How to access devices with static IPs on different subnet than router?

Question

I have a SonicWall TZ100, firmware SonicOS Enhanced 5.8.1.13, with a static subnet of 10.0.6.0/24 on X0. Ports X2-X4 are port shielded to X0. On ports X3 and X4 I have two devices that were moved from different locations and we forgot to update their settings while on site. Their IPs are 192.168.213.254 and 10.0.4.253. I'm not sure which one is connected to which port.

What do I have to do on the SonicWall to gain access to the web interfaces of those devices so I can change their IPs? I don't have physical access to the devices which is why I'm trying to do this remotely.

I tried assigning the X3 and X4 ports with static IPs of what the gateways for those devices should be, but it didn't help so I reverted it back. Help would be appreciated.

One is a Canon ImageRunner 3235 and the other is a time clock. — Gup3rSuR4c, Sep 30 '13 at 19:29
Right, I do not think it is possible, unless you create subnets on these port to match their ips. — Danila Ladner, Sep 30 '13 at 19:48
That's what I tried to do, but it didn't work. I'm wondering if there's a routing configuration I have to do to make the subnets talk to each other? — Gup3rSuR4c, Sep 30 '13 at 20:37
And was the router IP address for the 192.168.213.x device and the 10.0.4.x device? — hookenz, Oct 16 '13 at 20:48
You will need to add a the old router address as ip alias' on your router and ensure they can NAT out. then you should be able to reach them. — hookenz, Oct 16 '13 at 20:54

score 1 · Answer 1 · answered Feb 03 '15 at 14:51

I'd approach this in a totally different way: Configure a PC (laptop) with 3 IP addresses: 192.168.213.250 and 10.0.4.250 and an address on the new subnet. connect the two devices and the laptop on the same VLAN. (no firewall, just (an isolated) hub/switch or direct connect cable) just connect to the old IP adres and start reconfiguring.

Then change your laptop back to DHCP client.

In cases where I don't even know the IP address of the network device, I connect directly with wireshark capturing with an arp filter. Most of the time, the device does an gratious arp, and then you know the IP.

score 0 · Answer 2 · answered Sep 30 '13 at 21:23

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Can you remote into a server or desktop that is on the same subnet as these other devices? if so, you can add an IP address that would be on the same subnet as the devices that you are trying to access.

answered Sep 30 '13 at 21:23

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score 0 · Answer 3 · answered Oct 16 '13 at 20:38

Set up X3 and X4 interfaces with the IP address of the old gateway. (Ex: If the device 10.0.4.253 connected to X3 has a gateway such as 10.0.4.1, setup the X3 interface with the IP 10.0.4.1. Try to ping the devices then. Also, put those interfaces in the LAN zone to avoid firewall rules blocking your pings while you are testing.

How to access devices with static IPs on different subnet than router?

3 Answers3