IPv4 address space has been depleted by far, and more and more countries across the globe are willing to adopt or are already in the process of adopting IPv6 as their following IP protocol.
But as the IPv6 addressing scheme is getting adopted, there have been issues surfacing left, right & center.
Companies willing to go for globally routable IP addresses are being offered IPv6 addresses. However, the fact remains that most of the current publicly available servers are still only reachable through the IPv4 address scheme.
NAT would be required to sustain the Internet during that period, and the NAT would be performed at multiple layers.
ISPs across the globe are deploying large-scale NAT (LSN) systems.
One of such issues that have surfaced is the reputation filtering of email messages.
Most global security systems use a list of IPv4 addresses (public) to identify the spamming servers or hosts globally.
Moreover, the issue would worsen when more and more ISP start deploying LSN systems, only to end up hurting the effectiveness of the IPv4 filtering systems, especially for the security systems that use reputation filtering as their primary email security system.
To better explain this, let us take a scenario. A company’s single public IPV4 address is being NATed to a sizeable IPv6 pool of addresses.
Suppose one of those IPv6 IP addresses is known to send SPAM messages to the entire world. In that case, the honeypots of the global blocklisting servers or the reputation system servers will classify the IPv4 address behind the IPv6 address as a dirty IP.
This will result in blocking that particular IPv4 address and the entire IPv6 address space. This scenario is bleak as more and more security systems across the globe are adopting reputation-based services and doing away with the old content filtering options.
Security systems across the globe are using reputation-based services because this particular technology helps block the SPAM emails before they even enter the network and hence reduces the processing time and cost that are otherwise involved with content filtering solutions.
As the entire world is transitioning toward adopting IPv6 as the new technology for IP addressing, security companies involved in email security will have to continue and enhance their content filtering solutions as the transition from IPv4 to IPv6 will take its toll on reputation-based filtering.
Content filtering solutions seem to be the way ahead in the future, with IPv6 addressing schemes approaching fast.