bind sockets to random IP addresses from specified prefixes
npm install freebindinspired by freebind (the C project), this library takes advantage of the IP_FREEBIND socket option on Linux and allows you to bind sockets to random IP addresses from specified prefixes.
freebind.js is only supported on Linux -- it won't work on other platforms (since they don't have a FREEBIND socket option).
note that it is still very experimental, potential bug reports and pull requests are welcome.
2a00:1450:4001:81b::/64 to your server. In order to make use of freebinding, you first need to configure the Linux AnyIP kernel feature in order to be able to bind a socket to an arbitrary IP address from this subnet as follows:
> ip -6 route add local 2a00:1450:4001:81b::/64 dev lo
> usage
freebind supports creating TCP sockets, and also provides a dispatcher wrapper for use with (aka native node >=18 fetch)$3
`js
import { randomDispatcher } from 'freebind'const dispatcher = randomDispatcher('fc00:dead:beef::/48')
const example1 = async () => console.log(
await fetch(
'https://icanhazip.com',
{ dispatcher }
).then(a => a.text())
)
// connections on IPs may be held open
// unless you explicitly close the connection
await example1(); // ~> fc00:dead:beef:4465:f5e0:26d4:2921:6891
await example1(); // ~> fc00:dead:beef:4465:f5e0:26d4:2921:6891
await example1(); // ~> fc00:dead:beef:4465:f5e0:26d4:2921:6891
await example1(); // ~> fc00:dead:beef:4465:f5e0:26d4:2921:6891
const example2 = async () => console.log(
await fetch(
'https://icanhazip.com',
{ dispatcher,
headers: { connection: 'close' }
}
).then(a => a.text())
)
await example2(); // ~> fc00:dead:beef:7d1e:b71e:1c77:1cc6:8a07
await example2(); // ~> fc00:dead:beef:31cd:a6e7:be0b:6872:b51a
await example2(); // ~> fc00:dead:beef:8f8e:c97f:2ba2:3a6:9d7b
await example2(); // ~> fc00:dead:beef:3a48:bb50:d193:471c:f553
/** If a hostname has no IPv6 (AAAA) record while you are trying to access
** it via IPv6 (or vice versa for IPv4 - although that would be pretty rare),
** freebind.js will throw an exception. This can be overridden by using { strict: false },
** which will make it fall back to regular fetch with IPv4. This is not the default
because in many cases, this is not what you really want. /
const dispatcher2 = randomDispatcher('fc00:dead:beef::/48')
const example3 = async () => console.log(
await fetch(
'https://ipinfo.io/json',
{ dispatcher,
headers: { connection: 'close' }
}
).then(a => a.text())
) // ~> Uncaught 'family mismatch for addr 34.117.59.81'
const dispatcher3 = randomDispatcher('fc00:dead:beef::/48', { strict: false })
const example4 = async () => console.log(
await fetch(
'https://ipinfo.io/json',
{ dispatcher,
headers: { connection: 'close' }
}
).then(a => a.text())
) // ~> {"ip":"127.0.0.1", "city": ...
`$3
js
import { tcp } from 'freebind'// a random address will be bound to this socket
const sock = await tcp.createRandomSocket('::1', 9999, 'fc00:dead:beef::/48')
// returns a net.Socket: https://nodejs.org/api/net.html#class-netsocket
// you can also specify a specific address
const sock2 = await tcp.createSocket('hostname.com.example', 9999, 'fc00:dead:beef::b00b')
// you can also specify how many bits to
// randomize (the remainder is zeroed out)
const sock3 = await tcp.createRandomSocket('::1', 9999, 'fc00:dead:beef::/48', undefined, 8)
// (starting from most significant bits, e.g.
// the could be bound to IPs like:
// fc00:dead:beef:2c00::, fc00:dead:beef:3b00::
// fc00:dead:beef:f500::, and so on
``