Admin Magazine

Any user on a LAN can sniff and manipulate local traffic. ARP spoofing and poisoning techniques give an attacker an easy way in.

Security experts are always concerned with WLAN access points, but they sometimes forget that the client is also open to attack. Public hotspots make it quite easy for attackers to hijack connections, as the Hotspotter tool demonstrates.

In last month’s issue of Admin Workshop, we introduced tools that help admins get services up and running. This month, we will show how you can use the Ident protocol to associate a user name with a TCP connection.

The Radius protocol is typically used to authenticate users in dial-up scenarios. But Radius is also useful in LAN environments: in combination with 802.1X, Radius forces users to authenticate at a low level before the switch opens up a port.

On vacation we may be happy just to check the position of the sun,but computers need a more accurate measure of time. Luckily, there are atomic clocks that can receive time signals by radio and off the Internet.

Wireless networks are practical but dangerous at the same time.WEP encryption is unlikely to stop an attacker. But help is at hand in the form of add-on security measures such as an encrypted OpenVPN tunnel.

Firewalls are typically implemented as routers,but it doesn’t have to be that way. Bridging packet filters have a number of advantages,and you can add them to your network at a later stage without changing the configuration of your network components.