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Getting management data out of WMI from Linux can
be challenging but rewarding. This article discusses some of the common
techniques that are used to achieve this purpose.
Although Microsoft would prefer you to use Active
Directory for implementing domain-wide Group Policy, the legacy NT Domain
policy system still works for Windows XP, Server 2003, and all of the older
platforms. This means that organizations who login to a Samba or NAS server
with Windows networking protocols can still get the benefit of Windows
domain policies for certain types of system and user behavior, without
running Active Directory.
Few people know it, but Windows has the built-in ability
to generate SNMP traps from Eventlog messages, thereby allowing you to
monitor for critical events such as login failure, pending drive failures,
and other major problems that may otherwise go unnoticed. Here's how it
works.
Denial-of-Service attacks are unfortunately somewhat
commonplace in this day. Here is a quick guide to understanding how to
prepare for these attacks, and how to respond when they inevitably occur.
In order for IP-enabled systems to communicate with
each other on the same network, they must first be able to identify the
hardware addresses of the other devices. This service is provided by the
Address Resolution Protocol. Other ARP services include providing an IP
address via Reverse ARP (RARP), advertising a new IP address via Gratuitous
ARP (GARP), checking for duplicate addresses via DHCP-style ARP, and more.
IP can be thought of as being like a national delivery
service that gets packages from a sender to a recipient, with the sender
being oblivious to the routing and delivery mechanisms used by the delivery
agent. The sender simply hands the package to the delivery agent, who then
moves the package along until it is delivered. That's also how IP works:
a system creates an IP datagram, drops it into the network, and leaves
it up to the intermediary IP devices to deliver the datagram to the destination
system.
IP is an unreliable protocol, and as such, delivery
is not guaranteed to occur. However, sometimes a problem crops up that
will prevent all datagrams from getting through to their destination. When
these kind of non-transient errors occur, IP uses the Internet Control
Message Protocol (ICMP) for informing the sending system of the problem,
so that it can inform the user or application of the fatal error.