You are currently browsing the monthly archive for May, 2008.
Wi-Fi technologies defined by IEEE 802.11b/g/n are operated in the frequency 2.4 GHz, in which the 2.4 GHz spectrum is divided into 14 overlapping. The available channels that are use in a particular country is different according to the regulations of that country. In the United States, for example, FCC regulations only allow channels 1 through 11 to be used. In Europe channels 1–13 are licensed for 802.11b operation (with 1, 5, 9 and 13 usually deployed). In Japan, all 14 channels are licensed for 802.11b operation. In the following tables, we listed the channel ID, central frequency of each channel for each regulatory domain.
Here are some channels for 802.11b/g
Channel Id Freq in MHz America Europe Japan Other
1 2412 * * * *
2 2417 * * * *
3 2422 * * * *
4 2427 * * * *
5 2432 * * * *
6 2437 * * * *
7 2442 * * * *
8 2447 * * * *
9 2452 * * * *
10 2457 * * * *
11 2462 * * * *
12 2467 * * *
13 2472 * * *
14 2484 *
Larger Address Space
Compare to IPv4, IPv6 increases the number of address bits by a factor of 4, from 32 bits to 128 bits. Studies conducted sat the 128 bits IPv6 address will lead to aproximately 1000 address per person on this planet.
Simplified Header Format
The IPV4 header fields Header Legth (IHL), identification, Flags, Fragment offset, header checksum, and padding fields have been removed in IPv6. This removal results in faster processing of the basic IPv6 header.
The options field of IPv4 is changed in IPv6 and is now managed by an extention header chain. The majority of the other fields were either not changed or changed only slightly. In addition to a smaller number of fields, the header is 64 bits aligned to enable fast processing by current processors.
Hierarchical Network Structure
in IPv6, hierarchical addressing is used to optimise routing and improve the efficiency of the network. A basic IPv6 principle is the minimal processing routers along the way should do. The IANA allocates each regional internet registry or RIR a number of prefixes to fulfill their needs. RIR`s then allocate smaller prefixes to the LIR`s that in turn allocate prefices to their customers. All IPv6 prefixes then, are provider asigned. Contrary to what exists for IPv4, Independent, are not provided.
Mandatory IPsec Implementation
IPSec is the P security architecture that can protect all IP protocol communication. IPsec is designed for both
IPv4 and IPv6. If its implementation is optional in IPvr, its mandatory in IPv6. All full IPv6 implemantations have to support IPSec.
Multicast not Broadcast
Transmissions addressed simultaneously to more then one system, can be broadcast or multicasts. Broadcast are used when a piece of information needs communicating to everyone on the network or when the sender does not know the exact location of the system it want to cummunicate with. The exact notation of a broadcast address can vary by the operating system, but it is identified with all 1`s as the host section of an IPv4 address. Each broadcast message causes a CPU interupt on a host that receives such message. Multicast improves the efficiency of a network by limiting the broadcast request to smaller number of only
interested nodes. Hence, it provides less CPU interrupts for the hosts on a network segment. in IPv6, the functions previously supported by IPv4 broadcast such as ARP have been redesigned as router discovery and router soliciation request and are handled by IPv6 multicast. Multicast allows IP packets such as a video stream to be sent to multiple destinations at the same time saving network bandwith. IPv6 uses spesific multicast group address for it uses spesific multicast group addresses for its various function. Thus, Pv6 multicast prevents the problems causes by broadcast storms in IPv4 network.
ICMP
For IPv4, the internet control message protocol, is an internet protocol that is used for reporting fault and
information conditions and for diagnostic functions. It provides error correction and other information relevant to IP packet processing. For example, it can let the IP software on one machine inform another machine about an unreachable destination.
source : http://www.6diss.org/
Dynamic Host Control Protocol is a TCP/IP protocol that enables assignment of temporary IP address at host automatically when the host connects to the network. Dynamic allocation makes it possible to share a relatively small number of ip addresses within a relatively large population. But it is stateful, meaning it must store the different IP addresses and the host these use, plus it keep track of the state by sending keepalive mesages. Therefore, true plug and play configuration is difficult.
But DHCP also has substansial benefits, because it can provide hosts not only addresses but also basic network services information, such as the DNS address. In IPv4, DHCPv6 functions largely similiar but adds substansial benefits. In IPV6, autoconfiguration is handled without DHCP. Still, DHCPv6 is needed to learn about other network details such as DNS and SMTP server address.
source : http://www.6diss.org/
Classless interdomain routing is and address scheme that uses aggregation strategies to minimize the size of top-level internet routing tables. Routes are grouped with the objective of minimizing the quantity of information carried by core routers. Them main requirement for this scheme is the use of routing protocols that support it, such as the BGP version 4 and RIP version 2.
CIDR offers the advantages of small routing table, which improves router performance. But while it was good intermediary solution that offered some time to search for a final solution, CIDR couldnt solve the critical growth of the internet. CIDR is no long term solution for the IPV4 address exhausted problem.
source : http://www.6diss.org/
Network Address Translation takes place on the boundary between public and private networks. Hosts inside the private network are assign private addresses, that are not reachable from the internet. NAT is useful when communication is needed between a host in the private network and another host in the internet.
A system, mostly a firewall or router, stores the addresses of the hosts used an intranet or other private network and converts them to publicly accessible host addresses or internet IP addresses. NAT makes it possible to use a large number of devices within the private network without depleting the limited number of available numeric internet IP addresses.
The use of NAT only delays the timeof exhaustion of ipv4 addresses but does not solve the real large-scale growth problem, because IP is now widely adopted as the applications convergence layer for non-computing devices. With ipv4, only the endpoints handle the connection and the underlying layers do not handle any connection. However, when NAT is used, it breaks the end-to-end connection of IP. Furthermore, usage of NAT adds a lot of complexity for the management of certain network services. Moreover it can have a severe performace impact on the translator device NAT also inhibits the implementation of end-to-end network security. Along the path from origin to final destination, any translation of parts of the header, which is protected by some cryptographic functions, will break the integrity check.
Furthermore, NAT requires the network to keep the state of the connections in order to handle the translation of addresses and ports. Therefore, any failure of the NAT device or links near the NAT device will make fast rerouting difficult. Additionally, every new deployment of non-NAT-friendly application will require upgrading of the NAT device.
Finnaly, different networks can use the same private address spaces. When they are combined, connected or merged, an address space collision wil result. And though the ratio of internal/reachable to external addresses mapping must be large to make NAT effective, NAT is not quite as useful if the number of inside servers is large.
source :http://www.6diss.org/
Its very easy to reset windows xp password without using any 3rd party programs. I have tried it for windows xp sp1 and sp2, and it works. To reset the forgotten password, put your windows xp cd installer then repair your windows. When you see installing devices screen the press SHIFT + F10 (windows setup will interupting for a while) then you will see command prompt windows and type NUSRMGR.CPL (for opening user account management view). From here you can reset an administrator password and other user password.
Have a nice try.
- Accessibility Controls - access.cpl
- Accessibility Wizard - accwiz
- Add Hardware Wizard - hdwwiz.cpl
- Add/Remove Programs - appwiz.cpl
- Administrative Tools - control admintools
- Automatic Updates - wuaucpl.cpl
- Bluetooth Transfer Wizard - fsquirt
- Calculator - calc
- Certificate Manager - certmgr.msc
- Character Map - charmap
- Check Disk Utility - chkdsk
- Clipboard Viewer - clipbrd
- Command Prompt - cmd
- Component Services - dcomcnfg
- Computer Management - compmgmt.msc
- Control Panel - control
- Date and Time Properties - timedate.cpl
- DDE Shares - ddeshare
- Device Manager - devmgmt.msc
- Direct X Troubleshooter - dxdiag
- Disk Cleanup Utility - cleanmgr
- Disk Defragment - dfrg.msc
- Disk Management - diskmgmt.msc
- Disk Partition Manager - diskpart
- Display Properties - control desktop
- Display Properties - desk.cpl
- Dr. Watson System Troubleshooting Utility - drwtsn32
- Driver Verifier Utility - verifier
- Event Viewer - eventvwr.msc
- Files and Settings Transfer Tool - migwiz
- File Signature Verification Tool - sigverif
- Findfast - findfast.cpl
- Firefox - firefox
- Folders Properties - control folders
- Fonts - control fonts
- Fonts Folder - fonts
- Free Cell Card Game - freecell
- Game Controllers - joy.cpl
- Group Policy Editor (for xp professional) - gpedit.msc
- Hearts Card Game - mshearts
- Help and Support - helpctr
- HyperTerminal - hypertrm
- Iexpress Wizard - iexpress
- Indexing Service - ciadv.msc
- Internet Connection Wizard - icwconn1
- Internet Explorer - iexplore
- Internet Properties - inetcpl.cpl
- Keyboard Properties - control keyboard
- Local Security Settings - secpol.msc
- Local Users and Groups - lusrmgr.msc
- Logs You Out Of Windows - logoff
- Malicious Software Removal Tool - mrt
- Microsoft Chat - winchat
- Microsoft Movie Maker - moviemk
- Microsoft Paint - mspaint
- Microsoft Syncronization Tool - mobsync
- Minesweeper Game - winmine
- Mouse Properties - control mouse
- Mouse Properties - main.cpl
- Netmeeting - conf
- Network Connections - control netconnections
- Network Connections - ncpa.cpl
- Network Setup Wizard - netsetup.cpl
- Notepad notepad
- Object Packager - packager
- ODBC Data Source Administrator - odbccp32.cpl
- On Screen Keyboard - osk
- Outlook Express - msimn
- Paint - pbrush
- Password Properties - password.cpl
- Performance Monitor - perfmon.msc
- Performance Monitor - perfmon
- Phone and Modem Options - telephon.cpl
- Phone Dialer - dialer
- Pinball Game - pinball
- Power Configuration - powercfg.cpl
- Printers and Faxes - control printers
- Printers Folder - printers
- Regional Settings - intl.cpl
- Registry Editor - regedit
- Registry Editor - regedit32
- Remote Access Phonebook - rasphone
- Remote Desktop - mstsc
- Removable Storage - ntmsmgr.msc
- Removable Storage Operator Requests - ntmsoprq.msc
- Resultant Set of Policy (for xp professional) - rsop.msc
- Scanners and Cameras - sticpl.cpl
- Scheduled Tasks - control schedtasks
- Security Center - wscui.cpl
- Services - services.msc
- Shared Folders - fsmgmt.msc
- Shuts Down Windows - shutdown
- Sounds and Audio - mmsys.cpl
- Spider Solitare Card Game - spider
- SQL Client Configuration - cliconfg
- System Configuration Editor - sysedit
- System Configuration Utility - msconfig
- System Information - msinfo32
- System Properties - sysdm.cpl
- Task Manager - taskmgr
- TCP Tester - tcptest
- Telnet Client - telnet
- User Account Management - nusrmgr.cpl
- Utility Manager - utilman
- Windows Address Book - wab
- Windows Address Book Import Utility - wabmig
- Windows Explorer - explorer
- Windows Firewall - firewall.cpl
- Windows Magnifier - magnify
- Windows Management Infrastructure - wmimgmt.msc
- Windows Media Player - wmplayer
- Windows Messenger - msmsgs
- Windows System Security Tool - syskey
- Windows Update Launches - wupdmgr
- Windows Version - winver
- Windows XP Tour Wizard - tourstart
- Wordpad - write
| Hosts | Netmask | Amount of a Class C | |
|---|---|---|---|
| /30 | 4 | 255.255.255.252 | 1/64 |
| /29 | 8 | 255.255.255.248 | 1/32 |
| /28 | 16 | 255.255.255.240 | 1/16 |
| /27 | 32 | 255.255.255.224 | 1/8 |
| /26 | 64 | 255.255.255.192 | 1/4 |
| /24 | 256 | 255.255.255.0 | 1 |
| /23 | 512 | 255.255.254.0 | 2 |
| /22 | 1024 | 255.255.252.0 | 4 |
| /21 | 2048 | 255.255.248.0 | 8 |
| /20 | 4096 | 255.255.240.0 | 16 |
| /19 | 8192 | 255.255.224.0 | 32 |
| /18 | 16384 | 255.255.192.0 | 64 |
| /17 | 32768 | 255.255.128.0 | 128 |
| /16 | 65536 | 255.255.0.0 | 256 |
/25 — 2 Subnets — 126 Hosts/Subnet
|
/30 — 64 Subnets — 2 Hosts/Subnet
|
||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
/26 — 4 Subnets — 62 Hosts/Subnet
|
|||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
/27 — 8 Subnets — 30 Hosts/Subnet
|
|||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
/28 — 16 Subnets — 14 Hosts/Subnet
|
|||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
/29 — 32 Subnets — 6 Hosts/Subnet
|
