Running webservers behind dynamic IP addresses

Jani Reinikainen,

23. February 2003

One day my ISP gave me a dynamic IP address (an IP address that changes every time you connect to the Internet). This was not a good solution from my point of view, as I ran a webserver behind this ADSL connection. For this kind of use, a static IP is outstanding, but I really hadn't a choice but to cope, so here are the notes this experiment generated:

Test system 1: Intel Pentium III 450MHz@500MHz (overclocked), 128mb SDRAM, 60gb HD, 10/100mb Intel EtherExpress Pro/100 and RealTek NICs behind a 512kbps/256kbps ADSL line routed over a 4-port Nokia 10mbps ADSL hub/router.
Test system 2: Intel Pentium III 600Mhz@672MHz (overclocked), 256mb SDRAM, 80gb HD, 10/100mb Intel EtherExpress Pro/100 and RealTek NICs behind a 512kbps/512kbps ADSL line routed over a 4-port A-Link RoadRunner 44 10/100mb ADSL switch/router.
First of all, you need to plan every move very carefully. Before you connect the server to the Internet, check it's placement and cable routing. Each time you yank the Ethernet cable your IP address will change, so if you, for example, notice that the server wasn't supposed to be where it's now (you forgot it on your workbench or something similar) and physically need to re-place it, you have no other choice than to grab a new IP. Of course, this is not as big of an issue if you're using WLAN or a similar wireless technology.
Get a DNS host that can be updated via a "client". Updating DNS hosts manually each time your IP changes is a real pain if you have more than one or two domains. I've used both MyDynDns and No-Ip, and both work like a charm. I've also seen a few ZyXEL broad-band routers that have native DynDns support.
If you haven't got an UPS (Uninterrupted Power Supply), be sure not to run all your servers/routers/whatever under the same outlet. Also, placing some of your computer stuff under a completeley different fuse might also add some redundancy.
To get rid of the idle-timeouts (so that I could keep the same IP address for as long as possible) my ISP had, check my crontab tip #2.
If possible, run Heartbeat or some other form of clustered environment. This will increase your uptimes dramatically.