DHCP makes for bad routing. My original problems with DHCP (i.e name resolution) has been solved by nss-mdns, completely replacing my hacky dns server - ssh'ing into hostname.local names work just fine.
But sadly, my WiFi router does not understand mdns hostnames. Setting up a tunnel into my desktop at home, so that I could access it from office (or australia for that matter), becomes nearly impossible with DHCP changing around the IP for the host.
UPnP: Enter UPnP, which has a feature called NAT Traversal. The nat traversal allows for opening up arbitrary ports dynamically, without any authentication whatsoever. Unfortunately, there doesn't seem to be any easily usable client I could use to send UPnP requests. But nothing stops me from brute-hacking a nat b0rker in raw sockets. And for my Linksys, this is how my POST data looks like.
<?xml version="1.0" ?>
<s:Envelope s:encodingStyle="http://schemas.xmlsoap.org/soap/encoding/" xmlns:s=
"http://schemas.xmlsoap.org/soap/envelope/">
<s:Body>
<u:AddPortMapping xmlns:u="urn:schemas-upnp-org:service:WANIPConnection:1">
<NewRemoteHost/>
<NewExternalPort>2200</NewExternalPort>
<NewProtocol>TCP</NewProtocol>
<NewInternalPort>22</NewInternalPort>
<NewInternalClient>192.168.1.2</NewInternalClient>
<NewEnabled>1</NewEnabled>
<NewPortMappingDescription>SSH Tunnel</NewPortMappingDescription>
<NewLeaseDuration>0</NewLeaseDuration>
</u:AddPortMapping>
</s:Body>
</s:Envelope>
And here's the quick script which sends off that request to the router.
--Air is just water with a lot of holes in it.