# on-line kernel debugging using USB to DB9



## vikasmn (Apr 5, 2010)

Hi Everyone,

I just started working on FreeBSD and I have a couple of questions:
1). Is On-line kernel debugging possible using USB to DB9 adapter or should I use only COM1 port (I dont have one)?
2). I want to see the internel working of in-kernel NAT (IPFIREWALL_NAT) on FreeBSD. What is the best way to do this or to do Symbolic debugging on freeBSD?...Can on-line Kernel debugging help me in this?

Please help me out on this.

This is my first post and looking forward to hearing from you guys. Thanks.


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## trasz@ (Apr 6, 2010)

1. I believe it is possible to use USB dongle to debug the kernel.  I didn't try it yet, though.

2. Remote GDB might help you there (http://www.freebsd.org/doc/en/books/developers-handbook/kerneldebug-online-gdb.html); however, you will need two machines.  Also, if you want to see how things work (as opposed to debugging a crash), you could try to use DTrace.


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## vikasmn (Apr 12, 2010)

Thanks so much...I am now trying to use Dtrace for my analysis...


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