Studying for test

• You might want to go over the POST codes, SCSI types, LCD aspect ratios. Also, what files are needed to install XP, and what files will be found in the root directory of XP. Go over the operating system upgrade paths. Go over 802 project models, OSI model. What is CSMA/CD? CSMA/CA?  Review fiber optic connectors.
• Also, firewalls, program filtering, port filtering.

Misc “Numbers" You Should Know

• 1294 parallel port. 1394 Firewire. 802.11x where x=a, b, g, or n (proposed) Wireless. A is 5gHz. Others are 2.4. 802.3 ethernet.

Hardware and BIOS Operations

• IRQ’s http://www.helpwithpcs.com/upgrading/change-irq-settings.htm
• IRQ assignment. First are the BIOS-configured IRQ’s.
• IDE primary 14, secondary 15. LPT1, LPT2, are 7, 5. Floppy is 6. Com 1 and 3 are 4, 2 and 4 are 3. See pg http://www.helpwithpcs.com/upgrading/change-irq-settings.htm
• See Device Manager > View Resources by Connection, or see Programs >Accessories > System Tools > System Info.
• See http://www.pagesbydave.com/GEO/APLUSQUEST1.HTML#DDD
• XT systems had only IRQ numbers from 0-7. Had a single irq chip. AT system added second chip, 8 more hardware interrupts. On AT they made IRQ 2 on the first chip, a gateway  to cascade to the interrupts on the second chip, and interrupts 8-15. The second interrupt on the second chip, IRQ 9, cascades from the third interrupt on the first chip, IRQ 2.  Originally IRQ 2 was used for VGA. Now VGA uses 9? My Device manual says 9 is for ACPI (Advanced configuration power interface). My gigabyte Sys Info screen says that 9 is SCSI-RAID host controller and that the video card is IRQ 16. However generally, don’t manually config 2 or 9. IRQ priority: originally lower to higher (0 to 7). Now second chip replaces IRQ 2, so sequence is now 0, 1, 8, 9, 10, 11, 12, 13, 14, 15, 3, 4, 5, 6, 7. Lower numbers have higher priorities. This is in contrast to scsi priorites, where higher numbers tend to have higher priorities.
• Check out IRQ number for a particular computer at device manager, or System Info. Look for resources. On gigabytemb, acpi and scsi-raid share IRQ 9.
• IO memory addresses, also called port address, or IO ports, are used for io access by a device, rather than for storage of data. Ea address is a 32 bit number. 8 nibbles; 4 bytes. Each nibble is 4 bits. Each byte is 8 bits. 8 hexadecimal digits. Ea hex digit represents a nibble, 2 hex digit represents a byte. First 4 hex digits are zero. So to remember the address for each port, you only have to remember the last 4 hex digits of each port. (That means highest possible port number is FFFFh, 65535 in decimal – 650k bytes). IO address ranges have starting points and ending points (just 8 or so larger than starting point). Just a small range for IO. Not the same as mapping memory, which is a relatively large area of computer memory used as a buffer by the peripheral. A periphal may use both, an IO address, and buffer addresses. See book page 617.
• Decimal, hexadeximal, binary. 4 binary digits equal 1 hex digits. So 2 hex digits equal an 8-bit byte.

Operating System Comparisons

• Only NTFS partitions support file encryption and folder encryption. Copy such a file from ntfs to fat32 and it will lose its encryption. Same with re to compression.
• File cannot be both encrypted and compressed. However an encrypted file moved or copied to compressed folder, becomes compressed.
• Fat32 uses smaller cluster size than FAT 16 (also called FAT).
• Fat16 supports max partition size of 2 gb. Restricts number of entries in root folder.
• FAT32 supported by win 95, 98, osr2, ME, 2000, and xp. NT and linux can not be on fat 32. Fat 32 max 8 terrabytes.
• FAT16 and FAT32 permits folder sharing NTFS supports file-level security.
• Linux reads FAT16 and ntfs but not fat32?
• Floppies use FAT12

Op Sys	Fat 16	Fat32	NTFS
Win95a	y	n	n
Win95b	y	y	n
Win 98	y	y	n
Win ME	y	y	n
Win NT4.0 w sp4	y	n	y
Win2000	y	y	y
XP	y	y	y

Windows Installation, various versions

• Hardware requirements for various Op Sys
• For XP you need a pentium and cpu operating at min 233Mhz recommended 300 Mhz
• Interestingly win 2000 pro needs Pent 2
• RAM 64 mb is very minimum, 128 mb recommended.
• Free hard disk space 1.5G or more.
• XP requires a 2 gb hard drive and 650 mb of disk space. RAM 64 mg recommend 128. VGA 800 x 600 or better.
• Checkupgradeonly will check your hardware. It is on the installation cd.
• CD ROM or DVD ROM.
• SuperVGA or better. (800 x 600). Mouse.
• Vista needs 1 ghz processor. RAM 512 mb. 20 g hard drive with 15 g space.
• DirectX 9 graphics and 32 MB of graphics memory
• Admin acct and password is set up during gui mode of op sys install.
• Win 9x has io.sys, msdos.sys, config.sys, command.com, autoexec.bat
• Windows 9x. multiboot config determned by msdos.sys
• NT and XP and 2000 require ntldr (no extension!), boot.ini, ntdectect.com – in root directory (of “system” partition, really the boot partition.)
• Booting the op sys:
• File invloved:
• A file called ntldr, in the the root directory, accesses the file system on the boot drive.
• If file named hiberfil.sys is found in the root directory (hiberfil.sys is a hibernation image), its contents are loaded into memory and the system resumes where it left off.
• Otherwise, the op sys reads boot.ini and if prompts the user to make a choice from the boot menu. If there boot.ini has only one operating system listed, that sys can be configured so that the boot menu doesn't display, and the file for that system automatically gets loaded.
• If a non NT-based OS is selected, then ntldr loads the file associated with the operating system chosen via boot.ini (bootsect.dos if no file is specified or if the user is booting into a DOS based OS) and gives it control.
• If an NT-based OS (such as windows) is selected, then ntldr runs ntdetect.com, which gathers information about the computer's hardware.
• If ntdetect hangs during hardware detection there is a debug version called ntdetect.chk which can be found on Microsoft support.
• Then ntldr starts ntoskrnl.exe (usually c:\windows\system32\ntoskrnl.exe), passing to it the information returned by ntdetect.com.
• Windows 2000 network protocols include appletalk, nwlink, netbeui.
• Nt has “disk administrator.”
• Ntfs, fat32, cdfs (for cd’s)
• Virus cannot infect a cd or dvd - by itself. However if a user unknowingly, or intentionally, burns a cd with a set of files that includes a virus, then the virus can obviously get onto the cd.
• Op sys upgrade paths. See pg 271. 2000 you can upgrade to it from all but ME. XP, you can upgrade from all but Win 95.
• Network install. Boot to network. Boot from cd w net drivers then map net drive to share that has installation files and then run winnt32 from there. Or
• Preboot execution environment (if network card is pxe compatible) allows you to: when booting you’ll see F12 to boot from network, this uses existing window dhcp server to allocate address to network card then loads trivial ftp service  and others then downloads files automatically from predetermined network share that’s been config with service for windows 2000 server that will perform rest of installation for you. Bigger thruput than even DVD. Fast. Unattended by using an sif file.
• File and application data wizard works for config for multiple users?
• Upgrade as opposed to full installation, retains program etc.
• Barts boot disks: http://nu2.nu/bootdisk
• You can boot from win98 then sw cd’s to win xp cd and run winnt32 from that. DOS smartdrv (RAM cache) will make install go faster.
• Whatever name you put in during installation is legally liable re licensing issues!
• Network settings: custom settings. Domain setting rarely works from client computer network setting screen. Use peer workgroup instead.
• Automated and Remote installation.
• Remote Installation Services. RIS.  Connect to 2003 server machine. Network install.
• Or 2, use setup manager, setupmgr.exe, to create unattended installation batch file. On installation disk or your copy on hard drive, find tools\deploy.cab. Or it may be c:\support\tools\deploy.cab. Grab all subfiles form deploy.cab and put in windows dir?
• Makes unattend.txt answer-file or you may use another name. Run setupmgr.exe. Use with cd, ris, etc. Ans questions in program screens here, once, instead of multiple installation screens.
• Installation via hard drive imaging uses sysprep plus third party imaging program (norton Ghost). With Vista, 3^rd party pgm is no longer needed. Uses sysprep.exe and sysprep.inf is the answer file used with sysprep.
• Use norton’s Ghost to…create a drive image. Or other drive image software. Later fix ip address. Then fix CID (computer identifier). Thing to do is after making image use MS utility called sysprep which takes image and strips out uniqueness.
• For sysprep info see http://technet.microsoft.com/en-us/library/bb457073.aspx
• also http://support.microsoft.com/kb/302577
• FAT16 largest partition is 2G Fat 32 with win 95 release 2
• Terrabyte is 1000 gigabyte.
• BIOS > POST (beep error msg, text error msg) > CMOS > MBR > OSRECORD > NTLDR (bootstrap loader). Once ntldr is found, BIOS terminates. See A-plus book pg 312. For POST info see system startup troubleshooting. POST, initialization (from CMOS?), boot (Osrecord, ntldr?)

Operating System Aspects

• SMBIOS, System Management BIOS, part of bios responsible for reporting configuration data to diagnostics programs. Such as the DMI program that came with your gigabyte mb?
• Driver signing defaults, to make sure device drivers have been signed, or not, can be changed at Computer  > Properties > Hardware Tab > Driver signing button.

Registry

• Win 98 system.dat, user.dat,
• In Windows XP, 2000, and 2003 there are several Registry files. These files are named without a file extension and are stored in the Windows\System32\Config folder. These files are named Software, System, SAM, Security, Default, and UserDiff. There is one more Registry file and it does have a file extension, NTuser.dat. In Windows XP, 2000 and 2003, NTuser.dat is stored in the users profile folder under the Documents and Settings folder. Each user has their own NTuser.dat file. The NTuser.dat file stores all settings that each user selects; these settings will override settings stored in the System file.
• Each registry file corresonds to a registry hive.

 

• BIOS cmos generally has 2 kinds of passwords, supervisor and user. User allows user to get into computer, at boot. Supervisor allows them to get into cmos.
• Allowing full control to a user, for a folder, enables user to do whatever he wants to files and folders within, no matter what his level of permissions for those files and folder.
• Permissions are assignable by the “owner” of a file. Whoever created the file. Groups and users that are given permissions are called “security principals.” They are put on an access control list in the form of an access control entry.
• Smart cards. They use EAP authentication (Extensible Authentication Protocol). An example of an EAP auth protocol is EAP-TLS – EAP Transport Level Security. CHAP does not support smart cards. PAP password authentication Protocol uses plain text password to authenticate. CHAP is encrypted password but not used with smart card.
• System Info is msinfo32.exe. First tab is “system summary.”
• Memory devices, flash drive uses usb, secure digital flash memory. SDF can use drive bay device or “external card reader.”
• Start Menu. Sorting it in Windows 2000 is different than XP. There is a button for it in Taskbar Properties, instead of doing R-click > Sort. Get to taskbar prop via Start > Settings > Taskbar prop, instead of R-click taskbar > Prop.

Backups

• Backing up a file as part of a full backup, or incremental backup, sets its archive-please bit to 1, archive-please. It is normally called the archive bit but I call it the archive-please bit. A file marked with this bit is not a file that has been marked as being archived, it is a file that has been marked as needing to be archived.
• Full backup sets the bit to zero, for every file backed up (sometimes described as “clears the archive bit”). If files are subsequently changed, their archive-please bit will be set to 1 again (“sets the archive bit”).
• Incremental backup will see this and back  them up, that is, incremental will back up any files that have changed since full backup. It also sets their archive-please bit to 0, thus indicating they are archived and do not need to be archived again unless they are changed. At next incremental backup a new incremental backup file will be made. There will be a full backup file, an a number of incremental backup files.
• Differential backup backs up changed files, however it does not set their archive-please bit to zero. Therefore at next diff backup, files archived after the original full backup, are still marked as archive-please, and will get backed up again. Everything since full backup gets archived again. However there will only be 2 backup files, the original full backup file, and only one differential backup file.
• Copy avoids changing archive bit.

Memory Dumps

• Virtual memory: Unless you have at least 2 Mb of virtual memory, on boot volume, you won’t be able to do any sort of memory dump. (2mb is very little.) For pagefile efficiency, you can have most of your virtual mem on another volume. Memory dump is useful debugging file.
• Three kinds of memory dump: Complete, Kernel and Small memory dump (64 KB). See Overview of Mem Dump File Options
• Complete shows all system RAM in event that computer stops unexpectedly. This includes kernal memory, and all the processes that were running. Requires paging file (virtual mem) that is, 1, on the boot volume and 2, sufficient to hold all the physical RAM plus 1 megabyte (MB). Complet dump is not available if computer is 1, running a 32-bit operating system and 2, has 2 gigabytes (GB) or more of RAM. Overwrites previous files; won’t append
• Kernel (the mose useful?) mrecords only the kernal memory and HAL hardware abstraction layer. Requires approx between 150MB and up to 2GB of pagefile size. Overwrites previous files; won’t append
• Small memory dump. Requires 2 mb on boot volume. This is the only kind that can make a new file with each news stop. Special folder with history of these files. Can be renamed but is generally %SystemRoot%\Minidump. Sequence of files is made, all with the extension *.dmp.
• You can load complete memory dumps and kernel memory dumps with standard symbolic debuggers, such as I386kd.exe. I386kd.exe is included with the Windows 2000 Support CD-ROM. Load small memory dumps by using Dumpchk.exe. Dumpchk.exe is included with the Support Tools for Windows 2000 and Windows XP. You can also use Dumpchk.exe to verify that a memory dump file has been created correctly.
• MS recommends creating page file on all disk volumes, but esp on volumes on other drives and on drives on other controllers, than the boot partition. The virtual memory algorithm will give preference to drives that are less frequently used for data.
• Sigverif.exe can be used to check system files (and others) for digital signature from MS. Makes a log file sigverif.txt.

Users, Groups, User Profiles

• Users and Groups Section 1, main user-group config: Start > Run > Control userpasswords brings up same screen as Control Panel > Users Accounts. Simple user and group gui.
• Users and Groups Section 2, advanced user and group config: Start --> run --> control userpasswords2 goes to screen where you can create users with different permissions  I don’t know of any other way to get here than via Start > Run. Here, like in Control Panel > User Accounts, you can add users, remove them, config properties, and what groups they belong to. More users listed than at Control Panel > User Accounts. From the advanced tab you can add username-passwords combinations for users of other networks, including web site users. Takes you to same place as My Computer > R-click > Manage > Local Users and Groups > users.
• Users and Groups Section 3, Local Users and Groups snap in: Once at Control userpasswords2, also on the advanced tab, there is a button that will take you to good old Local users and Groups. You can also get to local users and groups from an mmc snapin. There is one preconfig, under Start > Administrative Tools > Computer Management. You can also get there from R-Click My Computer > Manage. If computer is member of domain and joined to a domain, Local Users and Groups snap in will be unavailable. These seem to do everything that control userpasswords2 can do, and more, so I don’t see much point in using control userpasswords2.
• Users and Groups Section 4, User Profiles: From My Computer > Properties > Advanced Tab > User profiles section > Settings button, you can get to configure user profiles for the users of the computer. This includes disk directories where user profiles are stored, and there is a check box for roaming profiles, which is relevant if user is a domain user and a roaming profile has already been set up in active directory.

Sharing And permissions

Share permissions

• Share permissions are the only way to secure network resources on FAT and FAT32 volumes, because NTFS permissions are not available on FAT or FAT32 volumes.
• Share folders and files applies to folders only (and all files under it). You can not make a file a network share, only a folder.
• Share has 3 permissions, Full, Change, and Read.
• Standard share permission when you make a folder shared is making it Read, for Everyone. However everyone is not added to the NTFS security permissions. If you add a new user, his/her Share permissions are set to allow Read. His or her NTFS security permissions are set to everything checked off. To give users more, you need to explicity give them permissions.
• No advanced permissions.

NTFS permissions

• There are 6 basic NTFS security file permissions, and 7 folder permissions. The file permissins are Full, Modify. Read and Execute, Read, Write, Special.  Folder permissions have an additional permission, List Folder Contents.
• Add a new folder or add a new file, and its ntfs security permissions may or may not be inherited from folder above it, depending upon inheritance choices made.
• 14 advanced permissions.

Remote Desktop and Remote Assistance

Remote desktop

• The computer that is being accessed is called the server, and the computer that accesses it, the client. Sybex calls them remote and home respectively. The server comptuter is also called the “terminal server.”
• The server must have XP Pro on it. The client (home computer) needs only XP Home. The server computer is running Remote Desktop. The client computer is running Remote Connection.
• However your XP Home computer (server) can be accessed with Remote Assistance from another computer (client). If you are at this “server” ou can ask for help with it, by sending an “invitation” to a client to please help me. A client can also initiate an offer of help. Ask for help, invite help, via MSN messenger or email msg. Ask for help at Start > All programs > remote assistance invitation. Or go to Help and Support > Invite a friend to do Remote Assist. Offer help by Help and Support > search for Offer Remote Assist. You may have to explicitly enable Local Comp Policy > Comp Config > Admin Template > System > Remote Assist > Offer Remote Assist > Enable. And click Show and  put name (on server) in. Don’t forget to do gpupdate. And possibly enable Solicit Remote Assist on the server computer.
• But Remote Assistance is a bit different than remote desktop. Configure remote assistance in My Comp > Prop > Advanced > Remote tab. Remote Desktop is config here too.

General Windows Op Sys Troubleshooting

• Generally preference order for fixing problems is safe mode, boot to last known good config, ASR, Recovery console. ASR does the recovery console automatically.
• To install Win 2000 or Win XP recovery console:  c:\i386\winnt32.exe /cmdcons. Or you can run Recovery Cons directly from Windows installation CD.
• ASR (automated system recovery). For asr to work, you’ll have to have first made an ASR backup, using the backup program). Backup makes a backup to a tape or hard drive, plus makes a special floppy that you put in during boot.
• You’ll be given choice to press F6 as CD boots. You cannot find this ASR F6 choice if pressing F8 to load windows in safe mode. Similar thing re running recovery console choice from cd.
• ASR will run from CD. You may need to config cmos to boot from cd.
• You may need to do a registry setting so that you can use recovery console wo a password. I did. This setting is explained in my Compaq Win XP notes.
• ERD or emergency repair disk was used in windows 2000 and earlier. It is a floppy. No longer used. ASR used instead.s
• Virus, worm, Trojan.
• Virus relies on other programs to function. It is not embedded in software like a trojan is, however it relies on the other program to make it work. Trojan is embedded in an application program. Worm is self-contained progam that does not require support of other programs.
• SNMP, Simple Network Management protocol. Runs as a service. You can configure it there. But to see its output you need a program that is not installed on xp automatically. It is however in windows support tools.

System startup troubleshooting, BIOS, Windows

• POST Power On Self-Test. Codes http://8.6.223.13/hardware/beepcodes.shtml
• http://www.brainbell.com/tutors/A+/Hardware/_POST_8212_Power_On_Self_Test.htm

 

POST Display codes
100 to 199 - System boards
200 to 299 – Memory (RAM)
300 to 399 - Keyboard
400 to 499 - Monochrome display
500 to 599 - Color/graphics display
600 to 699 - Floppy-disk drive or adapter
700 to 799 - Math coprocessor
900 to 999 - Parallel printer port
1000 to 1099 - Alternate printer adapter
1100 to 1299 - Asynchronous communication device, adapter, or port
1300 to 1399 - Game port
1400 to 1499 - Color/graphics printer
1500 to 1599 - Synchronous communication device, adapter, or port
1700 to 1799 - Hard drive and/or adapter
1800 to 1899 - Expansion unit (XT)
2000 to 2199 - Bisynchronous communication adapter

2400 to 2599 - EGA system-board video (MCA)

3000 to 3199 - LAN adapter

4800 to 4999 - Internal modem

7000 to 7099 - Phoenix BIOS chips

7300 to 7399 - 3.5-inch disk drive

8900 to 8999 - MIDI adapter

11200 to 11299 - SCSI adapter

21000 to 21099 - SCSI fixed disk and controller

21500 to 21599 - SCSI CD-ROM system

• SMKMCF: sysboard, mem, keyboard, mono, color, floppy. 100,200…600. 900 parallel port.

Networking Basics

• Link light, activity light.
• OSI Model 7 layers PDNTSPA
• Physical, Datalink, Network, Transport, Session, Presentation, Application.
• Physical Layer
• Datalink layer. Data frame. Size spec. Has info abt from addreess and to address (MAC addresses, within same subnet) ,  info to physical, system for deciding which packets go and which don’t go. Picks packets from those sent from multiple devices. Decides which to send to phys layer. Card and drivers.
• Network layer. Provides network-wide addressing. Routing packets. Decides where to send packet. IP protocol is an example. Network addresses used for multiple networks. TCP/IP software.
• Transport layer. End to end communication and reliable data delivery. Also called Host to host layer. Has the TCP portion of TCP/IP. UDP. Segment info into packets at the size spec by data link layer. Ethernet packet size 1500 bytes incl crc. Also error detection and possibly error correction. Isolates upper layers from details of transfer. Doesn’t know if below are  ether link or token ring or what. Most likely app presentation and session are a single application. For example web browser. Protocols – connection oriented or connection-less. Connection-Oriented: connection established. Packet sent, acknowledged. If packet lost it’s resent. Data goes back and forth in a tracked and sequenced manner. Data transfers. TCP. SPX (netware). Connection-less: no connection made. If packet is lost, it’s not resent. Broadcast or announcement packet. UDP, IPX.
• Session. Net Bios. Netware Core protocol Manage and track user sessions. Windows: Workstation and Server Service Software. Netware: Redirector, requestor. These days, the Windows client for Netware.
• Presentation layer: common data formatting between communication devices. MIME prototocol. Multipurpose Internet Mail. Makes sure receiving station can receive data sent by transmitting station. MIME resides inside email client. Eudora? Part of workstation and server service software if you are connecting to shared files and printers.
• Application layer: gives end user applications (such as MS Word?) access to network resources. The actual applications do not include the application layer. Application not in MS Word, but rather, in windows, in Workstation and Server Service Software (Windows), Windows Client for Netware (Netware).  “Network client” protocol generally does functions of all of the top 3 layers, application, presentation, and session.
• 90 percent of troubleshootng is in bottom 4 layers. P, D, N, T.
• Types of LAN’s and connections
• MAU in regard to token ring topology is a Multistation Access Unit. MAU in regard to 10Base-5 thicknet ethernet is a Media Access Unit, or Ethernet transceiver, which connects to the coax cable (in a physical bus topology) with a vampire tap. The MAU connects to the NIC with DB-15 style connectors called DIX or AUI connectors.
• Cable. 10BaseT requires cat 3. 100BaseT, cat 5. 1000baseTX, cat 5e.
• All 3 work up to 100 meters. 328 feet.
• Fiber optic connectors. See http://www.timbercon.com/Fiber-Optic-Connectors/index.html
• More fiber optic connectors. See http://www.thefoa.org/tech/connID.htm

ST. Bayonet (twist and lock) full size. S- Twist, ½ twist

SC. Snap in, full size. S- Click. Ceramic ferrule.

LC. Snap in. SFF (small form-factor). Little Click

FC. Screw on (twist until snug). Full size.  Much like ST but screw twist, not bayonet twist. Ceramic ferrule

MT-RJ. Snap in. 

• All used with either multimode or single mode fiber cable
• ARP: address resolution protocol. Used to associate MAC address with IP address.
• Netsh allows you to configure network paramaters, much like the Network connections window does. Netsh is used from the command line.
• Wireless Application Protocol, different than Wireless Access Point, is a protocol used by wireless devices, generally mobile ones such as phones. Both abbreviated WAP. Wireless Application protocol is a protocol for wireless devices like phones, like http is a protocol for computers. WTLS is to Wireless Application Protocol as TLS is to http-https-html. (Hypertext transfer protocol, markup lang).

Routing

• static routing: network admin writes in routing tables.
• Dynamic routing: “route discovery protocols,” routing protocols, get info from other routers.
• Two categ of dynamic routing, distance vector and link state.
• Distance vector routing includes RIP (routing Information Protocol) for TCP/IP and RIP for IPX.
• Link state is faster and more efficient. Multicast or unicast rather than broadcast. As a last resort Open Shortest Path First (OSPF) is used; performs a database synchronization (every 30 min).
• Two Link State Routing protocols that are of the link state kind (a kind of dynamic routing protocol) are: Netware Link Services Protocol (NLSP, for IPX) and Open Shortest Path First for TCP/IP (for TCP/IP).
• Networking Protocls: routable and non-routable see table 2.4 on pg 74 of Net Plus book (NetBEUI isn’t routable.)

Modem commands

• AT (ATtention) commands. Developed by Hayes, used universally. AT followed by A-Z or &A - &Z. ATDT nnnnnnn, Dial Tone. Then the number. ATA, answer mode, off-hook. ATH0: switch-Hook mode, hang up mode. Allows for using AT commands. ATH1: off-Hook, auxilliary relay. AT&F, set to factory defaults, including S-registers. ATZ resets defaults but not S-registers. ATSn=x: changes s-register n, to x. Sn?: read s-reg n. ATI: identify modem. AT&x: additional set of commands using A-Z.
• S registers. S0: number of rings to answer on. S8: pause time for dial-comma. Result codes: 0, OK, command executed; 1, CONNECT, connection has been established; 2: RING, ring detected. 158: CONNECT 33600/ARQ/V34

Wire Troublehooting Tools

• Time Domain Reflectometer. Only need one end of wire to test for quality of continuity. Shorter wire will take less time to reflect signal. Estimate how far away the break is.

Wireless Ethernet

• Private key, same key encrypts and decrypts. Also known as symetrical.
• DES is Data Encryption Standard A private key encryption sys.
• WEP, a private key sys, is Wireless Equivalent Privacy, deprecated security system.
• Two methods of authentication can be used with WEP: Open System authentication and Shared Key authentication. Due to some esoteric technical flaws it’s entirely possible for an eavesdropper to intercept enough WEP-encrypted packets to eventually deduce what the key is. WPA (WiFi Protected Access) certification program to indicate compliance with security protocols. It addressed WEP’s shortcomings. Temporal Key Integrity Protocol (TKIP), was added to WPA. For encryption. TKIP is a required part of WPA. There is also AES encryption. It is stronger than TKIP. And optional. The easiest-to-use and most widely supported version is WPA Personal, sometimes referred to as WPA Pre-Shared Key (PSK). To encrypt a network with WPA Personal/PSK you provide your router not with an encryption key, but rather with a plain-English passphrase between 8 and 63 characters long. Using TKIP, that passphrase, along with the network SSID, is used to generate unique encryption keys for each wireless client. And those encryption keys are constantly changed. (Although WEP also supports passphrases, it does so only as a way to more easily create static keys, which are usually comprised of the hex characters 0-9 and A-F).
• Note that although WPA is an encryption method, in Windows prop sheet for the wireless adapater in your computer, you will find it listed in the authentication drop down box, as opposed to in the encryption drop-down box, where it should belong. Afer selecting it, you’ll be given a choice of tkip or aes.
• In the linksys program, wep and wpa will be listed in a drop down box labeled “security.” Linksys also has Radius and LEAP. Choice of tkip or aes will be listed on next page (after you press Next). Also, if you chose wpa, (wep?) will you be given choice of authentication method (added security, in addition to encryption), shared key (this is a pre-shared key) or open system. WPA-person (wps-psk) has no such choice, but wpa-enterprise has many choices, including tkip vs aes. LEAP and RADIUS also have many choices. In the win program, you will have several varities of wpa to choose from (but no LEAP or RADIUS choice), all with tkip and aes choices.
• Router has choice only of WEP or WPA-PSK (WiFi Protected Access Pre-Shared-Key).
• The “windows security” dialog box is the box that shows first when you press ctrl-alt del, and you are in user log-off mode (single user mode). Here you have a choice of lock, log off, shut down, task manager, etc. In multiple user mode, Windows Task Manager comes up right away.
• Only a cpu and monitor should be connected to a 500 va watt ups.

Security

• You can send someone to a phony website more easily if they are using a hyperlink to get to the site, instead of putting the address into the address bar. Users usually don’t look at the actual address, in the status bar or wherever. The actual link can be to a page that is different than the name of the link. This is called “hyperlink spoofing.”
• Malware. Worm gets tranmitted over network, replicating on one comupter after another.
• Boot virus is malware that infects boot sector on hard disk. Prevents hard disk from booting.
• Email virus: spread thru email.
• Trojan: not spread thru network insecurity, but rather by people trading infected programs, that otherwise may be working programs. You need to execute the program, for the trojan to be installed. Will damage programs or data on the computer.