Scary Stuff in My Router Log

[#1]

I have my router (Netgear DG834G) set up to email me logs every few days.  But recently I've been seeing some worrying things in the form of a  "NETGEAR *Security Alert* [b2:ec:c5]"  One email from this morning contains this:
UDP Packet - Source:82.39.72.122,6146 Destination:87.XXXXXXXX - [DOS]
TCP Packet - Source:68.53.159.141,3870 Destination:87.XXXXXXX - [DOS]
UDP Packet - Source:24.222.6.190,10070 Destination:87.XXXXXXX - [DOS]
The 87. "i think" is my IP address? so I didnt include it in the message.  One from last night had about 20 of these.
What is this?  Does it mean someone is trying to access my PC...should I be worried?  It has only recently started, I havent seen it before in the nearly 7 years i've had the router.

[#2]

I believe it is an indication that your Netgear firewall is successfully doing its job of blocking attempted DOS attacks (I get short bursts of them from time to time and then none for weeks on end...........)

[#3]

I'd only be concerned if these start to appear on a regular basis, they do seem to be from different origins with the first IP being on Virgin Media's network.

[#4]

You can get that if you have used a p2p program recently and its turned off, anyone that has had a connection to your pc will have your IP saved until its flushed over time.  So you will get repeated attempts for its attempts to handshake looking for a connection.
But anyway have a look in your routers security settings for "Block Ping from Internet" or similar and enable it., as by those logs if you are not a p2p user then it could be someone is using infected pc's trying to find an insecure router/pc/webserver to infect.  If they can't See your router they can't.

[#5]

Quote from: _Adam_Walker_

I'd only be concerned if these start to appear on a regular basis, they do seem to be from different origins with the first IP being on Virgin Media's network.

They do appear regularly    Several dozen since December.   I had 5 email logs from the router yesterday, with about 100 of those in total.
I've never used p2p, you mean fileshareing?

[#6]

Yes file sharing, but you can be using it and not know it.  Some games when patching offload the bandwidth on to your connection, steam uses it for near enough all its games if you don't turn it off.  Plus a recent update to flash player has added a new p2p option, no idea where it is used but its there for a reason.