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Difficulties with Sonicwall TZ170 --> SMTP

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6 replies

by crane

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Hello all,
I have some difficulties with setting Firewall for port 25.
Network schema:
router -> firewall -> server
Router: WAN: Fixed IP 84.xxx.xxx.xxx
LAN: 192.168.2.2
Firewall: WAN: 192.168.2.1 (NAT)
LAN: 192.168.1.254

Problem is regarding receiving email from my ISP on port 25(Exchange Server). I thing that there is a problem with firewall setting but even if I set "Allow ALL from WAN to LAN"
I can not telnet on port 25. Have you any suggestion how to overcome this?
Many thanks.Crane

6 replies

by fregeus

but i'm having difficulty putting my finger on it.

Did you setup another IP on your segment 192.168.2.x for your smtp server? If the firewall itself is not the smtp server, then the connection should not go to it (ie 192.168.2.1).

My guess is that you need to configure a NAT statement that says, for example, 192.168.2.3 NAT to then open the port 25 on IP 192.168.2.3.

Let me know if this helps.

TCB

by crane

Thanks for replay,
My Exchange server is on address 192.168.1.1
My default gateway is 192.168.1.254(Soniwall LAN address) than it's translate to 192.168.2.1(Sonicwall WAN) and forwarded to router. So the way from LAN to Internet is working properly, but not the other way.
If you need any other information please send me the details.
Thank you.

by fregeus

Your Sonicwall needs to have an external IP address, unless your router can NAT. If your router can NAT incoming communication, you need to have an IP on the 84 segment translated to a 192.168.2.x network.

If your router cannot NAT, then you need to put the sonicwall in place of the router so it can have an address on the 84 segment and an IP on the 84 segment for your smtp server.

I'm not sure i'm explaining this right. In order to receive communications from the Internet, you need to have an IP, other than your primary router IP, that can act as your SMTP server external address. Then you need to translate that address and allow smtp traffic for that address.

Do you understand?

TCB

by crane

Many thanks,
I checked configuration on router and NAT wasn't set. The router is UPnP and if you are using network wizzard on SBS (without Sonicwall) it will change setting on router. So I unmarked UPnP and set NAT on 84.xxx.xxx.xxx translated to 192.168.2.x and it works. So the problem wasn't on a Firewall but on the router.
Now I'm ashamed that I didn't find the problem my self. Thank you again.

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