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I came across a tweet complaining about 24 using 2.718.281.828 as an IP address, which obviously wouldn't work. Others responded that using a non-functional IP address is like using 555 for phone numbers.

Is there an equivalent of phone number's 555 (or more specifically, 555-0100 through 555-0199 in the US) used for fictitious IP addresses in tv and movies?

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  • I used "realism" as a tag, but it's more trying to avoid being real. Any suggestions?
    – Andrew Grimm
    Jun 2 '14 at 0:55
  • 3
    Actually, some commands will take ip addresses like that, and simply 'add' them together, so 0.0.0.256 becomes 0.0.1.0. Therefor although it may not work verbatim in all programs, it does point to a real address, namely 4.207.27.60.
    – Shelvacu
    Jun 2 '14 at 7:54
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    The thing about 555 is phone calls are intrusive. Only *4 people are ever going to check an ip address used in a movie by pinging it or whatever, so it doesn't matter if you use a real one. *That's a fact.
    – user9930
    Jun 2 '14 at 12:19
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    Has anyone else noticed that IP is the number e?
    – CDspace
    Jun 2 '14 at 17:43
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    Slightly unrelated but interesting is that example.net, example.org and example.com are reserved by the IANA for documentation purposes: iana.org/domains/reserved
    – Alex KeySmith
    Jun 3 '14 at 13:25
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There was a follow up tweet about this:

The IP address equivalent of 555 phone numbers is actually well documented in RFC5737. e.g. 203.0.113.11 is TV safe. http://tools.ietf.org/html/rfc5737#section-3

Which links to

  1. Documentation Address Blocks

    The blocks 192.0.2.0/24 (TEST-NET-1), 198.51.100.0/24 (TEST-NET-2), and 203.0.113.0/24 (TEST-NET-3) are provided for use in
    documentation.

I don't know what is commonly used in the TV or movie industry, though.

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  • 1
    And we have an RFC for apparently no propose...
    – Braiam
    Jun 2 '14 at 21:08
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    @Braiam providing a safe IP address that is known to be unused for documentation purposes has no purpose? If you want to lord it over the RFCs, it's easier to point to those published on 4/1 as being superfluous and a waste of time.
    – Nick T
    Jun 2 '14 at 22:02
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    Don't forget the my fav website. example.com
    – Reactgular
    Jun 2 '14 at 22:20
  • How about any address starting with 127.?
    – supercat
    Jun 2 '14 at 23:21
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    @Braiam just because it has less purpose than RFC2324 doesn't make it useless.
    – Anthony
    Jun 3 '14 at 3:30
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It is most common to use addresses containing octets outside the possible range of 0 to 255 for a "555-1234"-esque IPv4 analog.

While using valid-looking, "approved" ranges is OK, if an actor need say them aloud they might not be that great. Plus, from the TEST-NET's Andrew mentions, .0.'s aren't cool, and .100. could appear "too ideal". If users are at all familiar with IP addresses (not uncommon nowadays) anything starting with 192.168., the most common block for consumer private networks, could break an audience's suspension of disbelief.

Examples:

  • In 24 Jack gave Chloe an IP address starting with 292
  • Rizzoli and Isles traced an email message back to an IP address like "189.23.290.13"
  • The Net featuring Sandra Bullock
  • Person of Interest chat sessions and more below

Gallery:

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  • That first image is actually from a Person of Interest episode called "Root Cause", that whole show is about a hacker and ex-CIA agent and it's also full of fake IPs.
    – Crow T Robot
    Jun 2 '14 at 21:51
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    Seeing something bigger than 255 seriously breaks suspension of disbelief though.
    – ithisa
    Jun 3 '14 at 2:43
  • "UN*X" is now officially an operating system! (Or maybe they didn't want to use a trademark, just like the rest of us)
    – Andrew Grimm
    Jun 3 '14 at 5:08
  • @AndrewGrimm they probably didn't want to pay SCO licensing fees :P
    – Nick T
    Jun 3 '14 at 5:55
  • Somehow I don't think that "port 42" was an accident...
    – Martin Tournoij
    Jan 25 '16 at 4:02
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Well, you could use ones that are firewall-based, like 192.168.xxx.xxx or 10.1.x.x... those ones are fine because they are internal, and are based on router setups (it'd only connect people to a router on their own network).

Or, assuming we are still talking IPv4 only (I have no idea what you'd do for IPv6 as I'm totally unfamiliar with its format, though it's probably simple math), just break out the rules and use any number beyond 255. Since all IP addresses have to contain 4 numbers less than 2^8 (8 bits of 0 or 1, in case you were wondering what that root is. It's the number of combinations you can get with 8 bits), use something like 300.129.231.56.

I'd guess you probably already know that based on your initial question, so if that's the case, I'd use a firewall-reserved one like 192.168.x.x or 10.1.x.x. There probably are other reserved ones, I just don't know them.

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  • Unfortunately, some programs resolve invalid IP addresses to valid IP addresses as mentioned in the comments of the question.
    – Mooing Duck
    Jun 2 '14 at 16:31
  • You're not wrong, but it's still technically misuse, even if it's not a problem. The TEST-NET IPs mentioned in Andrew Grimm's answer were created for exactly these situations.
    – Matt Nordhoff
    Jun 2 '14 at 19:21
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Adding to the answer by @Andrew: For IPv6 it's 2001:DB8::/32 according to RFC 3849.

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