04.28
The Techs that Drive Tech
NAME
dmidecode – DMI table decoder
SYNOPSIS
dmidecode [OPTIONS]
DESCRIPTION
dmidecode is a tool for dumping a computer’s DMI (some say SMBIOS) table contents in a human-readable format. This table contains a descrip
tion of the system’s hardware components, as well as other useful
pieces of information such as serial numbers and BIOS revision. Thanks
to this table, you can retrieve this information without having to
probe for the actual hardware. While this is a good point in terms of
report speed and safeness, this also makes the presented information
possibly unreliable.
The DMI table doesn’t only describe what the system is currently made
of, it also can report the possible evolutions (such as the fastest
supported CPU or the maximal amount of memory supported).
SMBIOS stands for System Management BIOS, while DMI stands for Desktop
Management Interface. Both standards are tightly related and developed
by the DMTF (Desktop Management Task Force).
As you run it, dmidecode will try to locate the DMI table. If it suc
ceeds, it will then parse this table and display a list of records like
this one:
Handle 0×0002, DMI type 2, 8 bytes. Base Board Information
Manufacturer: Intel
Product Name: C440GX+
Version: 727281-001
Serial Number: INCY92700942
Each record has:
A handle. This is a unique identifier, which allows records to refer
ence each other. For example, processor records usually reference
cache memory records using their handles.
A type. The SMBIOS specification defines different types of elements
a computer can be made of. In this example, the type is 2, which
means that the record contains “Base Board Information”.
A size. Each record has a 4-byte header (2 for the handle, 1 for the
type, 1 for the size), the rest is used by the record data. This
value doesn’t take text strings into account (these are placed at the
end of the record), so the actual length of the record may be (and is
often) greater than the displayed value.
Decoded values. The information presented of course depends on the
type of record. Here, we learn about the board’s manufacturer, model,
version and serial number.
OPTIONS
-d, –dev-mem FILE
Read memory from device FILE (default: /dev/mem)
-q, –quiet
Be less verbose. Unknown, inactive and OEM-specific entries are
not displayed. Meta-data and handle references are hidden. Mutu
ally exclusive with –dump.
-s, –string KEYWORD
Only display the value of the DMI string identified by KEYWORD.
KEYWORD must be a keyword from the following list: bios-vendor,
bios-version, bios-release-date, system-manufacturer, system-
product-name, system-version, system-serial-number, system-uuid,
baseboard-manufacturer, baseboard-product-name, baseboard-ver
sion, baseboard-serial-number, baseboard-asset-tag, chassis-man
ufacturer, chassis-type, chassis-version, chassis-serial-number,
chassis-asset-tag, processor-family, processor-manufacturer,
processor-version, processor-frequency. Each keyword corre
sponds to a given DMI type and a given offset within this entry
type. Not all strings may be meaningful or even defined on all
systems. Some keywords may return more than one result on some
systems (e.g. processor-version on a multi-processor system).
If KEYWORD is not provided or not valid, a list of all valid
keywords is printed and dmidecode exits with an error. This
option cannot be used more than once, and implies –quiet.
Mutually exclusive with –type and –dump.
-t, –type TYPE
Only display the entries of type TYPE. TYPE can be either a DMI
type number, or a comma-separated list of type numbers, or a
keyword from the following list: bios, system, baseboard, chas
sis, processor, memory, cache, connector, slot. Refer to the DMI
TYPES section below for details. If this option is used more
than once, the set of displayed entries will be the union of all
the given types. If TYPE is not provided or not valid, a list
of all valid keywords is printed and dmidecode exits with an
error. Mutually exclusive with –string.
-u, –dump
Do not decode the entries, dump their contents as hexadecimal
instead. Note that this is still a text output, no binary data
will be thrown upon you. The strings attached to each entry are
displayed as both hexadecimal and ASCII. This option is mainly
useful for debugging. Mutually exclusive with –quiet and
–string.
-h, –help
Display usage information and exit
-V, –version
Display the version and exit
DMI TYPES
The SMBIOS specification defines the following DMI types:
Type Information
0 BIOS
1 System
2 Base Board
3 Chassis
4 Processor
5 Memory Controller
6 Memory Module
7 Cache
8 Port Connector
9 System Slots
10 On Board Devices
11 OEM Strings
12 System Configuration Options
13 BIOS Language
14 Group Associations
15 System Event Log
16 Physical Memory Array
17 Memory Device
18 32-bit Memory Error
19 Memory Array Mapped Address
20 Memory Device Mapped Address
21 Built-in Pointing Device
22 Portable Battery
23 System Reset
24 Hardware Security
25 System Power Controls
26 Voltage Probe
27 Cooling Device
28 Temperature Probe
29 Electrical Current Probe
30 Out-of-band Remote Access
31 Boot Integrity Services
32 System Boot
33 64-bit Memory Error
34 Management Device
35 Management Device Component
36 Management Device Threshold Data
37 Memory Channel
38 IPMI Device
39 Power Supply
Additionally, type 126 is used for disabled entries and type 127 is an
end-of-table marker. Types 128 to 255 are for OEM-specific data.
dmidecode will display these entries by default, but it can only decode
them when the vendors have contributed documentation or code for them.
Keywords can be used instead of type numbers with –type. Each keyword
is equivalent to a list of type numbers:
Keyword Types
bios 0, 13
system 1, 12, 15, 23, 32
baseboard 2, 10
chassis 3
processor 4
memory 5, 6, 16, 17
cache 7
connector 8
slot 9
Keywords are matched case-insensitively. The following command lines
are equivalent:
dmidecode –type 0 –type 13
dmidecode –type 0,13
dmidecode –type bios
dmidecode –type BIOS
FILES
/dev/mem
BUGS
More often than not, information contained in the DMI tables is inaccu
rate, incomplete or simply wrong.
AUTHORS
Alan Cox, Jean Delvare
SEE ALSO
biosdecode(8), mem(4), ownership(8), vpddecode(8)
dmidecode February 2007 DMIDECODE(8)
Environmental Benefits
Is this a green solution? It can be if you take into consideration of adding smaller, low-power devices to your network instead of full-blown computers. Two companies I can recommend for the clients are Diskless Workstations and devonIT. The noise reduction factors switching to diskless clients can be amazing. Another option that may have some green factor to it is using that older machine that is sitting in your basement or garage (we all have them) instead of throwing it away. Keep an eye on power consumption if you choose to use older equipment, though.
Centralization Benefits
If you have several independent computers, problems quickly develop. Files become scattered over every machine you touch. Where was that brilliant resume you sent out last month that got such positive response? These random files require an intensely complex backup routine and will be difficult to track. The problem of having different versions of files also comes into play. By keeping it all on one server, you are making things much simpler.
Time Benefits
You spend what seems like countless hours updating your systems with the same fixes over and over if you don’t “go thin”. While it is commendable to treat each system with individual attention and know each system, do you really want to spend all your free time updating? This goes along the lines of centralization, but there is a time benefit when you have only one server to upgrade.
Cost Benefits
Thin Clients are much cheaper. You can expect approximately 350-500 dollars per machine for decent hardware. Configured correctly, the performance of these machines can rival high-end $1000+computers. Touching back on the centralization, some cloud computing backup providers and backup application vendors charge you per computer. It makes so much more sense to have one backup target.
These are the benefits that have made me come to the conclusion to create a PXE environment. I will, of course, move slowly and make sure all the steps are done properly, but the advantages have out weighed other factors at this point.

Logo 1: I want to avoid the whole Matrix clone thing, but the Matrix was cool...

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During a traffic audit, it becomes very critical to know exactly what you are looking at. I often refer to this document. A very important consideration to those new to the field: IANA does not enforce these assignments. They are only here to be the official registry. Just because you see a specific port being used, doesn’t absolutley mean that port is carrying it’s assigned traffic. Worms will often use well-known ports to disguise themselves. Rule of thumb: always analyze the packets, don’t just assume based on the port.
The Ubuntu Forums are very valuable as a reference tool. It always helps to read an entire thread before implementing things, due to the assistanceit provides being user-generated content. It saved numerous reinstalls when I first started using Ubuntu.
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The name says it all with this one. Debian has a strong library of resources to learn how to implement solutions and resolve problems in this distribution.
This is the default place I look for domain owner information. It is always handy to have access to this in a situation where your customers are using third party services that provide specialized solutions.
Do you have any suggestions for any other sites that help make your day as an IT Admin? Please feel free to suggest your own favorites in the comments section.
Results oriented methodology is taking over our small little world. Users and managers are no longer amazed by bells and whistles. They need technology, but not in the feature-driven approach that worked ten years ago. Potential of a product is not as important as fullfilling immediate needs. The features have to take care of everyday issues, not something they will experience when they are the big dog on the block. Reporting is very important. Success of products from salesforce.com, Siebel, Remedy, and Oracle have paved the way for a great deal of accountability with regards to the employee-employer relationship and the Information Technology department is no longer immune. Utilization is a strong requirement with limited budgets.
What can be done to adjust to the cycle we are currently in? There are many ways to thrive.
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A heart-to-heart may be needed with management and ultimately the people you support. Environments that have a long standing history of doing it themselves will have a hard time with being told how and where to save their files, and there will even be some people that have a workable system. The key is to get as many people on board as possible. Let them participate in the filing system planning to prove to them you have their and the company’s needs in mind. When you are new to a network, always be sure to perform a rundown of all user accounts to make sure all home drives have been provided and are mapped correctly. The last thing you want is to have your customers question sincerity because they are feeling overlooked.
Running a quick check of applications running on the network and the drawbacks of forcing that data onto a shared drive can also reduce the number of backup targets.
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While on my routine stumble-around this morning, I located a coffee table book that is suitable for the technologist in all of us. Call me strange. I get excited about new technology and new ways of doing things, but I also enjoy learning how we got to this age of constant beeps, digitizing everything we used to touch, and having friends all over the world. Core Memory is a collection of very artistic photographs from the Computer History Museum by photographer Mark Richards and author John Alderman capturing computer history and presenting it in a very artful way. This one will definitely be on my coffee table next to my Irish history books and Chicago Architecture books. Click here to check it out on Amazon.
Mark and John discussed this project in 2007 at Google. Here is the video from this event:
He has approached you about his extensive mp3 collection of music from the late 1960s. The nearest department superstore (the only hardware source in the area) from his cabin is a 50 mile drive and he doesn’t enjoy making special trips for his computer. He wants his music to be dependable and accessible at all times at the cabin, but he also doesn’t want Internet access. The computer will be wired into his home speaker system so he can listen to it while entertaining and relaxing. He wants to be able to pull up a media center screen and build easy playlists.
What do you suggest to him with regards to hardware and software?