I am trying to telnet into our SonicWall email security appliance for testing purposes. I can access the appliance using telnet (telnet emailappliance.mycomapny.com 25) from two other remote networks with out any problem. However, when I try to connect from my home network I cannot connect. I get the error "Could not open connection to the host on port 25. Connect failed." I've tried disabling my firewall and antivirus. I connected a computer directly into the cable modem to bypass the router. I've tried this on two different computers running Windows 7 Professional. What am I missing?

Hi, First, I would like to verify other two remote networks are internal network or external network. Generaly, the external port for the telnet is closed on the SonicWall email security appliance. You need to contact Dell support to configure the exrternal port or use VPN to connect the internal network, then use telnet. Niki Han TechNet Community Support

The remote networks are external, completely separate. I can connect to the ESA via telnet on port 25 from these two different remote external networks. This tells me the firewall is allowing the connection. Interestingly, from my home network I can telnet to towel.blinkenlights.nl successfully but I can't to the ESA. So why can I telnet from home to one location but not to the ESA? The firewall? And if the firewall is blocking the telnet connection to the ESA why can I connect from the other two remote external networks?Jason Rule MCP, MCSA, MCTS

Hi, Could you give me the topology of your network situation? (Home---Internet---SonicWall---ESA?) Meanwhile, please check if there is any inbound filter on Sonicwall. Niki Han TechNet Community Support

Thank you for your reply. The topology is as follows: Home---Internet---Sonicwall---ESA There are no inbound filters on the SonicWall ESA.Jason Rule MCP, MCSA, MCTS

Hi, The issue may be caused by the DNS resolution. Could you ping emailappliance.mycomapny.com successfully from your home network? Best Regards Scott Xie

Yes I can ping it. I also tried to make the connections using the IP address and got the same result. I can telnet in from other remote networks but not my home network. I've checked my home router settings, even connected my laptop straight to the cable modem. I've turned off my firewall and antivirus. Still no joy. What's strange is I can telnet to towel.blinkenlights.nl successfully from home. I'm stumped.Jason Rule MCP, MCSA, MCTS