My question is how i can accelerate the scanner?

I'd start by leaving out the concatenation of empty strings, which you are doing no less than three times in the code. I wonder why you do this.

Futhermore, the bottleneck in this code is most likely to be the network - and more specific, the latency. The most obvious way is to do all this in parallel. You might want to use fork() or a select() loop. Or threads if you want to be buzzword compliant.

Abigail