Archive for the ‘Windows’ Category

Do subnet math in your head

April 12th, 2007

Subnets are a necessary part of networking and while there are a lot of websites with charts out there. You can print out one of many such charts really small, then laminate it, or better, use our God-given noggen and memorize it! We learned multiplication tables as a kid – learning subnetting is about as easy you work with me on this… Take 20 minutes now and you’ll know this for life.

At first, subnets were hard for me to understand – until my brother Hans somegeek explained it in a really simple way.

Definition
A subnet is a portion of the full net – and every network we use is part of a subnet. As geeks we mostly deal with class C or smaller.

Lets work with an example. You just started working at RARPAnet and have lots of computers to set up. You were assigned the entire 10.0.0.0 network for address space. Since the 10 network is designated for use on private networks (its not routed on the public internet) you have lots of addresses.

Class – amount of address space you have:
Class A: The entire 10 network – any address where the first number is the same
Class B: The 10.1, or the 10.2 network – up to the 10.255 network – any address where the first 2 numbers are the same
Class C: 10.0.1, or 10.0.2, up to the 10.0.255 network – any address where the first 3 numbers are the same

Examples of subnets from the 10 network:
Class A: 10.0.0.0 to 10.255.255.255
Class B: 10.1.0.0 to 10.1.255.255
Class C: 10.1.0.0 to 10.1.0.255

Every Subnet has 4 parts to it:

  1. Network – this is the first address on the network – designates the starting address
  2. Hosts – addresses that can be used for hosts (routers, computers, etc)
  3. Broadcast – the last address of the network – for ‘yelling’ at everyone at the same time.
  4. Netmask – used to get the network – put as a mask over the address

Example 1: Break down the 192.168.1 network

For the 192.168.1 subnet:
192.168.1.0 network
192.168.1.1 - 254 hosts
192.168.1.255 broadcast
255.255.255.0 netmask

Every IP address is made up of 32 bits in 4 chunks of 8 bits.

To count in binary is really simple – use the table below to make the number – a sum of its parts.

Basic table for counting up to 255 in binary: first row of 1′s, second row powers of 2 starting with 1:

1      1     1     1     1    1    1    1
128   64    32    16     8    4    2    1

Conversion of regular numbers to binary:

1 in binary:

1      1     1     1     1    1    1    1
128   64    32    16     8    4    2    1
                                        1

2 in binary: 2 + 0

1      1     1     1     1    1    1    1
128   64    32    16     8    4    2    1
                                   2    0 = 2
                                   1    0

5 binary: 4 + 1

1      1     1     1     1    1    1    1
128   64    32    16     8    4    2    1
                              4    0    1 = 5
                              1    0    1

18 binary: 16 + 2

1      1     1     1     1    1    1    1
128   64    32    16     8    4    2    1
                  16     0    0    2    0 = 18
                   1     0    0    1    0

187 in binary: 128 + 32 + 16 + 8 + 2 + 1

1      1     1     1     1    1    1    1
128   64    32    16     8    4    2    1
128    0    32    16     8    0    2    1 = 187 
1      0     1     1     1    0    1    1 

Convert Binary to Decimal
Convert 10110 to a decimal number:

First 10110 is 5 bits, you biggest number in the count set will always be 2^(n-1). 
Another way to remember is the largest number will be half of 2^n;
2^5 = 32; half is 16.

The mathematical way is:
n = 5; so 2^(5-1) = 16 That’s your biggest number, so count set is “16 8 4 2 1″

1*16 + 0*8 + 1*4 + 1*2 + 0*1 = 22 – convert 22 back to binary above – it can be done in your head.
Takes some practice but like counting change when working a cash register, it’ll flow after a while.

With the binary-decimal conversion understood, lets look at IP’s – v4 that is. The binary for the full IPv4 address is: 1111111.1111111.1111111.1111111

Detailed breakdown

Now, for a host with ip of 192.168.1.12, the IP and subnet are often denoted together in one of two ways:
192.168.1.12 255.255.255.0
or more often used and shorter to write:
192.168.1.12/24

The /24 means of the 32 bits for the address, use first 24 bit to denote the network, last 8 bits for address space:

For a /24: There 8 bits for address space:
Subtract the slash number from 32: in the case of /24:
32 – 24 = 8 bits;
Then the number of IP addresses used is 2^8bits = 256;

256 addresses: first address is network, last is broadcast; 254 in the middle are for hosts.
192.168.1.0 network
192.168.1.1 to 192.168.0.254 hosts
192.168.1.255 broadcast
255.255.255.0 subnet mask
1111111.1111111.1111111.00000000 Last 8 bits are zero's

How to easily remember this:
Mentally I think this: I see 192.168.1/24 – then
1. an IP address has 32 bits for address
2. 32 – 24 = 8; 2^8 = 256;
3. 256 addresses – first one is network; last one is broadcast, the rest in the middle are hosts.

Example: You are given an address of 192.168.1.16/29 for your network:
For a /29: There are 3 bits for address space:
1. 32 bits – 29 bits = 3 bits for address space;
2. 2^3 = 8 – the number of addresses in this network
3. Since my first address is 192.168.1.16, 192.168.1.23 is my last address

Summary:
8 addresses: First is network, 6 in the middle for hosts, last is the broadcast address:

192.168.1.16                       network
192.168.1.17 to 192.168.1.22       hosts
192.168.1.23                       broadcast
255.255.255.248                    subnet mask     

1111111.1111111.1111111.1111000  Last 3 bits are zero's

… and since this subnet is most like subdivided into groups of 8 ip’s, there is a new network every 8 IP addreses on this 192.168.1 subnet – a good way to segment a network for security, etc.

192.168.1.0-7
192.168.1.8-15
192.168.1.16-23               (your network)
192.168.1.24-31
192.168.1.32-39
...and so on up to
192.168.1.248-255

So there it is – binary math, subnets and now no chart to carry in your pocket. This website has a subnet calculator – good for refence and checking your work.

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Configure Microsoft Outlook for access from home, work, Treo and a laptop

February 21st, 2007

Microsoft outlook is widely used and though it has some caveats, works well with Treo’s and Blackberry’s.

This tutorial will detail the set-up I use with my email and I believe works well. I access and send email from 3 different computers (desktop at home+work, laptop, + Treo 600). The standard Outlook configuration had to be tweaked – and thus this tutorial. Some may have a better way to configure all this – feel free to comment below.

1. Decide on which computer will be the “main” computer. I work primarily as a loan officer, so leaving sensitive docs on an email server for months scares me (as is the case with IMAP).

The main computer:

  • Has Outlook 2000/2003/Latest version installed and working
  • Most emails are sent from this computer.
  • Saved emails are on this computer
  • This is the only computer that can delete emails from my inbox – more on this later.

Once you have chosen the main computer, the rest (including your Treo/Blackberry) will be configured as “client” computers.

2. The other computers, AKA “clients” will be configured to read and send email, but not delete. Its best to have one computer that can do any deletions, this ensures an email is not accidentally deleted or stuck on another computer.

3. Main computer configuration:

  1. Outlook: Tools – E-mail Accounts – Add new email account

  2. Account type: select POP3

    New email account

  3. Enter your account information. The login will be your complete email address, and password is CaSe seNSiTiVe.

    Select server type

  4. Configure your outgoing mail server – if you are on SBC/AT&T DSL, you must use their email server to send email.

    Configure outgoing mail server

  5. This part is what makes the difference – in the “delivery section”, set the radio buttons as shown. This will keep messages on the server until they are deleted or moved to another folder besides “inbox” in Outlook.

    Configure outgoing mail server


4. Client computers – including hand-helds.

There are two methods of retreiving email: POP3 and IMAP.

POP3: Connect, download new messages from the mail server to the computer, then delete the copy on the server (typical setup), then disconnect – do this every 15 minutes or so ” This is old and established way to do email. It is what allows for people to read messages offline since copies of the entire message were downloaded.


IMAP:
Connect and stay connected, get message subject list from the server every few minutes, only view entire message and attachments when its read. Nothing is really downloaded – the message and other email boxes typically stay on the server – like browsing the internet except its your email. Must be connected to read any email. All messages are kept on the server – easier cause its only one inbox to deal with.

These will be configured for either POP3 or IMAP. POP3 settings are the same as above in step 4 except leave the checkbox “remove messages from server when deleted from “deleted items” un-checked.

To configure for IMAP:

  1. Outlook: Tools – E-mail Accounts – Add new email account

  2. Account type: select IMAP

    Select IMAP

  3. Fill in email information – note login is complete email address, and password is CaSe seNSiTiVe

    Select IMAP

  4. in More settings – Advanced tab – not much here, but here it is.

    More settings - IMAP


Follow the IMAP or POP3 set-up for each client. Configuration for Thunderbird, Eudora, Treo email, and other mail programs is similar and here’s what is now set-up:

  • The main computer: check all email and leave a copy on the server
  • The main computer can filter spam and delete messages. When the “deleted items” in Outlook folder is emptied, those emails are removed from the server.
  • Clients and Treo’s – can check and send email, since all mail remains on the server, it can be accessed.
  • If traveling, the messages remain in the inbox, and there is a copy on the main computer (if it was left running). Later, at home boot the main computer, Outlook will upload all messages, and they can be sorted from there. No messages lost – or has happended to me – having the only copy of a message with an attachment stuck on a Treo 600 that can’t send attachments. :(

I have used this set-up for a year and it’s worked well to keep in contact and for a little more work to set-up, saved a lot of trips to the office just to read email.

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Add remove programs broken

November 18th, 2006

Re: Re: I can’t open add/remove programs!!!!!!!!!!!!!!!

I ran into the same problem, and none of the recommended solutions worked. Finally I found the answer.

This is taken from MS Knowledge Base Article Q266668 which can be found at http://support.microsoft.com/kb/q266668/

I did not bother with steps 1-4 (checking registry entries).

The following command fixed it:

Follow the steps in one of the following procedures, as it applies to your computer, and then test to determine if this issue is resolved.

If the issue is resolved, skip the remaining steps.

If the issue is not resolved, go to step 5.

To resolve this issue with Internet Explorer 6.0 installed, repair Internet Explorer 6.0:

a. Click Start, and then click Run.

b. Paste the following command in the Open box, and then click OK:

rundll32 setupwbv.dll,IE6Maintenance “C:Program FilesInternet ExplorerSetupSETUP.EXE” /g “C:WINDOWSIE Uninstall Log.Txt

Because this command is case sensitive, Microsoft recommends that you copy the command from this article, and then paste the command in the Open box.

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Useful windows networking commands

November 10th, 2006

Show TCP ports in use and by what program, use UDP for UDP ports

 netstat -naop TCP

Show the ip, netmask and gateway for a PC

ipconfig 

Clear networking cache – if “Repair” is not clearing the cache

netsh interface ip delete arpcache
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Scan in a document & convert text with OCR

October 11th, 2006

OCR – optical character recognition is what we do when we read – shapes represent letters.

This write-up shows how to quickly scan in documents for either archiving (keep a scan of the page, recycle the paper copy), email by pdf, or for editing a document without typing it all in. I do work as a mortage loan officer and sometimes its better to send a pdf than a fax – especially if the document is barely readable. I also tend to keep everything until the loan is closed – keep clutter (fax cover sheets, etc) and if I need something later, it’s there. More than once I have shredded something I needed a phone number off or something like that. Also, it saves the space in the file drawers for important files. » More: Scan in a document & convert text with OCR

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