Linux - NetworkingThis forum is for any issue related to networks or networking.
Routing, network cards, OSI, etc. Anything is fair game.
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I have two interfaces on my machine, and what I need to do is to close off eth1 using iptables due to that interface connecting directly to the DMZ on the router. (Snort is listening on the interface, and thats the interfaces only purpose)
The other interface is eth0 and is connected via the router. This is the interface that is to have no restrictions on it at all.
When I use iptables iptables -i eth1 -A INPUT -j DROP. I cannot get a network connection when this rule is in use. The webserver on the box allows no connection and email is not collected, Even though eth1 is specified. Could this be because the system is trying to use eht1 over eth0, if so how can I tell thesystem to use eth0?
Just to be clear:
Eth0 Protected network connection. No constraints or controls are needed.
Eth1 Snort interface, connected to DMZ, needs stealth
Originally posted by MaverickApollo they are both using 255.255.255.0 eth0 ip is 192.168.1.5 and eth1 is 192.168.1.4
If I was to put them on different subnets it would not work would it? The rest of the network is using a subnet of 255.255.255.0.
It won't work this way..What you can do is
1) use different subnets for the cards and leave 255.255.255.0 netmask
2) divide 192.168.1.0/255.255.255.0 into two subnets, one for every interase (requires change of one of the IPs)
Could you tell us what you're trying to do with this config?
Mara is absolutley correct. The Linux Stack will not allow multi-homing of interfaces (unless you are load-balancing, in which case both NICs have the same IP). If two NICs are in the same subnet, Linux will only use one of the interfaces to respond, reguardless of which interface the request came in on. Which can obviously casue problems. Time for some networking 101. Seperate your networks and enable routing if you need to communicate between them.