This certainly isn’t anything new, but more a reminder to check your router’s security settings.
If you haven’t used it before, ShieldsUP! is a site which will scan some or all of the ports on your internet-facing device and tell you if they are visible to the world. Ideally you want everything “stealth”. If it isn’t and you don’t know why, have a look at your router. The port settings will usually be found under “Firewall”, “Packet Filter” or “Security Rules”.
UPnP is often the culprit for “unstealthing” ports. UPnP (Universal Plug and Play) is a protocol which let’s programs manipulate the router so you don’t have to configure it to work with, say, bittorrent. You rarely need to allow inbound traffic though and, even if you do, it should be configured manually. Once you work out what inbound traffic is/isn’t allowed, you should turn UPnP off.