A MikroTik router with DNS feature enabled can be set as a DNS server for any DNS-compliant client. Visitors observe redirect loop errors when browsing to your domain or observe HTTP.Since this has been elevated to be the canonical question on hairpin NAT, I thought it should probably have an answer that was more generally-valid than the currently-accepted one, which (though excellent) relates specifically to FreeBSD.Description. If no SRV record is found, this technique backs off to a simple DNS host name resolution of the server identifier.The SSL handshake fails between Cloudflare and the origin web server. Instead of performing a simple DNS host name resolution, a CIP client MUST use the technique described in RFC 2052 (DNS SRV) to locate a server with service equal to CIP, protocol equal to TCP, and name equal to the server identifier.Office Tool Plus support multiple edition of Office, Visio and Project, you can configure more options for deploy. Fast & Easy, deploy Office in just two steps. When the remote requests are enabled, the MikroTik router responds to TCP and UDP DNS requests on port 53.Office Tool Plus get Office from Microsoft, make sure you can deploy the latest version of Office.
The server then thinks the client is the gateway itself, and replies directly to it. It has no idea that the two packets are part of the same conversation, so no conversation happens.The solution is that for packets which require such destination NAT, and which reach the gateway from the internal network, to also perform source NAT (SNAT) on the inbound packet, usually by rewriting the source address to be that of the gateway. This may be set to prevent infinite proxy loops or a DoS attack.The client thus sends a packet to an external IP address, but gets a reply from an internal IP address. Since that reply is direct, it doesn't go via the gateway, which therefore never gets a chance to balance the effect of inbound destination NAT on the initial packet by rewriting the source address of the return packet.modproxy , which provides basic proxy capabilities modproxybalancer and one or more. The server then receives a packet with an internal destination address (its own), and an internal source address (the client's) it knows it can reply directly to such an address, so it does so. Step 4: Select the extension you want to remove and then click 'Disable'.The problem arises when the gateway device rewrites the destination address, but not the source address. But to enable hairpin NAT, one would also need a rule such as: iptables -t nat -A POSTROUTING -d 192.168.3.11 -p tcp -dport 80 -j MASQUERADENote that such rules need to be in the right place in the relevant chains in order to work properly, and depending on settings in the filter chain, additional rules may be needed to permit the NATted traffic to flow. Linux uses iptables to do the DNAT thus: iptables -t nat -A PREROUTING -p tcp -dport 80 -j DNAT -to-destination 192.168.3.11Which will enable simple DNAT for the HTTP port, to an internal server on 192.168.3.11. A discussion of which consumer-grade devices are which is off-topic for Server Fault.Proper networking devices can generally be told to work, but - because they are not in the business of second-guessing their admins - they do have to be told do so. Others aren't, and so won't, and it is unlikely that they can be made to work. A diagram may be helpful at this point:Some consumer gateway devices are bright enough to recognise those packets for which the second NAT step is needed, and those will probably work out-of-the-box in a hairpin NAT scenario. The server thinks it's talking to the gateway device. But the solution does exist and is incredibly simple (although not perfect, probably):(1) on the server: add the public IP address as a secondary IP address on the server's network interface with the 255.255.255.255 mask (web service or whatever you want on the server should listen on this IP address too) all modern operating systems will permit you to do this (or a loopback interface with the public IP address assigned to it can be used instead of adding a secondary IP to the primary interface).(2) on the LAN hosts: add a host route for the public IP address, for example, for Windows hosts use the following command: route -p add 203.0.113.130 mask 255.255.255.255 192.168.1.11 (you can also use DHCP "static route" option to distribute the route). Employing two DNS zones is a viable alternative, but not always the solution. It's about accessing a server placed behind NAT from both the Internet and the LAN. So permit me to summarize the solution here.First of all: forget about NAT (if you can) - the question is not at all about configuring NAT. External users, or by configuring the DNS server to respond differently according to the address of the requesting client.Recently answered a similar question: Cisco static NAT not working on LAN side and just realized that this is a Canonical Question. The best is split-horizon DNS, where your organisation serves different answers for the original lookup depending on where the requesting client is, either by having different physical servers for internal vs. Shantae gba modeThis means you don't need hairpin NAT for IPv4 either, because the clients won't be using it.You will still need your existing IPv4 NAT for outgoing connections and port forwarding for incoming connections until most of the world has enabled IPv6 as well.Using IPv6 will give you a better performance than hairpin NAT.With hairpin NAT your client will send a packet through a switch to the router, the router will then perform two rounds of translation and finally send the packet through the switch to the server. And once you have enabled IPv6 and created AAAA records any client supporting RFC 8305 will try IPv6 before IPv4. Create an AAAA record pointing to the IPv6 address of the server.IPv6 has enough addresses to avoid NAT, so you won't need hairpin NAT for IPv6. Keep the existing A record pointing to the external IPv4 of the router. When IPv6 is enabled you need to create an AAAA record for your domain. Mac audio hijack proAnd maybe remind them that the IPv6 protocol has been around for 20 years so they are long overdue in supporting it. These are my suggestions on what to do if the ISP does not currently support IPv6.First tell the ISP that you need IPv6. This translates to better performance.This is true even if you use a switch built into the same box as the router.If you are using an ISP which doesn't support IPv6 I will question whether you should be hosting servers on that network. This means on a roundtrip you reduce the number of passes through the switch from 4 to 2, and you avoid 2 trips through the router and the 4 translations the router would have performed. As a side benefit it gives you some amount of redundancy if one of the connections has an outage.If you cannot find an ISP with IPv6 support you should consider moving your server to a hosting facility. IPv4 and IPv6 are two independent protocols and as such it is no problem at all if those connections go through different routers. On the router connected to the new ISP you can disable IPv4 on the LAN side and then connect the LAN sides of both routers to the same switch. This is for a web server (port 80) and only for IPv4 - the rules for IPv6 and for SSL (port 443) are analogous.# Port forwarding for VM / Container access with „hairpin NAT“.# This was simple port forwarding - access works from outside but not from inside#-A PREROUTING -4 -p tcp -i eth0 -dport 80 -j DNAT -to web.local:80# This is real hairpin NAT which allows „web.local“ to access itself via the VM hosts external IP. This file is in iptables-restore format and can be read into iptables directly (after editing the IP addresses of course). But communication between your LAN and the outside world would first try IPv6 (which wouldn't work), and you would be relying on falling back to IPv4 which at best is a little slower or at worst doesn't happen.Since I also asked this question (see How do I access a network service NATed behind a firewall from inside using its outside IP?) and was redirected here but the answers here didn't provide a solution (in contrast to generic explanations) let my provide my Linux ( iptables specific) solution here to save everybody a few hours of experimentation. If your ISP doesn't support IPv6 but you choose to enable IPv6 on your LAN anyway (maybe using RFC 4193 addresses) and create AAAA records it will work for clients on your LAN reaching the server on your LAN.
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