Comcast Business: Speed Test

As a result of needing to do large file transfers, I ordered another line from Comcast on Tuesday. The technician (Josh) was really helpful in providing options where to correctly place the new router -- we ended up drilling a hole through the wall to drop a line into the garage.

Everything started to work 2-modem replacements later since the units he had along were swapped-out versions during the day or whatever was left in the pile before driving out in the morning. Of course, last night I decided that it would be better to keep the systems together and so transferred the modem back into the office.

The new SMC modem is DOCSIS 3 compliant and has 4-ports gigabit speed. That fact became more obvious when the FVS336G speed led lit up green (1000 Mbps) instead of amber (100 Mbps).

In terms of the feature interface, no changes at all apart from the fact that Full Speed 1000 Mbps is now available. Hmm, time to call Comcast Biz and get the other modem router replaced! Why? Well, see the speed test on that one under no load :-/

Ubuntu Tricks: Discover Network Connections

There will be many reasons you may want to get a map of connection points in a network. In my case I'd setup several VM's to use DHCP and wasn't sure which to connect to and work on from off-site. Enter nmap, a security auditing tool that does exactly what we want as just a tiny part of its functions.

First you'll need to have it installed:
$ sudo apt-get install nmap

Next, issue a scan and use a filter to get the relevant info, for example:
$ sudo nmap -sP 192.168.1.0/24 grep up
Host 192.168.1.1 appears to be up.
Host 192.168.1.100 appears to be up.
Host main (192.168.1.102) appears to be up.
Host main3 (192.168.1.103) appears to be up.
Host 192.168.1.168 appears to be up.
Nmap done: 256 IP addresses (5 hosts up) scanned in 2.548 seconds

In the above example:
192.168.1.1 is a router
192.168.1.168 is another router*
192.168.1.102 is a WinXP machine
192.168.1.103 is this machine

[*] Machines on the other end of .168 aren't shown as they are on a different subnet and we only scanned the 192.168.1.0/24 in this example. Explaining how to scan beyond the initial subnet would be beyond the scope of this tip. Use your favorite search engine for this. Always be extra careful to put a scope when you do a scan as this could be flagged as a precursor to a network attack by many of today's firewalls.

You can actually get a list of details (including MAC addresses, etc) using the '-vv' option. This would be perfect in locking down a network:
$ sudo nmap -vv -sP 192.168.1.0/24

If you're like me and would prefer a nice working GUI then look no further than zenmap. Similarly, download and install via:
$ sudo apt-get install zenmap

Have fun and safe discoveries!