| Port No | 139 |
| Service Name | NETBIOS Session Service |
| RFC Doc | 0 |
| Protocol | UDP |
| Description | A principle rqmt for NetBIOS services on MS hosts (Win9x/ME/NT/Win2000). TCP 139 is used for directory replication, event viewer, file sharing, logon sequence, pass-thru validation, performance monitoring, printing, registry editor, server manager, trusts, user manager, WinNT Diagnostics, and WinNT Secure Channel.Security Concerns: Key target in auth & DOS attacks, plus sniffer capture of sensitive data transfers. Block at all perimeters; NIC-filter on public-exposed MS hosts |
| Reference Link | Port Information |
| Attack | No |
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