Networking
What is ASN?
An ASN identifies a network that controls its own routing policy and announces its address space to the global routing table via BGP. A provider running its own ASN controls its routing, peering and address space directly rather than reselling someone else's.
Why ASN matters
A provider running its own ASN controls its routing, peering and address space directly rather than reselling someone else's. OnionVPS operates AS200558.
ASN in practice
When you run a server on a network with its own ASN, the ASN is what your peers see when you announce routes. You would look at BGP sessions and prefix announcements, and you would change them only if you had direct control of peering—which most single-server users do not. Get it wrong—announce a prefix you do not hold, or leak a route—and the wider internet can blackhole your traffic or hijack your neighbours' prefixes.
What people get wrong about ASN
The common error is thinking your ASN is assigned to your individual server, like an IP address. It is not. The ASN belongs to the network operator—the autonomous system—not to one host. Your server does not have an ASN; the network it lives on does. Correct it: your ASN is the one attached to the provider's routing domain, not something you configure per machine.
ASN — common questions
Can I get my own ASN for my VPS?
Not for a single server. An ASN is for a network that runs its own BGP routing. Running your own ASN requires announcing your own prefixes and peer agreements, which one VPS cannot justify. You can buy an ASN and request provider-independent IP space, but you would still need a BGP-capable setup and a provider willing to announce your prefix.
Does my VPS have an ASN?
Your VPS does not have an ASN; the network it is on does. Your provider, OnionVPS, operates AS200558. That ASN is what your traffic appears to originate from and what others use to identify your network in BGP routing decisions. Individual servers are identified by IP addresses, not ASNs.
More from networking
- BGP
- BGP is the protocol that autonomous systems use to exchange routing information and decide how traffic crosses the internet.
- IXP
- An IXP is a shared physical facility where networks interconnect directly rather than paying a transit provider to carry traffic between them.
- Peering
- Peering is a direct interconnection between two networks that exchange traffic with each other without paying a third party to carry it.
- IP transit
- Transit is a paid service in which one network carries another network's traffic to the rest of the internet.
- Anycast
- Anycast announces the same IP address from several locations at once, so each user is routed to the nearest instance by BGP.
- IPv6
- IPv6 is the current version of the Internet Protocol, using 128-bit addresses to replace the exhausted 32-bit IPv4 space.
- Reverse DNS
- Reverse DNS maps an IP address back to a hostname through a PTR record, the inverse of a normal DNS lookup.
- Port 25
- Port 25 is the TCP port used for server-to-server SMTP mail delivery.