Matrix defense, how is it supposed to work Options

[Odsh]

In SR5: let's suppose a group of shadowrunners is located in a crowded area, with lots of commlinks and other nodes everywhere around them. Somewhere in the crowd, an enemy hacker starts bricking the team's gear.

Apart from passively resisting the bricking attempts, what can the team's hacker do in response to that kind of attack?
How does he locate the offending persona? Is there anything that makes it stand out in the multitude of icons that surround them?

If that hacker performs the attack from a few km away instead (with some additional noise of course), does his persona appear near the runners (where exactly?), or does it remain at his commlink's location?