Fake HTTP Get Requests

Question

i have noticed certain sites which allows limited hit per IP so can i programatically make them feel that requests are not coming from the same IP ,

well i am not

Answer 1

I am guessing the filter is being applied at the IP packet level rather than at the higher level HTTP level. In this case Yes and No.

Yes - it is technically possible to spoof your IP address so the IP packets look like they've come from elsewhere.

No - in that it is unlikely to be useful. If you spoof the "from" address on the TCP packets, then any replies from the machine you are connecting to will be lost as they try to route to the spoofed IP address. You'll get nothing back.

That is, you won't even be able to complete the TCP Three-Way-Handshake. Until that process is completed, you cannot even send anything down the connection - because there isn't even a connection, to begin with. HTTP runs over TCP, so unless you complete the handshake (which requires a valid 'from' IP address), you can't make any use of this.

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An old trick was to use something called "Source Routing"; where TCP packets included information on how to route the information. This was for diagnostic use way back "in the day". You could put yourself in the designated route, and then just stop the packets when they reach you and reply to them, again with the source-routing information.

But this technique does not work at all anymore, because almost every single router on the Internet these days simply drops source-routed packets, as there is no legitimate need for them - and lots of potential havoc to be wreaked.