Îãðàíè÷åíèÿ ïî IP

Çàäà÷à:
Âûäåëèòü ãðóïïó IP, íàïðèìåð:
192.168.1.10 - 192.168.1.19, êîòîðûì áóäåò èç 4õ äîñòóïíûõ ñåòåé äîñòóïíû òîëüêî 3.
192.168.1.20 - 192.168.1.255 äîñòóïíà òîëüêî 4-ÿ ñåòü, áåç îñòàëüíûõ.

Èìåþ:
1-ÿ ñåòü: ñåòü äîìîâàÿ, êîòîðàÿ ïîëó÷àåòñÿ îò ìàðøðóòèçàòîðà WL-500gP (192.168.1.255)
2-ÿ ñåòü: ëîêàëüíàÿ ñåòü, ê êîòîðîé ïîäêëþ÷¸í ìàðøðóòèçàòîð (172.20.255.255)
3-ÿ ñåòü: ÷åðåç âòîðîé ìàðøðóòèçàòîð (172.20.1.2) â ýòîé æå ñåòè (172.20.255.255), êîòîðûé èìååò äîñòóï ê äðóãîé ñåòè 10.255.255.255
4-ÿ ñåòü: èíòåðíåò ÷åðåç ïåðâûé ìàðøðóòèçàòîð (172.20.1.1) â ñåòè

Ðîóòèíã äëÿ ñåòåé 10.255.255.255 ïðîïèñàí â òàáëèöå ìàðøðóòèçàöèè íà øëþç 172.20.1.2
172.20.1.1 âûñòàâëåí êàê îñíîâíîé øëþç

Destination____Gateway_______Genmask______Flags______Metric__Ref__Use_____Iface
172.20.1.1_______*_______255.255.255.255___UH_________0______0____0_____WAN vlan1
192.168.1.0______*________255.255.255.0_____U_________0______0____0_____LAN br0
172.20.0.0_______*_________255.255.0.0______U_________0______0____0_____WAN vlan1
10.0.0.0_____172.20.1.2_______255.0.0.0_____UG_________1______0____0_____WAN vlan1
default______172.20.1.1________0.0.0.0______UG_________0______0____0_____WAN vlan1

Âîïðîñ:
Ñ ïîìîùüþ ÷åãî ýòî ìîæíî ñäåëàòü (WEB èíòåðôåéñ èëè ðó÷êàìè â êàêîì-òî ôàéëå)?
È, åñëè íå òðóäíî, îáúÿñíèòå íà ïàëüöàõ :)