What is the GPRINT output plugin for?

[Vladimir Nikishkin <lockywolf@gmail.com>]

Dear Netfilter users,

I have been recently trying to find out how to efficiently log
suspicious packets passing through my firewall. While perusing ulogd2
examples, as well as netfilter mailing list, I found about the existence
of the GPRINT output plugin.

However, the basic stack suggested in ulogd.conf:
```
stack=log4:NFLOG,gp1:GPRINT
```
did not really work for me, ulogd was complaining about
```
ulogd.c:854 type mismatch between GPRINT and NFLOG in stack
```
And the log file was empty.

I haven't found any other documentation for GPRINT.
What is it and what is it for?

-- 
Your sincerely,
Vladimir Nikishkin (MiEr, lockywolf)
(Laptop)