Glossary

IPv6

IPv6 is the current version of the Internet Protocol, with addresses of 128 bits written as eight groups of four hexadecimal digits.

IPv6 is the current version of the Internet Protocol, with addresses of 128 bits written as eight groups of four hexadecimal digits. IPv4 addresses are 32 bits, and the increase in width is the change that motivated everything else.

#What is different in practice

The header is a fixed length, options moved into extension headers, and address allocations are large enough that a single customer commonly holds a whole block rather than one address. That last point is the one that matters for proxy work.

#Why filtering works differently

Because a single subscriber may hold an enormous block, blocking one IPv6 address achieves nothing: the next request can come from a neighbour in the same allocation at no cost. Targets that filter IPv6 therefore act on a prefix rather than an address. Which prefix length any given site uses is not published, and there is no reason to expect two sites to agree, so treat any specific figure you read as a guess unless it comes with evidence.

Privacy addressing complicates it further. Hosts generate temporary addresses that change over time, so an IPv6 address is a weaker long-term identifier than an IPv4 address, while the prefix is a stronger one.

#Availability for scraping

Many targets remain reachable only over IPv4, and many proxy products are IPv4 only. Whether the endpoint you bought can carry IPv6 at all, and whether the destination publishes an AAAA record, are two separate questions and both are testable in a few seconds.

dig AAAA example.com +short
curl -6 -sI https://example.com/ | head -1

With a proxy in the path, the address family used to reach the proxy and the family used from the exit node onward are independent. Test the second by asking a service what address it observed.

#Commonly confused with

Dual-stack means both protocols are available, not that both are used for a given connection; the client picks. A proxy reachable over IPv6 is not necessarily able to reach IPv6 destinations, and the reverse also happens. See CIDR and subnet for the prefix arithmetic.

Frequently asked questions

Are IPv6 proxies harder or easier to block than IPv4?

Individual addresses are trivially replaced, so blocking one is pointless and targets act on prefixes instead. Whether that makes your traffic easier or harder to stop depends on how large a block sits behind your exits and how much of it you share with other customers.

Why do so few proxy providers offer IPv6?

Demand follows targets, and a large share of scraping targets still answer only on IPv4, so IPv6 exits cannot reach them. Support also has to exist end to end, from the gateway to the exit to the destination, and a gap anywhere makes the feature useless.

How do I check which protocol my proxied request actually used?

Ask a service to report the address it observed and look at the format of the answer. Note that the family you use to reach the proxy is independent of the family the proxy uses onward, so a request made over IPv6 can still arrive at the destination over IPv4.