Problem Description: The emergence of a soft phone calls using the outside when the Request Timeout after listening port detect errors Wireshark: `Frame Check Sequence:. Bad checksum`, wireshark to see the preference configuration, checksum disable computer networks checksum positioning issues go wrong.
Solution: query using the network command to turn off the checksum function
sysctl -w net.link.ether.inet.apple_hwcksum_tx=0
sysctl -w net.link.ether.inet.apple_hwcksum_rx=0
出错：sysctl: unknown oid 'net.link.ether.inet.apple_hwcksum_tx'
In https://gist.github.com/RichGuk/7252584 find similar key in
Final resolution:
sysctl -w net.link.generic.system.hwcksum_tx=0
sysctl -w net.link.generic.system.hwcksum_rx=0
Note: Execute the command sysctl need to cancel protection system, according to the tutorial http://www.cadhome.com.cn/17646.html processing