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Home Network Setup

Posted by Rick on in Hardware, Technology How To's, Unix, Windows 0 Comment

Home Network Setup

Originally Posted 11/20/2000. Ironically a lot of this is still useful.

 

Home Networking

 

 

            In the day and age of Multi-computer families, a frequent argument is, who gets to be online? The answer is simple, Modem Sharing or networking. Modem Sharing can be done one of several ways, using a regular Analog Modem (300 baud to 56.6K,) DSL or ADSL, ISDN and Cable modems. You could also be on a T-1 (or greater!) network connection, but then why are you reading this? J

           

 

Which one is right for me?

 

            Analog Modems

 

            Pros: Can be used anywhere a telephone is located.

            Cons: Limited to an upper bandwidth of 53K due to telephone regulations in the US. May be slightly higher in other countries. Modems also suffer greatly from phone line quality, crosstalk (where two or more wires touch each other in the wrong place therefore mixing the signal,) and any line noise at all. More then two low-bandwidth applications can easily make this almost worse then nothing. Ties up the phone line if you only have one.

 

            ISDN:

            Pros: Very fast, two 64K channels giving 128K total. Even one channel at 64K is cleaner and noticeably faster then 56k.

            Cons: Still only 128K, costs the same as DSL. In addition, totally against ISDN specs, some companies charge you for the 2nd line to automatically drop when an incoming or outgoing phone call is detected, so your phone is still tied up.

 

            ADSL/DSL:

 

            Pros: Very fast… minimum 265K maximum 7 megabits, makes this very, very fast. Phone lines do not get tied up at all. Can easily support multiple high-bandwidth applications (web browsers, games, large downloads, etc.) Can get a Static IP, which is very useful if you wish to run servers at home.

            Cons: Suffers slightly at the phone companies end due to misconfiguration. Such things as dropped carriers, being able to see other people’s computers (in Network Neighborhood.) and depending on the carrier, a slight slow down in bandwidth due to the phone company over selling it. Remember, at this point the phone company does not have to guarantee a certain amount of bandwidth… you simply have speeds up what ever your limit is.

 

            Cable:

 

            Pros: As above, very, very fast

            Cons: Suffers greatly from overselling of bandwidth. If other cable subscribers are all using it at the same time as you, they effect your speed. If you’re the only one in the area then it’s not a big deal. But frequently this slows down to speeds that are little better then a regular modem. Can’t get a Static IP number,  you’ll never be able to run a server, at least not very effectively.

 

Initial Setup

 

            First you need to get the network equipment. Your best bet for ease of configuration and portability is to get a couple of  mid-priced range network cards, (Kingston is a good bet) and a decent 100Base hub. (NetGear, Bay Networks, Intel.) You can buy cheaper cards such as SMC but they will effect your speed. If you can afford it, a switch is even better, giving you more bandwidth and speed. You’ll also want several lengths of networking cables too. J

            Second, your modem or router should be hooked up to one of the computers. In the case of some DSL routers, these can be directly hooked up to your hub. Other products have a DSL router and hub built in to the same unit. In my opinion this is unncessecary and could cause problems down the road. Remember to install the 2nd network card if it’s an external unit. (Cable and DSL only.)

            The third step is to setup the modem/router itself to connect to the network. This changes from different brands of Cable modems and routers. If you’re using a regular 56k modem, connect as you usually would.

            The last step is to make sure you know what your IP Address, DHCP Server (if needed,) DNS Server, Gateway and Netmask numbers are. You may or many not have all of these options. These have four numbers or “octets” like 255.255.255.0 or 192.168.1.0 Each of these numbers or octets can be anything between 0 to 255, with some exceptions.

            Your network should look something like this when you’re done:

            ISP -> Modem/Routers -> Computer -> Hub <-> Other computers

            One thing to point out, the computer plugged into the modem/router needs to be running an Operating system capable of doing routing. Windows 95 is not capable of doing this.  Windows 98 sorta does it, while Windows NT, ME, 2000, FreeBSD and Linux are all capable of doing so. Mac OS X being based off of FreeBSD can also do this. Windows 95 is capable of doing so with the help of a third party commercial piece of software. I personally run FreeBSD on  a 486 SX-25, recently upgraded to a Intel P-166 to do this. (BTW, it runs quicker and more efficiently then Windows NT or 2000 on a AMD –450 with 128 megs of RAM!)

 

Network Setup

 

            The Network hardware is pretty straightforward. One cable from each computer plugs into the hub or the switch. Each port should have a LED saying the port is active. Usually there is a 2nd LED that shows network traffic on that port of the hub.

            Start with the computer connected to the modem/router. The protocol that you wish to run is TCP/IP, make sure IPX/SPX and Netbui are both disabled unless you need them. Most games these days don’t care what protocol you’re running, but some of the older ones need IPX/SPX (Duke Nukem 3D, Warcraft, early Diablo releases, etc.) Having Netbui disabled helps keep people from hacking into your computer, there are hundreds of security holes in Windows with this protocol.

            After adding TCP/IP in the Network option under Control Panel Add in your network settings as provided by your ISP. Usually your ISP gives you instructions on how to do this, you’ll want to follow them. Test your dial-up and networking. The computer should run perfect.

            Now comes the tricky part, configuring the other computers. The easiest configuration is the dual network card and external modem/router option. The first NIC connected to the modem/router is configured exactly as it should be. The 2nd NIC’s TCP/IP Address should be one that is assigned by you. For ease you should pick something like 192.168.1.1 You can pick any number, but make sure the first three octets are all the same. Do not pick the same first three octets as the IP assigned to your 1st NIC… it will cause problems.

            Your Netmask is always 255.255.255.0 do not ever change this unless you know what you’re doing, your network will become unreachable. The Gateway address is the same as the IP address of the 1st network card. Keep in mind this is only for this card. Certain operating system will not accept this option either, but most Windows systems should.

            In addition some operating systems will need a flag set to make it a gateway or router machine. For instance, in FreeBSD and Mac OS X /etc/rc.conf needs the line “gateway=enable” This also invokes the NAT or “Name Address Translation” program. NT and 2000 should both give you a similar option.

            The 2nd (and all subsequent computers) will have an IP address of 192.168.1.x (where x is any number between 2 and 254, do not use 1 as it’s already used, 0 and 255 should also be reserved, Just in case.) Their Gateway address will be the IP of the 2nd network card in the first computer! DNS or Name Server address will be the same across all computers, unless you setup a nameserver, which for a small network I recommend against doing.

            For computer with a single network card, and a modem, the theory is the same. Use the gateway to be the IP number of the modem/router. Remember that IP numbers are assigned to Network interfaces, not to the computer. A computer can theoretically have an infinite amount of IP addresses, in reality it’s whatever number the operating system is capable of handling, at least 254 though, and more then most people will ever need.

            If you have a large amount of computers, say more then 5 or 6, you may want to look into assigning these IP numbers via DHCP, it’s initial setup is harder, but more robust with large networks, it also makes the client machines virtually Plug and Play.

 

            Security

           

            Now that your network is running, it’s time to turn your eye towards security. The best way is a firewall. Windows NT, 2000, FreeBSD and Linux can all do this. Linux has more security holes fixed then Windows NT or 2000, and FreeBSD even more. If you’re really serious about security and wish to really learn, OpenBSD is the best of all. FreeBSD offers the best choice of security and ease of setup.

            A Firewall is simply that, it keeps the bad stuff from coming in, and if you wish, keeps stuff from going out. It works by stopping or dropping traffic if it does not adhere to the rules that you define.

            The first step in building effective firewalls is to block everything. Then step by step you want to unblock stuff you want. Port 80 (http requests,) 21 and 22 (FTP) are good starts. Some programs will want other ports open, PCAnywhere needs 186 & 187 open. Remember, it’s easier to block stuff before it’s broken, then to block if after somebody has hacked into your computer.

 

            Conclusion

 

            These are really some very basic instructions. Unluckily due to the sheer amount of different configurations out there, I can’t give step by step instructions like I’d like too. If you have specific questions though, post to the Hardware and Software forums and somebody can help! J Even then you should have a working network configuration in no time at all!

How To: Reset Admin/Root Password

Posted by Rick on in Hacking, Microsoft, Technology How To's 25 Comments

How To: Reset Admin/Root Password

Anyone who has been in the IT business for any length of time knows literally hundreds of passwords. As we get older though it becomes harder and harder to remember each password and continue with safe security practices. Many companies have gone to centralized password systems. But such software is not always compatible with every OS there is. In such cases as the four year old FreeBSD server sitting in the corner that serves one application. So, here is a large list on ways to reset the root password or administrative user on many operating systems. Keep in mind that these instructions all assume you have physical access to the server in question.

FreeBSD (all versions)

  1. Turn Server off. Hitting the Power Button should start a shutdown cycle.
  2. Hit ESC when the OS starts booting
  3. Choose option 4 to boot into Single User Mode
  4. When asked for a shell, hit enter to default to /bin/sh
  5. Once the machine is booted and you see the hash, type
    1. mount -u /
    2. mount -a
  6. Type passwd to reset the password
  7. Enter new password and confirm it. “pam_chauthok(): error in service module” means that the filesystem is not mounted. Follow step 5 again.
  8. Type reboot or hit the power button again to reboot the machine normally.

Linux (Lilo Loader)

  1. Reboot machine
  2. Hit Esc to get to boot prompt if it doesn’t to it automatically
  3. type: linux single
  4. type: passwd
  5. Enter in and confirm new password
  6. type: sync
  7. type: reboot

Linux (GRUB loader)

  1. Reboot machine
  2. Hit Esc to get to boot prompt if it doesn’t to it automatically
  3. Select the Kernal. Hopefully there is only one or two and the names are descriptive. But any one SHOULD work.
  4. type: e
  5. Select the line that starts with “Kernal”
  6. type: e (again)
  7. Add the letter s (in lower case) to the very end of the line
  8. Hit Enter
  9. type the letter b to start booting
  10. Mount the drives type:
    1. mount -t proc proc /proc
    2. mount -o remount,rw /
  11. type: passwd
  12. Enter in new password and confirm it
  13. type: sync
  14. type: reboot

OS X (All Versions) OS X has two ways to reset the Administrator Password.

Option 1:

  1. Find the computer’s original boot disc. These are system specific. If it’s not available, any OS X retail boot disk will work. The wrong disc will give an error message.
  2. Boot off the disc. Accomplish by holding down the c key during power up.
  3. At the Menu go to: Utilities
  4. Choose “Reset Password”
  5. Enter in new password and confirm
  6. Click on Installer
  7. Choose Quit

Option 2:

  1. Hold Down Apple+S while booting computer
  2. Type: sh /etc/rc
  3. Type: passwd root (if that doesn’t work try admin or administrator instead of root)
  4. Enter in new password and confirm
  5. Type: reboot

Solaris (On Sun Hardware)

You must have the Solaris CDRom to do this. If you do not have physical media, get it here. Note that this download is for Ver10, so may not work on older versions.

  1. Reboot Machine
  2. Hit Stop +A to get to the OK prompt
  3. Type: boot cdrom -s
  4. Once booted off the CDRom, type: mount /dev/disk/c0t0d0s0 /a (those are Zeros)
  5. Type: vi /a/etc/shadow
  6. Use the h,j,k,l keys to move around in vi (or go here for more commands)
  7. On the second line, which says root:<bunch of random letters/numbers> type: dd
  8. Type: :wq! to save and quit out of vi
  9. Type: umount /a
  10. Type: boot ok -s (to boot into single user mode)
  11. Type: passwd
  12. Enter in new password and confirm it
  13. Type: reboot

Note that many Solaris systems may have mirrored volumes, a volume manager or other method of copying the full filesystem. If this is the case these instructions will need to be followed for both volumes, otherwise corruption can easily occur.

Solaris (i386/Intel Hardware)

Again you should have the CDRomto boot off of.

  1. Reboot Computer
  2. Enter Bios and Change Boot Order to CDRom first if needed
  3. Boot Computer
  4. On Boot Menu choose Single User mode, which is Option 6 on Solaris 10
  5. Choose Yes when asked to mount the root filesystem
    1. If you choose “No” it can still be mounted with the same command, /dev/disk/c0t0d0s0 /a (those are Zeros)
  6. Type: vi /a/etc/shadow
  7. Use the h,j,k,l keys to move around in vi (or go here for more commands)
  8. On the second line, which says root:<bunch of random letters/numbers> type: dd (to delete whole line)
  9. Type: :wq! to save and quit out of vi
  10. Typ: cd /
  11. Type: umount /a
  12. Type: init s
  13. At password prompt hit enter key
  14. Type: passwd root
  15. Enter in new password and confirm it
  16. Type: reboot

General Windows

Amazingly Windows Server does not have an easy way to recover the password. Microsoft would call this security, but do provide a package of recovery software that does the job. But it costs $199. Tech Trax has an article on reseting the password on XP system via the XP install disc. Or you can download an emergency boot cd from here, here, or buy a password cracker from here. Be extremely careful with downloading Windows password crackers from the Internet. Yes they may work, but it’s more likely they are actually a Virus or a Trojan and could cause more problems then you have already.

*edit* Hiren’s BootCD has several utilities that will allow the reseting of Windows passwords.

Windows 7
This does not reset the password, but allows you to make a new Administrative user who can then change the password in the control panel for the other user.

  1. Boot off your Windows 7 DVD
  2. Choose “Repair your computer”
  3. Go to the recovery environment
  4. Open command prompt
  5. Type “cd windowssystem32”
  6. Type “Rename Utilman.exe Utilman.exe.bak”
  7. Type Copy cmd.exe Utilman.exe
  8. Reboot Computer
  9. At Login Screen, hold down the Windows and “U” keys
  10. Type net user /add NewAccount mypassword (use your own name for NewAccount)
  11. Type net localgroup administrators NewAccount /add (replace NewAccount with the name used above
  12. Login with new user
  13. Go to Start -> Control Panel -> User Accounts and Family Safety
  14. Click on User Accounts
  15. At the bottom of “Make changes to your user account area” click “Manage another account”
  16. Choose old user
  17. Click “Change Password”
  18. Enter the new password
  19. Logout of the current account
  20. Login to the old account with the new password

Windows 8
User the Microsoft Diagnostic and Recovery Tools (download here) to reset the password.