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mikebw at bilow.bilow.uu.ids.net (Mike Bilow) writes: > Since NetBEUI is inherently unable to be routed, I would assume that > it tends to be fairly secure by default. This is very different > from TCPBEUI, which obviously can cross routers. I can't really > imagine anyone running a TCP/IP LAN without a firewall these days, > and I'm not so sure that the firewall has to be quite that fascist. I run a TCP/IP LAN at home and I don't have a firewall. But I'm probably more the exception than the rule. I believe that we can secure machines such that firewalls are no longer necessary. Indeed, I believe that such security is available today, if people use it. > You're something of an expert on security, so I may as well ask: if > the firewall simply blocks all inbound traffic referencing ports > 137, 138, and 139, what risk is there to a TCPBEUI LAN? Are there > any legitimate reasons for traffic from the public referencing these > ports to cross a firewall? I must admit that my personal resolver doesn't expand "BEUI". I also don't know enough about the internals of netbios to know if it uses any ports other than the 137-139. I *suspect* that blocking those ports on the firewall (both incoming *AND* outgoing) _should_ effectively block netbios, but it's always possible for someone on the inside to open up holes to people on the outside. Security, of course, depends on your threat model. FYI: Much of my information about SMB is from CIFS, which is based on SMB. CIFS is MicroSquish's vaporware marketing to battle WebNFS (which actually exists). > netbios-ns 137/tcp NETBIOS Name Service > netbios-ns 137/udp NETBIOS Name Service > netbios-dgm 138/tcp NETBIOS Datagram Service > netbios-dgm 138/udp NETBIOS Datagram Service > netbios-ssn 139/tcp NETBIOS Session Service > netbios-ssn 139/udp NETBIOS Session Service > # Jon Postel <postel at isi.edu> > > DA> N1NWH > > I didn't know you were a ham! Are you ever active on the Boston repeaters? Used to be active on the MIT Repeater. Ocassionally I was on .23, but that was a few years ago. > -- Mike, N1BEE -derek -- Derek Atkins, SB '93 MIT EE, SM '95 MIT Media Laboratory Member, MIT Student Information Processing Board (SIPB) URL: http://web.mit.edu/warlord/ PP-ASEL N1NWH warlord at MIT.EDU PGP key available
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