Cellular Carriers Inserting SYN, ACK into Network Traffic
 

Has anyone noticed that if you try to port scan (nmap) an IP address (or web URL) from a cellular provider (the grps0 interface in our case) you receive an automatic SYN, ACK back, showing the port as open, even if the port being scanned is actually closed?

Does anyone have any insight into this?

Re: Cellular Carriers Inserting SYN, ACK into Network Traffic
 

Cellular data networks are heavily monitored and tightly controlled by the carriers, I'm not one bit surprised to see them meddling with the traffic...

Re: Cellular Carriers Inserting SYN, ACK into Network Traffic
 

probably your cell provider is "unique"
mine shows closed when i scan my home computer, port 80

Re: Cellular Carriers Inserting SYN, ACK into Network Traffic
 

It might be an attempt to reduce latency on a crappy network.

Re: Cellular Carriers Inserting SYN, ACK into Network Traffic
 

Yes, it's true - actually, it can be NAT-ed too with TCP connection emulation.

It is all for performance.