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Firewall Attack Help !!

Posted on 2004-10-12
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Last Modified: 2013-11-16
Help, my Firewall is detecting that IP Address 193.108.87.93:6184 has a target Destination of : 192.168.1.255:137 UDP.

There are no custom filters setup on my Firewall to point traffic to that address and I dont have PC with an address of 192.168.1.255.  When I ping 192.168.1.255 on my LAN I do get results returned.  But I definatley dont have a printer, device or anything else.

Whats going on !!!
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Question by:Northumberland
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Chris Dent earned 2000 total points
ID: 12285230

192.168.1.255 is the Broadcast address for a 24 bit subnet (192.168.1.0 255.255.255.0).

Port 137 is the NetBIOS Port, broadcasts are all sent to that 192.168.1.255 address - this port should be blocked on your firewall, there's no need for external devices to Broadcast in your subnet.

The Broadcast Address is seen by everything on your Subnet.
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LVL 71

Expert Comment

by:Chris Dent
ID: 12285242

*edit* Should read: Broadcasts from the Subnet 192.168.1.0/24 are all sent to the 192.168.1.255 address.

For an external device trying to access that port it could be any of someone Port Scanning or perhaps a Virus (on the remote computer).
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Author Comment

by:Northumberland
ID: 12285262
So Chris should I clode port 137 anyway ?
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LVL 71

Expert Comment

by:Chris Dent
ID: 12285370

In my opinion no one will need to get to Port 137 Externally, equally Port 137 will not need to go outside of your network. So it should be closed. on the Firewall.
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Author Comment

by:Northumberland
ID: 12302936
Thanks Chris
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