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Routing setup question
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Routing setup question
Hi all,
I have a rather unusual setup in that I would like to connnect to two different networks at the same time and I am curious how to set up the routing. The network has the characteristic that DHCP based addresses are allowed through the firewall to access the outside world (in my case case, I need to access new firmware images and antivirus definition files at a minimum) while fixed IP addresses are blocked by the firewall. All of the users of the NAS are located within the firewall and using a fixed IP addresses if very convenient as there are clients that use AFP, SMB, and NFS. While AFP and SMB can use zeroconfig and don't really need a fixed address, the linux machines using NFS require it. My question is thus can I configure my two ethernet ports in such a way that the first ethernet port is connected via DHCP while the second is connected via a fixed IP (IPv4) address. This would seem to require that all addresses of the form xxx.xxx.0.0/16 are directed to the network interface configurated with a fixed IP address while everything else is directed to the DHCP configured network interface. My question is then, how do I configure the routing to achieve this? Thanks for help in advance.
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Re: Routing setup question
Just to clarify- it sounds like you are wanting to connect both NICs to the same network, not different ones. Is that correct?
I'd look first at the DHCP server, not the NAS. Many let you allocate a specific address for a specified MAC address, which gives you the benefit of a consistent IP address, but still using DHCP. This feature has a few names (for instance Address Reservation, ARP binding, MAC address binding). If your server has this feature, then that would be the best approach.
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Re: Routing setup question
To answer your question, yes both NICs would connect to the same network. I have an allocated fixed IP that is supported by the DNS system that I would like to use if at all possible, hence the question about the routing question. In particular, I just wish to have all of the Netgear OS requests funnelled to the DHCP port while leaving the fixed IP address accessible for connections. I will check on the possibilities of using a reserved DHCP as a stop gap method, but this would have to be implemented on the ReadyNAS side. Going back to the original question, is it possible to route most traffic through the DHCP NIC while accepting requests on the fixed IP NIC? For instance, on MacOS, it is possible to set interface priorities so that requests are forwarded to a particular interface with higher priority while other interfaces are fallen back upon when necessary. On my Mac Pro I have the fixed IP set for the highest priority so that I can connect via the gigabit connection to the local area network and by leaving the router field empty for the gigabit connection NIC, requests for outside my subnet are automatically forwarded to the (slower) DHCP WiFi NIC. Is something like this possible for the ReadyNAS?
Thank you for your help.
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Re: Routing setup question
@paul137 wrote:
I will check on the possibilities of using a reserved DHCP as a stop gap method, but this would have to be implemented on the ReadyNAS side.
Reserved DHCP would need to be done in the DHCP server, not the ReadyNAS.side. The ReadyNAS is just set up to use normal DHCP. It would give you internet connectivity plus give you a fixed IP address, giving what you need with a single network connection. But if you need to use the DNS address for some reason, I guess that won't help (though generally it is nice to have known IP addresses for servers).
@paul137 wrote:
For instance, on MacOS, it is possible to set interface priorities so that requests are forwarded to a particular interface with higher priority while other interfaces are fallen back upon when necessary.
Linux allows for that also, but the ReadyNAS application does not. You can set up a static route, but you can't set an interface metric.
What you'd need to do is use the DHCP address on the first NIC, which should handle the internet traffic requests, and use the second NIC for DNS. Inbound traffic will of course be accepted on either NIC. This isn't a usual configuration (normally the IP addresses would be set up on different subnets, unless they were configured to use link aggregation). I'm not sure if it will work reliably or not.
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Re: Routing setup question
I came up with another solution as I could not use the reserved DHCP address approach. I defined the first interface as DHCP and the second as the fixed IP address. I then left the router field blank for the fixed IP address so that packets destined outside the subnet (building) the server is in will not be forwarded using the fixed IP port (which seals off alot of the internal network from accessing the machine, but since users are in the building, this should be a fine solution. Do you see any problems with this implementation? It seems to respond correctly to the fixed IP for devices on the same subnet while at the same time the OS access to the firmware server, etc. is working fine as well.
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Re: Routing setup question
@paul137 wrote:
... I defined the first interface as DHCP and the second as the fixed IP address. I then left the router field blank for the fixed IP address ... Do you see any problems with this implementation?
FWIW, I believe that linux (by default) will give priority to eth0 over eth1. I suspect that's why your configuration works (and I believe it would fail if you reversed the config on the two interfaces).
I also suspect that filling in the gateway field on the static address won't change the behavior - but if this is specific to enabling local NFS, it might be wise anyway, since you do want to keep NFS use limited, because it isn't a secure protocol.