You can find a list of well known ports used by OS X here.
Ports are a means of separating traffic into different streams according to its purpose: for example the standard port for connecting to a webserver is 80, whilst that used by most SMTP mail servers is 25. Packets being transmitted to, from and within the Internet are addressed to destination IP addresses, where they are intended for a specific network port.
#Icefloor block application outgoing mac
But it will not allow a passing intruder to try to connect to your Mac’s file sharing, as your Mac did not open that connection with the intruder’s system. Thus the firewall will let a remote website send you the contents of a web page when you have already opened a connection with the remote web server. Even when every device on your local network has its own firewall, the malevolent could bombard your network in an attempt to overwhelm it, in a denial of service (DoS) attack.Ī firewall filters network packets, within the modem-router, in a standalone firewall appliance, or in your Mac, according to a set of rules.įor example, a standard default rule blocks all incoming packets originating from the Internet unless they are responses to previously sent outgoing packets. In the absence of a firewall, a potential intruder could identify your modem-router as opening into a local network, and try to send packets to connect to or otherwise disrupt any system on your network. When coupled with an ADSL, cable, 3G/4G or satellite modem, the combination receives packets from the Internet that are addressed to systems on the local network, routing them onto that network, and reverses that process for outgoing packets to the Internet. But it is not just a case of set and forget.Ī network router performs a simple task: it receives incoming packets from one network connection, and routes them to another connection according to the destination address and its configuration. For most, our firewall is the most robust protection between us and the Internet.
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