Operational Status: [Status]
sslip.io is a DNS (Domain Name System) service that, when queried with a hostname with an embedded IP address, returns that IP address. It was inspired by xip.io, which was created by Sam Stephenson.
Here are some examples:
|Hostname / URL||IP Address||Notes|
|https://18.104.22.168.sslip.io||22.214.171.124||dot separators, sslip.io website mirror (IPv4)|
|https://52-0-56-137.sslip.io||126.96.36.199||dash separators, sslip.io website mirror (IPv4)|
|www.192-168-0-1.sslip.io||192.168.0.1||subdomain + dashes|
|https://www-78-46-204-247.sslip.io||188.8.131.52||dash prefix, sslip.io website mirror (IPv4)|
|--1.sslip.io||::1||IPv6 — always use dashes, never dots|
|https://2a01-4f8-c17-b8f--2.sslip.io||2a01:4f8:c17:b8f::2||sslip.io website mirror (IPv6)|
sslip.io can be used to brand your own site (you don’t need to use the sslip.io domain). For example, say you own the domain “example.com”, and you want your subdomain, “xip.example.com” to have xip.io-style features. To accomplish this, set the following three DNS servers as NS records for the subdomain “xip.example.com”
184.108.40.206or whatever name server you're currently using. The sslip.io name servers are not public recursive name servers. They will not resolve regular domain names (e.g. "google.com").
Let’s test it from the command line using
dig @ns-gce.sslip.io. 169-254-169-254.xip.example.com +short
Yields, hopefully: [connection timed out]
If you want to run your own DNS server, it's simple: you can compile from source or you can use one of our pre-built binaries. In the following example, we install & run our server within a docker container:
docker run -it --rm fedora curl -L https://github.com/cunnie/sslip.io/releases/download/2.6.1/sslip.io-dns-server-linux-amd64 -o dns-server chmod +x dns-server ./dns-server 2> dns-server.log & dnf install -y bind-utils dig @localhost 127-0-0-1.sslip.io +short # returns "127.0.0.1"
You can acquire TLS certificates for your externally-accessible hosts from certificate authorities (CAs) such as Let's Encrypt. The easiest mechanism to acquire a certificate would be to use the HTTP-01 challenge. It requires, at a minimum, a web server running on your machine. The Caddy web server is one of the most popular examples. For example, if you had a webserver with the IP address 220.127.116.11, you could obtain a TLS certificate for "18.104.22.168.sslip.io", or "www.22.214.171.124.sslip.io", or "prod.www-52-0-56-137.sslip.io".
If you have procured a wildcard certificate for your branded / white label / custom sslip.io-style subdomain, you may install it on your machines for TLS-verified connections.
When using a TLS wildcard certificate in conjunction with your branded sslip.io style subdomain, you must use dashes not dots as separators. For example, if you have the TLS certificate for *.xip.example.com, you could browse to https://www-52-0-56-137.xip.example.com/ but not https://www.126.96.36.199.xip.example.com/.
if you're interested in acquiring a wildcard certificate for your sslip.io domain, e.g. "*.52-0-56-137.sslip.io", the procedure is described here.
Experimental features can change; don't depend on them.
You can use sslip.io's DNS servers (
ns.sslip.io) to determine your public IP address by querying
TXT record of
dig @ns.sslip.io txt ip.sslip.io +short # sample reply "2607:fb90:464:ae1e:ed60:29c:884c:4b52" dig @ns.sslip.io txt ip.sslip.io +short -4 # forces IPv4 lookup; sample reply "188.8.131.52" dig @ns.sslip.io txt ip.sslip.io +short -6 # forces IPv6 lookup; sample reply "2607:fb90:464:ae1e:ed60:29c:884c:4b52"
This feature was inspired by Google's DNS lookup, i.e.
dig txt o-o.myaddr.l.google.com @184.108.40.206
+short. There are also popular HTTP-based services for determining your public IP address:
A big advantage of using DNS queries instead of HTTP queries is bandwidth: querying
ns-aws.sslip.io requires a mere 592 bytes spread over 2 packets; Querying https://icanhazip.com/ requires 8692 bytes spread out over 34 packets—over 14 times
as much! Admittedly bandwidth usage is a bigger concern for the one hosting the service than the one using the
dig @ns-gce.nono.io version.status.sslip.io txt +short "2.6.0" "2022/07/14-18:25:29-0700" "6512ebd"
The first number, ("2.6.0"), is the version of the sslip.io DNS software, and is most relevant. The other two numbers are the date compiled and the most recent git hash, but those values can differ across servers due to the manner in which the software is deployed.
dig @ns-aws.sslip.io metrics.status.sslip.io txt +short "Uptime: 82059" "KV Store: etcd" "Blocklist: 2022-07-15 16:40:03-07 2,3" "Queries: 6399908 (78.0/s)" "Answered Queries: 2202200 (26.8/s)" "A: 1974882" "AAAA: 87362" "TXT Source: 269" "TXT Version: 8" "TXT KV GET/PUT/DEL: 21/7/7" "PTR IPv4/IPv6: 0/0" "NS DNS-01: 455" "Blocked: 66"
127-0-0-1.sslip.io.), the second, IPv6 PTR queries
[Status] A status of “build failing” rarely means the system is failing. It’s more often an indication that when the servers were last checked (currently every six hours), the CI (continuous integration) server had difficulty reaching one of the three sslip.io name servers. That’s normal. [connection timed out]
DNS runs over UDP which has no guaranteed delivery, and it’s not uncommon for the packets to get lost in transmission. DNS clients are programmed to seamlessly query a different server when that happens. That’s why DNS, by fiat, requires at least two name servers (for redundancy). From IETF (Internet Engineering Task Force) RFC (Request for Comment) 1034:
A given zone will be available from several name servers to insure its availability in spite of host or communication link failure. By administrative fiat, we require every zone to be available on at least two servers, and many zones have more redundancy than that.