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Thx for your time, appreciated.


  • I am customer of a ISP (
  • My PC is connected with my ISP's Modem to the internet.
  • The ip-addresses my ISP provides are non-static

I want to switch ip-address and i know how to do (it involves among other to disconnect the modem.) I want to know if switching ip-address is a "router" or "pc" thing. I want to automate the switching without involving unplugging cables,... I would be able to switch OS if necessary, or if you recommend (atm i have Win7)

Could the "right" router automate the switching OR are there even some created for that purpose?

I want to automate my website testing with different ip-addresses and i need to know if i could programm under a certain environment (OS, Router,..) a software to do the switching in a matter of seconds.

I already use Selenium and Watir but want to go a step further.

share|improve this question
Why do you need to switch IP addresses? The only scenarios I can think of are spamming or cheating some online voting/promotion/moderation system that limits IP. – Sep 5 '11 at 1:03
wow. instead of taking time to write a stupid and offending post try better to read my post carefully – Email Sep 5 '11 at 2:00
does your workstation get a real IP from the isp via dhcp, or is the "modem" actually a router, that is providing NAT? – gview Sep 5 '11 at 5:14
up vote 1 down vote accepted

IP allocation on your ISP's side can vary depending on ISP. It is something that is typically handled by edge/core routers at the ISP and can be MAC based or circuit based. It can change depending on lease length or whether the ISP manually allocates a new address or not. Sometimes switching MAC addresses will help, but in some cases it requires a flush of the ARP cache by the ISP. Sometimes it does not matter what you plug in, you always get the same IP, but that will change after a week or so (as it is based on the MAC address of your modem). Sometimes the circuit itself is allocated an IP and no matter what you plug in, your ISP will change it based on their needs.

In any case, there is usually nothing you can do in most cases to consistently change it in a matter of seconds. There are so many reasons why ISPs will not allow this. The only possibility is to be able spoof the MAC of whatever registers with the core routers at the ISP if that ISP happens to do it solely based on MAC address used and doesn't require ARP flushes. If this is the case you would need to script the router or the modem to change its MAC based on specified criteria (which not all routers or modems can even do).

EDIT: I should also mention that MAC address spoofing to continually obtain new IPs may be against your ISP's terms of service, check on that first.

share|improve this answer
hi; yes i am interested in ... ["If this is the case you would need to script the router or the modem to change its MAC based on specified criteria (which not all routers or modems can even do)."] There has to be a solution since i am sure i am not the first nor only one searching for this. using proxis is no option for me. you seem to be experienced, ty for your answer – Email Sep 4 '11 at 23:55
Scripting the router depends on your router model, if it is a web interface (most-likely scenario) you would have to use something like AutoIt or some other automation software to make the change (but could probably also automate your website testing as well). If it has a console interface or can be accessed by SSH/Telnet, then you have many more options (perl, python, etc). – MaQleod Sep 5 '11 at 20:58

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