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| 6.3 |  | Troubleshooting Transport Layer Issues on Network Hosts |
| 6.3.5 |  | Gathering NetBIOS information |

Several tools are discussed in other modules for troubleshooting network problems, such as ping, ipconfig, and winipcfg. Some additional tools useful for gathering TCP and NetBIOS information are:

- netstat
- nbtstat

netstat is a command line utility that displays information on protocol statistics and current TCP/IP network connections. netstat supports IP, IPv6, ICMP, ICMPv6, TCP, TCPv6, UDP, and UDPv6, and can be used to display information for:

- All connections and listening ports running on the host
- Ethernet (Layer 2) statistics for the host, such as numbers of bytes, packets, and errors received and sent for the host.
- Port and address information for connections to and from the host
- Which connections the host initiated
- Per-protocol connection information
- Per-protocol statistics
- Routing table entries

netstat can also be configured to re-query and re-display information at a configured interval. By configuring netstat to re-query at intervals and directing this output to a text file, netstat can be used to build a profile of the behavior of the host TCP/IP transport layer operations over time.

nbtstat is a command line utility that displays information on protocol statistics and current NetBIOS connections running over TCP/IP. Unlike netstat, nbtstat is also able to interrogate remote machines for connection information.

Recall that NetBIOS uses a flat namespace, and that accurate NetBIOS name-to-IP address mapping is important for correct operation of a NetBIOS-based network. The functions of nbtstat are centered around reporting on and resetting the information in name tables on local machines, remote machines, and central NetBIOS name servers.