Some years ago I decided to stop using public mail services and decided to buy my own domain and to setup my own mail server at home to handle all of my email. Work was completed very quickly and I got my own working e-mail server and my own mail domain! Some time there was no problems and I was glad to have an opportunity to have full control over my own mail flow.
But little bit later my ISP decided to make my Internet connection cheaper (for them) and they were assigned private IP address to my home Internet connection (192.168.192.2). As you can predict, from that moment my mail server was not reachable from real world and my mail domain was down.
First available solution was to point my MX record to some real mail server in real Internet and to use fetchmail or something like it ti fetch my email to home server. But this solution was not so flexible, and I decided to take one of IP addresses from IP pool of my employer (I am working for hosting company and company owner approved configuration described here) and to assign it to my home server to make my SMTP server available from real world. “It is impossible”, you can say, “You can not set foreign real IP to interface in PRIVATE network of another ISP!”. Yes, it is true, but using some tricks with Linux policy routing an some tunnelling I can do it! This article is about how it has been done by me.
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