Distcc is working.
Howerver, I didn't get it working at the beginning.
Because I am curious about what messages distccd's pass between
themselves. So I fired up wireshark, then I go to sleep.
As you would expect, eventually wireshark occupied all free space on
/tmp which is also used by distcc to produce object files. And as a
consequence, distcc failed.
Originally, the distcc run with "--log-level critical", so it sent
nothing to syslog.
By using this command, you can see what distcc is doing in real time:
distccd --verbose --log-stderr --daemon --user distcc --allow