The Sysadmin’s Daily Grind: Arpalert

ARP WATCH

Article from Issue 73/2006
Author(s):

Corporate policies prohibit the unauthorized connection of hardware to the company network, threatening dire consequences in the case of non-compliance. Fair enough, but how do you actually go about catching somebody trying to plug an illegal laptop into your Ethernet?

My choice for a faithful watchdog is Arpalert [1]. Arpalert creator Thierry Fournier recommends the following incantation to send the beast off into the wild: ./configure --prefix=/usr/local make make install This series of commands puts the C program in /usr/local/sbin and the arpalert.conf configuration file in /usr/local/etc/arpalert. No Place Like Home For my initial experiments, I decided to use a network that gives me excellent visibility, such as the network in my home office. It’s the weekend, and my wife has gone down to the local library, so I shouldn’t have more than four of five computers on the network. I did the following to launch Arpalert: /usr/local/sbin/arpalert

Buy this article as PDF

Express-Checkout as PDF
Price $2.95
(incl. VAT)

Buy Linux Magazine

SINGLE ISSUES
 
SUBSCRIPTIONS
 
TABLET & SMARTPHONE APPS
Get it on Google Play

US / Canada

Get it on Google Play

UK / Australia

Related content

  • Perl: Monitoring MAC Addresses

    They say darkness is the friend of thieves, but the Perl daemon in this month’s column illuminates dastardly deeds, exposing hidden activities and alerting the admin when things seem to be going awry.

  • Charly's Column

    Incoming TCP connections do not always end up where they are supposed to. A freely configurable redirector points digital debris in the direction of a new and better place.

  • Charly's Column

    Using SQL to sift syslog data out of a database is an admittedly universal, but also fairly convoluted approach. phpLogCon, with its web interface, gives admins an easier option.

  • Charly's Column

    Some people don’t mind leaving traces of their IP address wherever they go, others prefer to use a tool like The Onion Router.

  • Charly's Column: GeoIP Lookup

    The global village is big enough to want to find out where your friend and enemies have set up camp. Charly offers a quick IP-based introduction to geography.

comments powered by Disqus

Direct Download

Read full article as PDF:

Charly_Column.pdf (87.03 kB)