Is external_acl_type must under authentication mode?

[NetSnake <netsnakecn@xxxxxxxxx>]

hi,all
I want to use external_acl_type to distribute my user to different
server, these user need NOT authentication.
Squid start my application, but when I access to a special host, no
data send to my program from Squid.
my program is a very simple script, and when I use an existing
application such as ip_user_check, still no actions.
My squid configuration is:
external_acl_type checkip concurrency=0 ttl=0 children=1 %SRC
/usr/local/squid/libexec/
checkip.pl
http_port 80 accel vhost vport
cache_peer www.myhost.com parent 80 0 no-query no-digest originserver name=host1
acl ipaddress external checkip
cache_peer_access  www deny ipaddress
...

My program is very simple:
cat checkip.pl
#!/usr/bin/perl
$| = 1;
open(LOG, ">/tmp/squid.log");
print LOG "RUNNING\n";
close(LOG);
while(defined($line = <STDIN>)){
    print "OK\n";
    open(LOG, ">>/tmp/squid.log");
    print LOG "Got: $line\n";
    close(LOG);
}


So, I think that, is external_acl_type must under authentication mode?

thanks in advance.