You'll know when it happens. Unless you make a pastime of pissing off people on the Internet, it's not something you need to worry about at home. It's much more common for people who host sites/content/servers for other people because then the host feels the wrath of whoever the customers have pissed off.
In this case I suspect one of the people I host Soldat or other servers has someone who doesn't like them.
I only noticed these attacks because one of my servers had a bit of packet loss (and I have more than just hosting which goes through that server), so I flipped to a terminal tab where I track the interface usage of my servers. if there's a strange volume of network traffic there, then I use tcpdump to figure out what it is and block accordingly.