Mac: Internet blocked over WiFi


I'm not sure how it's happened but for some reason when using a shared internet connection on my iMac (OS X Lion) all internet traffic is now blocked from being sent to my other devices. However things like streaming radio do work.

How can I figure out what's blocking the port used for internet over WiFi?


lo0: flags=8049<UP,LOOPBACK,RUNNING,MULTICAST> mtu 16384
     inet6 fe80::1%lo0 prefixlen 64 scopeid 0x1 
     inet netmask 0xff000000 
     inet6 ::1 prefixlen 128 

gif0: flags=8010<POINTOPOINT,MULTICAST> mtu 1280

stf0: flags=0<> mtu 1280

     ether 00:1e:c2:15:e2:2a 
     media: autoselect
     status: inactive

     ether 00:1e:c2:a3:f7:11 
     inet6 fe80::21e:c2ff:fea3:f711%en1 prefixlen 64 scopeid 0x5 
     inet netmask 0xffffff00 broadcast
     inet netmask 0xffff0000 broadcast
     media: autoselect
     status: active

     lladdr 00:1f:5b:ff:fe:0a:2a:5c 
     media: autoselect <full-duplex>
     status: inactive

       ether 00:1c:42:00:00:08 
       inet netmask 0xffffff00 broadcast
       inet6 fe80::21c:42ff:fe00:8%vnic0 prefixlen 64 scopeid 0x7 
       inet6 ::1 prefixlen 64 
       media: autoselect
       status: active

       ether 00:1c:42:00:00:09 
       inet netmask 0xffffff00 broadcast
       inet6 fe80::21c:42ff:fe00:9%vnic1 prefixlen 64 scopeid 0x8 
       inet6 ::1 prefixlen 64 
       media: autoselect
       status: active

ppp0: flags=8051<UP,POINTOPOINT,RUNNING,MULTICAST> mtu 1500
      inet --> netmask 0xffffff00 

utun0: flags=8051<UP,POINTOPOINT,RUNNING,MULTICAST> mtu 1380
       inet6 fe80::21e:c2ff:fe15:e22a%utun0 prefixlen 64 scopeid 0xa 
       inet6 fd00:6587:52d7:10c5:21e:c2ff:fe15:e22a prefixlen 64
asked on Super User Jan 26, 2012 by EddyR • edited Jan 27, 2012 by studiohack

2 Answers


Check your DNS settings. Most streaming apps use IP-only addresses.

Head to Network prefs, and make sure you're not setup with something custom, like a home router that isn't accessible.

answered on Super User Jan 27, 2012 by RomanT

Your output from ifconfig for en1 shows 2 inet (IP) addresses which is a little confusing and will require more troubleshooting.

The first IP address shown on en1 is which may or may not be right, you would have to check the wireless interface on the computer sharing the connection. I am a little unclear as to whether the iMac is broadcasting its internet connection to share with others or if it's one of the devices that is receiving a shared connection from another.

Either way, unless the sharing system is acting as a DHCP server to hand out IP addresses, chances are you need to configure each device to have an individual IP address.

But then there is this very unusual issue -

en1 also has an IP of which is a result of not getting an IP address from from a DHCP server and is self-assigning a link-local or APIPA address which can not be used when you are trying to access the Internet because the address cannot be routed. (APIPA):

Definition: A feature of Microsoft Windows [and most modern operating systems], APIPA [link-local] is a DHCP failover mechanism for local networks. With APIPA, DHCP clients can obtain IP addresses when DHCP servers are non-functional.
When a DHCP server fails, APIPA allocates IP addresses in the private range to Clients verify their address is unique on the network using ARP. When the DHCP server is again able to service requests, clients update their addresses automatically.

Here is what I recommend to resolve the issue. Hopefully I understood the issue clearly but this is with the understanding that the iMac is the system that is supposed to broadcast the Internet connection and you are connecting other devices to it via WiFi:

Check the configuration of the wireless network interfaces on all devices. If you are using the 10.0.2.x scheme - set the iMac to and the others to through just ensuring that you don't have two devices with the same IP. You will want to set the netmask to on the wireless interface on the iMac as well as all the devices you want to connect - on everything but the iMac, set the default gateway to . Just to be safe, I would manually set the DNS server IP's to and (openDNS) to make sure all your bases are covered.

answered on Super User Jan 27, 2012 by Dustin G.

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