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Port Blockage

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by russellrl2

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Due to the recent Windows RPC Vulnerability, ports UDP 135 and TCP 135, 137, 139, 445, 593, and 4444 were blocked. This is beyond our control. We are using Exchange 5.5 and prior to the blockage a user could logon to their laptop at home or in a hotel as if they were on the office network - connect to their internet provider - open the outlook set up on their laptop and access their email account just like they do in the office. This gives them more flexibility with their email account then accessing it through OWA. Since the ports were blocked they receive the following message when they open outlook "Your Microscoft Exchange Server is Unavailable". They can still access their account through OWA. I believe the problem lies with port 135 but am unsure how to fix it.

3 replies

by penguin netwerx

Is there a company VPN in place? If so, try having them connect to their ISP, then establish a VPN session, then check their Outlook mail. The VPN connection should bypass the port blockage issue, since once they're connected, it's almost the same as being on the internal net.

Also, there must be other ports blocked, since 25 and 110 are typically used for POP and SMTP. See if using the Exchange server's IP address instead of it's hostname makes a difference from the outside, unless it's behind the firewall and NAT isn't being used to reroute the traffic.

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