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I work at an enterprise with enterprise-type software on my machine regarding firewalls, virus scanning, and vpns. I'm also a developer.

If I'm not connected to the internet I'm not able to debug my application. I can run it, and connect to it locally. But if I specifically try to debug with IntelliJ it just hangs before it executes any code.

I'm unsure of the cause, but I'm wondering if it's possible to block debuggers when not internet connections are available via firewall? Maybe a stupid question but I always thought firewalls only effected outgoing connections.

  • Do you know the applications code ? Because for me it sounds like the app executes some anti debugger trick (why ever only with internet access) – SleepProgger Oct 15 '15 at 18:21
  • You mean, do I have the source code? If so yes. Also, I've tried monitoring network traffic and I don't see any outbound connections. Also, if it was because of the application it shouldn't work when i try to run normally instead of debugging. If that wasn't your question, then I misunderstood :-) – Carlos Bribiescas Oct 15 '15 at 18:25
  • @Sleep + Carlos: this appears to be about debugging Java. Java doesn't have access to raw memory, CPU instructions, or system calls commonly used for anti-debugger (mostly by malware). Anyway, Java doesn't use the inter-process-by-OS controls used to debug native, but rather a TCP connection from the debugger to an "agent" within the target JVM (but outside the user's code). This is always a TCP connection even on the same host, so network could be involved, although IME firewalls usually don't bother localhost connections. – dave_thompson_085 Oct 20 '15 at 9:26
  • Is IntelliJ not giving you any error message? Ever after a delay? I use Eclipse which after at most a minute gives a popup about "failed to connect to remote VM". If you're on Windows, you could get and run TCPView from www.sysinternals.net (now actually part of MS, but their old name is more convenient than navigating MS website) and look for connections being attempted but failing. – dave_thompson_085 Oct 20 '15 at 9:32

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