Why is there no access to the local network from under the wifi subnet?

Question

Domain Name System

There is a main local network for the company (there will be NETWORK "A") and a wi-fi subnet is created (NETWORK "B")
For these purposes, a gateway is created on centos 6.4 (dhcp, caching dns and iptables turned off FOR THE TIME)
eth0: external NETWORK A
192.168 .1.251/24
gw 192.168.1.3 (gateway to KERIO in LAN)
eth1: internal NETWORK B
192.168.2.1/24
gw 192.168.1.251
iptables disabled
/etc/sysctl.conf forwarding enabled
internet distributed via dhcp (eth1),dns working , the traffic passes all,
but except for the gateway 192.168.1.3 from network B, nothing is seen and nothing is pinged
, what could be the problem?

Answer 1

In order for packets to go between networks A=192.168.1.0/24 and B=192.168.2.0/24, you need a gateway connected to both of these networks (two and interfaces) and having IP addresses in both of these networks. For example gwA=192.168.1.251 and gwB=192.168.2.251.
In order for the gateway itself to know which networks it is connected to, it needs routes:
192.168.1.0/24 dev ethX (without a gateway)
192.168.2.0/24 dev ethY (without a gateway)
(usually they are set automatically when configuring the interface, but you never know what )
In order for the gateway to know how to reach all other networks (except A and B), it needs a route
0.0.0.0/0 via some thread of the gateway located in network A
In order for nodes in network B to see network B itself, they need a route :
192.168.2.0/24 dev ethX (auto interface route)
In order for nodes in network B to see network A, they need a route:
either 192.168.1.0/24 via gwB (if only network A is needed)
or 0.0.0.0/0 via gwB (if network A has access to the Internet)
NB: gwB is located on network B and is therefore visible due to the interface route.
In order for the nodes of network A to see network B, they need a route:
192.168.2.0/24 via gwA
NB: gwA is located in network A and therefore is visible due to the interface route.