Squid access from outside machine: how did it happen?

I've got Squid (2.2S5) running on a small LAN, so the only machines
that should be accessing it have IP addresses of 192.168.0.*. Yet
today, while perusing the access.log, I saw this:

944671200.372 28 210.228.110.51 TCP_DENIED/403 1024 GET http://damedabe.virtualave.net/env2.cgi - NONE/- -

How did this machine (210.228.110.51 == p031.shingu.cypress.ne.jp) get
access (even if denied) to Squid?

Thank you.

*** Steve Snyder ***
Received on Fri Dec 10 1999 - 07:37:46 MST