FTB cannot connect to the internet.

[FunnnnyDrake]

When I start up the FTB launcher, the console shows the message "java.net.SocketException: Permission denied: connect". Any thoughts?

 

[Ashzification]

Firewall, antivirus, or too much internet traffic

 

[999Destroyer]

You need to do 2 things:

1) Run this from the Windows command prompt (Run As Administrator) as a workaround to disable stateful FTP filtering so that Windows Firewall will not block FTP traffic.

netsh advfirewall set global StatefulFtp disable

(see http://stackoverflow.com/questions/10473518/workaround-for-apache-ant-install-bug/10473581#10473581)

2) Add _JAVA_OPTIONS and _JPI_VM_OPTIONS to your system (!) environment variables and set both to:
-Djava.net.preferIPv4Stack=true

This worked for me.