Problem switching SonicWALL Pro 2040 to new IP address block

Networking/Security Forums -> Firewalls // Intrusion Detection - External Security

Author: billyverde PostPosted: Thu Mar 10, 2011 9:30 pm    Post subject: Problem switching SonicWALL Pro 2040 to new IP address block
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Hello,

We are running a SonicWALL Pro 2040 Standard with firmware version 3.1.0.7-77s.

Iím running into problems when I try to switch this unit over to a new IP address on a new block (and a new switch) weíve been assigned. Essentially, when I change the IP address, subnet mask, and default gateway under Network -> Settings all activity on our network ceases. Even stranger is the fact that the two servers already plugged in to this new switch and operating normally on the new IP address block lose Internet connectivity when the SonicWALL unit is plugged in to the switch.

When I change these settings back to those on our old IP block (and on a different switch), everything returns to normal.

Iíve plugged my laptop into the same port on the switch and had no problems connecting to the Internet when I use these exact same network settings, and Iíve verified that there is no IP address conflict on the network.

Restarting and power cycling the SonicWALL unit after moving it to the new switch/IP block does not make a difference. Which is weird, because I can plug a laptop into the new switch, configure it with the firewall's new IP/netmask/gateway info, and it gains connectovoty fine.

And I've tried pinging the new default gateway under System -> Diagnostics, and I get a 'timed out' error.

Might there be some security setting or something that Iím missing? The only changes Iím making are the IP address, subnet mask, and default gateway (DNS servers remain the same).

Any input at all would be welcome.

Thanks!

Moderator note: edited subject to add relevant keyword - capi

Author: capiLocation: Portugal PostPosted: Thu Mar 10, 2011 9:45 pm    Post subject: Re: Problem switching Pro 2040 to new IP address block
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billyverde wrote:
Even stranger is the fact that the two servers already plugged in to this new switch and operating normally on the new IP address block lose Internet connectivity when the SonicWALL unit is plugged in to the switch.

That suggests either an IP or a MAC address conflict. Is your Sonicwall perhaps configured to do proxy arp? Is there something special about the IPs of these two servers, e.g. are they per chance covered by a route on the Sonicwall through another interface?


billyverde wrote:
And I've tried pinging the new default gateway under System -> Diagnostics, and I get a 'timed out' error.

I would try plugging the Sonicwall into the laptop, and running a packet capture on the laptop (e.g. tcpdump or Wireshark). Set the laptop up as though it was the default gateway (give it the default gateway's IP and netmask) and repeat the test. See what you receive on the laptop end. If unable to reproduce the problem, try setting the laptop's MAC address to the same as the default gateway's.



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