.51.100.0/24** *(198.51.100.0–198.51.100.255)*

`TEST-NET-3` - **203.0.113.0/24** *(203.0.113.0–203.0.113.255)*

Referenced in the [RFC5737](https://datatracker.ietf.org/doc/html/rfc5737#section-3).

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For **Any-Source Multicast** (ASM):

`MCAST-TEST-NET` - **233.252.0.0/24** *(233.252.0.0–233.252.0.255)*

Noted, that it is part of the normal multicast space and referenced in [RFC6676](https://datatracker.ietf.org/doc/html/rfc6676#section-2).

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You have two ranges in **IPv6**:

- **2001:db8::/32**
    - Start: `2001:db8::`
    - End: `2001:db8:ffff:ffff:ffff:ffff:ffff:ffff`
    - Referenced in [RFC3849](https://datatracker.ietf.org/doc/html/rfc3849#section-2)
- **3fff::/20**
    - Start: `3fff::`
    - End: `3fff:fff:ffff:ffff:ffff:ffff:ffff:ffff`
    - Referenced in [RFC9637](https://datatracker.ietf.org/doc/html/rfc9637#section-6)

# Ethernet MAC Addresses

For **Ethernet** you have the following ranges for documentation purposes:

**Unicast EUI-48**:

`00-00-5E-00-53-00` - `00-00-5E-00-53-FF`

**Multicast EUI-48**:

`01-00-5E-90-10-00` - `01-00-5E-90-10-FF`

Both ranges are referenced in [RFC7042](https://datatracker.ietf.org/doc/html/rfc7042#section-2.1.2).

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I have rarely used the **EUI-64** format, so I will just share the [RFC7042](https://datatracker.ietf.org/doc/html/rfc7042#section-2.2.3) reference link rather than plastering half the article with it. 

# Conclusion

I hope you found this article helpful and apply what you have learned at some point.