First of all, you probably have a crappy home router like the rest of us. By default it does routing, NAT and DHCP in one. NAT is very important because your ISP will only give you one ip address at a time. Try any host in your LAN and browse to Your Ip Address
. You will notice they all return the same one and it will not start with '192.168.' NAT translates the one ip to multiple ips on the other side (and vice versa.) There are ip addresses that fall in to the realm of private addresses. Click here to read up
. The '192.168.*.*' addresses I mentioned fall into this realm. They are also know as unroutable ips. You need no routing on LANS, however so they are perfect for home routers with NAT. So how does an outside host access your inside private ip host? The simple answer is port forwarding and your router "should" support it. Look at your manual. Basically config your router to forward all packets that come on the public address to the internal address of your choice (i.e. 18.104.22.168:21 forwards to 192.168.1.78:21) The connection is transparent to the remote host.