I’m not sure I understand what you’re trying to express. Do I understand you correctly that:
[ol][li]the UCS machine will have two network interfaces, one with the address 192.168.1.10 and one with the address 192.168.2.1[/li]
[li]other machines from the network 192.168.1.0/24 should use a Squid web proxy installed on the UCS machine to access the intern?[/li][/ol]
If so this is rather straight forward:
[ul][li]Install UCS and configure both network interfaces[/li]
[li]Set the default gateway to your router’s address[/li]
[li]Follow the documentation for installing and configuring Squid[/li][/ul]