NAt doesn't working

["Antropov Anton" <anton.antropov@kamatel.ru>]

Hi there!

I am trying to set up NAT using IPTABLES
on a very simple configuration (for test-only
purposes):

1. Machine with IP-adddr = 192.168.0.200/24
2. Linux-Box with IP = 192.168.0.222/24
3. On the eth0 of the Linux-Box IP-Alias used = 
   #ifconfig eth0:1 192.168.0.225
4. NAT rules are:
   #
   iptables -t nat -F
   iptables -t nat -P PREROUTING ACCEPT
   iptables -t nat -P POSTROUTING DROP
   iptables -t nat -P OUTPUT ACCEPT
   iptables -t nat -A POSTROUTING -o eth0 -j SNAT --to 192.168.0.225
   #

Now, as I understand, it should be impossible to "telnet"
to the 192.168.0.222 address, as it can't pass through
POSTROUTING without mangling the sourse-ip. But it works
as usual. Both ip-addresses of Linux-Box are telnet'able.
It isn't correct, is it?

Thank you, 
Anton Antropov .