What is a Bogon?
## Definition
A bogon is an IP address that shouldn’t exist on the public internet. In network jargon, it’s a packet or address from a reserved, invalid, or unallocated range—something that has no legitimate business being routed across the open internet. The term emerged from Unix and network administrator culture, where it serves as a useful shorthand for “this is garbage, ignore it.” The etymology is fairly straightforward: “bogon” is a nominalization of “bogus,” meaning something that is fundamentally illegitimate or counterfeit.
Bogons exist in specific ranges defined by RFC (Request for Comments) documentation. These include private IP ranges like 10.0.0.0/8, 172.16.0.0/12, and 192.168.0.0/16 (the addresses your router assigns to your devices), the loopback range 127.0.0.0/8 (which only refers to your own computer), and various reserved or unallocated ranges that haven’t been assigned to any organization yet. When a bogon appears in your network traffic, it’s either a configuration error, a spoofing attempt, or someone who really doesn’t understand how IP addresses work.
## Why It Matters
Bogons matter because they are a fundamental security concept. Filtering bogon traffic is one of the most basic and effective things a network administrator can do to reduce noise and potential threats. If a packet claims to be from 192.168.1.1 but arrives from the internet, that packet is lying. Either it’s a mistake, or it’s malicious. Either way, the correct response is to drop it and move on. Bogon filtering is the network equivalent of not answering a phone call from someone claiming to be your neighbor but using an area code from another continent.
The concept also matters because it represents a fascinating intersection of technical precision and internet culture. The term “bogon” is simultaneously a technical term used in RFCs and router configurations, and a piece of whimsical jargon that sounds like a creature from a fantasy novel. This duality is characteristic of early internet culture, where the people building the network were often the same people who played Dungeons & Dragons and read science fiction. The internet’s technical vocabulary is full of these playful terms: daemon, zombie, cookie, bogon. The people who built the internet had fun while doing it, and the terminology reflects that.
## Example
A network administrator is reviewing firewall logs and notices incoming traffic from 10.0.0.5. The administrator sighs. 10.0.0.5 is a private IP address, which means it should only exist inside a local network, not arriving from the internet. This is a bogon. The administrator checks the source, confirms it’s not from a legitimate VPN tunnel, and adds a filter to drop all bogon traffic. The administrator then drinks their coffee and mutters something about “users” that would make the BOFH proud. The bogon is gone, but the administrator knows it will be back, in some other form, because the internet is a never-ending parade of malformed packets and questionable decisions.
In another scenario, a security researcher is analyzing a DDoS attack. The attacker is using spoofed IP addresses, many of which are bogons. The researcher points out that proper bogon filtering at the ISP level would have prevented much of this traffic from ever reaching the target. The ISP responds that they don’t filter bogons because “it might break something.” The researcher publishes a paper. The ISP gets named in the paper. The ISP eventually implements bogon filtering. The bogon, in its own small way, has changed the internet for the better.
## Internet Angle
The bogon is a perfect example of how internet culture creates its own vocabulary. The term appears in technical documentation, router manuals, and security advisories, but it also shows up in internet humor, memes about network administrators, and lists of “funny technical terms.” The Bogon Reference Pages (maintained by various networking organizations) track bogon ranges and provide tools for filtering them. These pages are simultaneously serious technical resources and monuments to the internet’s love of playful language.
In the broader internet culture, “bogon” has become a metaphor for anything that is fundamentally invalid or fake. A “bogon” in a discussion might be a source that doesn’t exist, a claim that contradicts itself, or a user who is clearly not who they claim to be. The term carries the weight of its technical origins: when you call something a bogon, you’re not just saying it’s wrong; you’re saying it has no legitimate reason to exist in this context. It’s a more precise and more damning accusation than “fake” or “wrong.” It’s a term that says, “This is not just incorrect; this is structurally impossible.”
## Related Terms
– **Bogus:** The parent term from which “bogon” derives. “Bogus” means fake or invalid; a “bogon” is a specific type of bogus IP address.
– **Martian:** A packet that appears to be from Mars—specifically, from a network that doesn’t exist on your routing table. A close cousin to the bogon, though technically distinct. The internet has a talent for naming things after space.
– **IP Address:** The numerical label assigned to each device connected to a computer network. IPv4 addresses are the familiar 32-bit numbers like 192.168.1.1; IPv6 addresses are longer and look like someone fell asleep on the keyboard.
– **RFC (Request for Comments):** The series of documents that define the standards for the internet. RFC 1918 defines private IP ranges; RFC 5735 documents special-use addresses. The internet runs on these documents, and they have the driest, most precise humor you’ll ever find in technical writing.
– **Firewall:** A network security device that monitors and filters incoming and outgoing traffic. The firewall is the bouncer that keeps bogons from entering the club.
– **Spoofing:** The practice of sending packets with false source addresses. A common attack technique that often involves bogon addresses because attackers don’t care about receiving responses.
– **Bogon filtering:** The practice of dropping traffic from known bogon ranges. One of the basic hygiene practices of network administration, like washing your hands but for routers.
– **Unix:** The operating system family that birthed much of modern internet culture, including the term “bogon.” Unix administrators are the spiritual ancestors of today’s sysadmins, and their vocabulary lives on in every router configuration and shell script.