Anyone use nmap?
nmap is a open source tool for network exploration and security auditing.
You can use it to see who is on your network, among other things.
nmap -O 192.168.11.*
will return all connections that start with 192.168.11.
Out put looks like this:
Starting Nmap 4.68 (
Nmap - Free Security Scanner For Network Exploration & Security Audits. ) at 2009-01-01 20:59 CST
Interesting ports on buffalo.setup (192.168.11.1):
Not shown: 1711 closed ports
PORT STATE SERVICE
53/tcp open domain
80/tcp open http
2601/tcp open zebra
2602/tcp open ripd
MAC Address: 00:16:01
1
E:AE (Buffalo)
Device type: general purpose
Running: Linux 2.4.X
OS details: Linux 2.4.18 - 2.4.32 (likely embedded)
Uptime: 9.943 days (since Mon Dec 22 22:21:54 2008)
Network Distance: 1 hop
Interesting ports on 192.168.11.26:
Not shown: 1710 closed ports
PORT STATE SERVICE
80/tcp open http
139/tcp open netbios-ssn
9100/tcp open jetdirect
9101/tcp open jetdirect
9102/tcp open jetdirect
MAC Address: 00:16:35:48:A4:8A (Hewlett Packard)
Device type: printer
Running: HP embedded
OS details: HP Photosmart All-in-One (2575, PSC5100, C6100, or C6180), DeskJet 6940 or 6980, or OfficeJet 6300-series or L7600 printer
Uptime: 8.176 days (since Wed Dec 24 16:46:26 2008)
Network Distance: 1 hop
Interesting ports on 192.168.11.27:
Not shown: 1708 closed ports
PORT STATE SERVICE
23/tcp open telnet
80/tcp open http
427/tcp open svrloc
515/tcp open printer
1024/tcp open kdm
2000/tcp open callbook
9100/tcp open jetdirect
MAC Address: 00:15:99:01:9C:40 (Samsung Electronics Co.)
Device type: printer
Running: Dell embedded
OS details: 3Com OfficeConnect 56K LAN modem or Dell 1600n laser printer
Network Distance: 1 hop
Interesting ports on 192.168.11.50:
Not shown: 1709 closed ports
PORT STATE SERVICE
21/tcp open ftp
22/tcp open ssh
139/tcp open netbios-ssn
445/tcp open microsoft-ds
548/tcp open afp
631/tcp open ipp
Device type: general purpose
Running: Apple Mac OS X 10.4.X
OS details: Apple Mac OS X 10.4.8 - 10.4.10 (Tiger) (Darwin 8.8.0 - 8.10.2)
Network Distance: 0 hops
All 1715 scanned ports on 192.168.11.55 are filtered
MAC Address: 00:13:20:3C:87
B (Intel Corporate)
Too many fingerprints match this host to give specific OS details
Network Distance: 1 hop
Interesting ports on 192.168.11.56:
Not shown: 1711 closed ports
PORT STATE SERVICE
135/tcp open msrpc
139/tcp open netbios-ssn
445/tcp open microsoft-ds
641/tcp open unknown
MAC Address: 00:0E:A6:54:71:47 (Asustek Computer)
Device type: general purpose
Running: Microsoft Windows XP|2003
OS details: Microsoft Windows XP SP2 or Windows 2003 Small Business Server
Network Distance: 1 hop
Interesting ports on 192.168.11.100:
Not shown: 1712 closed ports
PORT STATE SERVICE
80/tcp open http
2601/tcp open zebra
2602/tcp open ripd
MAC Address: 00:16:01
2:63:0A (Buffalo)
Device type: general purpose
Running: Linux 2.4.X
OS details: Linux 2.4.18 - 2.4.32 (likely embedded)
Uptime: 79.348 days (since Tue Oct 14 13:40:03 2008)
Network Distance: 1 hop
OS detection performed. Please report any incorrect results at
Nmap OS/Service Fingerprint and Correction Submission Page .
Nmap done: 256 IP addresses (7 hosts up) scanned in 75.585 seconds
With a little knowledge of my network, I can tell exactly which devices are on the network, including networked printers, network bridges, and computers with their OS listed.
The list above tells me my wife's PC running Windows XP SP2 is on, her son's Dell is on, my Mac is on, the wireless bridge is up and running, two printers are on, Samsung and HP, and the Buffalo router is on also.
If security such as WEP or WPA or Leap is used, it is difficult for an outsider to use your internet. It takes a considerable effort to break the key and get it. It is just not worth it to get free internet access.
Also, some routers allow MAC address filtering. It allows you to list devices by their MAC addresses that you specifically allow access. This alone will block any neighbor. However, the WEP key, etc, encrypts your wireless traffic so no one can read it. It is very wise to enable encryption on a wireless router.