safe to open port 445 (MSFT DS)?

[Happo]

I have an issue that has now occurred in three new computers w/dialup. XP Pro, McAfee Internet Security Suite 6.0. It is not an isp or spyware issue. Dialup access is fine for approximately 3 - 9 hours, it varies depending on usage. Then everything just times out, although according to Windows it is still 'connected', (blinking monitors are there but not blinking). In the firewall event log there are continuous entries
2004/10/02 00:32:20 [My ip address]:3956 (dialup-[ip address].acc08-[username]-mel.comindico.com.au) 203.220.83.200:445 Microsoft-DS
About every 10 - 15 seconds records like the one above appear. How can I stop this, is it a firewall issue?
Thanks in advance,
Daniel.

 

[bcastner]

It is safe to open the port to a LAN subnet, but block it on your WAN connection.

As I am guessing you are not on a LAN, go ahead and have your firewall block the following if it does not already:

. Microsoft file sharing SMB: User Datagram Protocol (UDP) ports from 135 through 139 and Transmission Control Protocol (TCP) ports from 135 through 139.

. Direct-hosted SMB traffic without a network basic input/output system (NetBIOS): port 445 (TCP and UPD).

Check too that your dialup ISP does not have an inactivity logoff. If that kicked in you would still be "connected" but no longer authenticated. I would throw this freeware on the system and see if the issue improves:

http://www.gammadyne.com/conkeep.htm