That probably is about the only reason you would use the former construct, these days. The reason you’re seeing this is probably that the default of ipv6only changed in nginx 1.3.4. Prior to that, it defaulted to off; in newer versions it defaults to on. This happens to interact with the IPV6_V6ONLY socket option on … Read more
It’s very bad. Here is a list of examples of what I have first hand experience with consumer ISPs doing to fight the shortage of IPv4 addresses: Repeatedly shuffling around IPv4 blocks between cities causing brief outages and connection resets for customers. Shortening DHCP lease times from days to minutes. Allow users to choose if … Read more
The MAC address might be unique, but there’s nothing special about the number that would indicate where it is. MAC 00-00-00-00-00-00 might be on the other side of the planet from 00-00-00-00-00-01. IP is an arbitrary numbering scheme imposed in a hierarchical fashion on a group of computers to logically distinguish them as a group … Read more
IP subnets exist to allow routers to choose appropriate destinations for packets. You can use IP subnets to break up larger networks for logical reasons (firewalling, etc), or physical need (smaller broadcast domains, etc). Simply put, though, IP routers use your IP subnets to make routing decisions. Understand how those decisions work, and you can … Read more
You’ve already got a working answer but just in case you are curious what was wrong with your original approach, the answer is that you need parentheses around your alternation otherwise the (\.|$) is only required if the number is less than 200.
As we all know that IPv4 address for localhost is 127.0.0.1 (loopback address). Actually, any IPv4 address in 127.0.0.0/8 is a loopback address. In IPv6, the direct analog of the loopback range is ::1/128. So ::1 (long form 0:0:0:0:0:0:0:1) is the one and only IPv6 loopback address. While the hostname localhost will normally resolve to 127.0.0.1 or ::1, I have seen cases where someone has bound it to an IP … Read more
Try to ping another device from your local network (pinging localhost or a website is not the same). Try to ping from target_ip to source_ip (opposite direction). If you have response in any of 2 cases above, check the firewall on your target machine (or as in your case, for Windows, make sure you are … Read more
While there are IPv6 equivalents for the IPv4 address range, you can’t convert all IPv6 addresses to IPv4 – there are more IPv6 addresses than there are IPv4 addresses. The only sane way around this issue is to update your application to be able to understand and store IPv6 addresses.