NetBIOS Ports 137, 138 and 139 all necessary for NetBIOS communication (firewall)?

NetBIOS Ports 137, 138 and 139 all necessary for NetBIOS communication (firewall)?

Post by Peter Bla » Thu, 08 May 2003 19:17:42



When I setup a NetBIOS (over TCP/IP) communication are ALL the three Ports 137, 138, 139 necessary for this connection ?
Or can a NetBIOS session be established without one of the mentioned ports?

As another view: Can I close one of these ports in my firewall but still be able to communicate over NetBIOS (over TCP/IP).

Thanks
Peter

 
 
 

NetBIOS Ports 137, 138 and 139 all necessary for NetBIOS communication (firewall)?

Post by Peter Bla » Thu, 08 May 2003 19:58:01


When I setup a NetBIOS (over TCP/IP) communication are ALL the three Ports 137, 138, 139 necessary for this connection ?
Or can a NetBIOS session be established without one of the mentioned ports?

As another view: Can I close one of these ports in my firewall but still be able to communicate over NetBIOS (over TCP/IP).

Thanks
Peter

 
 
 

1. Firewall rejecting port 137 netbios-ns

I'm not sure if this is bind related or not, and I can't seem to search for
numbers in the list archive.

I see the following in my firewall log every so often.  But I don't see any
corresponding "input" logs.  

Packet log: output REJECT eth1 PROTO=17
     63.205.225.170:64961 165.87.156.173:137
     L=78 S=0x00 I=16956 F=0x0000 T=127 (#42)

So either I'm allowing access to something by mistake, or some service I'm
allowing access to is sending on UDP 137.  Is something in bind sending out
these packets?

If it is bind, then what triggers it?

Bill Moseley

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