<%
''Get the visitor's address
ip=Request.ServerVariables(REMOTE_ADDR)
''The allowed IP address range is 10.0.0.0~10.68.63.255
allowip1=10.0.0.0
allowip2=10.68.10.71
response.writecheckip(ip,allowip1,allowip2)
functioncheckip(ip,allowip1,allowip2)
dimcheck(4)
checkip=false
ipstr=split(ip,.)
allow1=split(allowip1,.)
allow2=split(allowip2,.)
ifcint(allow1(0))>cint(allow2(0))then'' determines whether the IP address segment is legal
response.writeForbidden access
exit function
endif
fori=0toubound(ipstr)
ifcint(allow1(i))<cint(allow2(i))then
ifcint(allow1(i))=cint(ipstr(i))then
check(i)=true
checkip=true
exitfor
else
ifcint(ipstr(i))<cint(allow2(i))then
check(i)=true
checkip=true
exitfor
else
ifcint(ipstr(i))>cint(allow2(i))then
check(i)=false
checkip=false
exitfor
else
check(i)=true
checkip=true
endif
endif
endif
else
ifcint(allow1(i))>cint(ipstr(i))orcint(allow1(i))<cint(ipstr(i))then
check(i)=false
checkip=false
ifi<>ubound(ipstr)then
exitfor
endif
else
check(i)=true
endif
endif
next
if(check(0)=trueandcheck(1)=trueandcheck(2)=trueandcheck(3)=false)and(cint(allow2(2))>cint(ipstr(2)))then
checkip=true
endif
endfunction
%>
Excerpted from WebShell's Blog