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Computer Network – RJ45 Connectors

RJ45 Crimped
RJ45 Crimped

RJ-45 connectors

RJ45 is a type of registered jack. The registered jack specifies the physical male and female connectors as well as the pin assignments. RJ45 features 8 pins and is the standard connector for Ethernet based networks. We can also find it on ISDN, and T1 connections. Ethernet is the standard media for the VOIP phones so we can find it used with modern digital phone systems. The RJ11 male connector, (standard telephone connector), fits perfectly into an RJ45 female connector being a little narrower, which is why many companies have deployed data networks only. The middle pair only is used for the telephone connection. There are different RJ45 male connectors for various cables.

  The male RJ45 are very cheap but they are prone to various problems.
Shielded RJ45
Shielded RJ45
The locking tab is prone to breaking. Here are some tricks to avoid this: buy the connectors with the locking tab curved down so it avoids the snagging. If you can’t find the cleverly designed connectors use boots to avoid snapping the tabs.
Snagless RJ45
Snagless RJ45

Snagless RJ45
Snagless RJ45

Snagless RJ45
Snagless RJ45

Snagless Shielded RJ45 Male
Snagless RJ45 Sheilded

There are RJ45 specially designed for solid cable, for stranded cable, for STP cable.
Rj45 Male Compare Rj45 Male Compare Use only the appropriate connector for the cable you install. Using an RJ45 for solid wire with stranded wires, or the other way around, will cause poor contacts, hence a bad connection.
Use a good quality crimper that doesn’t press on the tab when you crimp the connector.
Crimping a male RJ45 is not easy. The operation requires dexterity attention and training. If you want to make your life easier, you can use wire guides that come with some packages. Practice a lot and you won’t need the guides.
Check the “How to make a patch cord” post, for a detailed, step by step article with pictures. (coming soon)

How to Install Squid with Active Directory Authentication on Debian

How to Install Squid with Active Directory Authentication on Debian

Squid is a caching proxy software, licensed under GNU GPL, (free software).
It can help your Organization to reduce bandwidth and improves response times by caching and reusing frequently-requested web pages.
Squid has extensive access controls and if you don’t mind Command Line Interface is not too hard to configure. It runs on most available operating systems including Windows.
The following article is a step by step HOW TO Install Squid on Debian. Most of the steps are easily applicable to any other Linux distribution such as: RedHat, Suse, Ubuntu, etc…

Hardware requirements

Choose the machine wisely – if you are running a 50 computers Network a PIII should be enough provided that all you do is Web Caching and Filtering.
The memory is the most important and after that the disk speed. If you plan your proxy for a bigger Network you should consider using SCSI drives or SAS, and a faster CPU.
Memory requirements are explained later in the document.

Package Installation

Instal Debian minimal. The install cd, (only 650Mb) should be enough for this.
Reboot after installing and add packages with Aptitude (grafical interface) or "apt-get install program".
Add the following packages:
Kerberos apt-get install krb5-{admin-server,kdc}
PAM apt-get install libpam0g-dev
Apache if you want proxy Auto-Configuration apt-get install apache2
Dansguardian if you need advanced WEB filtering
SARG if you want a log analyzer for your WEB access/filter

– – – – – – – – – – – – – – – – – – – – – –

Configure Samba

Samba is going to be used for authentication.
Note that if you run squid in transparent mode the authentication will not work.

#nano -w /etc/samba/smb.conf

Add or remove daemons to autostart
#update-rc.d  winbind defaults
#update-rc.d  samba defaults

– – – – – – – – – – – – – – – – – – – – – –
netbios name = proxy
workgroup = SUBDOMAIN
security = ADS
password server = server1.subdomain.domain.root server2.subdomain.domain.root
socket options = TCP_NODELAY SO_RCVBUF=8192 SO_SNDBUF=8192
idmap uid = 10000-20000
domain master = no
local master = no
preferred master = no
winbind enum groups = yes
winbind enum users = yes
winbind uid = 10000-20000
winbind gid = 10000-20000
winbind separator = +
winbind use default domain = Yes
encrypt passwords = yes
log level = 5 passdb:5 auth:10 winbind:5
server string = proxy
dns proxy = no
log file = /var/log/samba/log.%m
max log size = 1000
syslog only = no
syslog = 0
encrypt passwords = true
load printers = no

– – – – – – – – – – – – – – – – – – – – – –
Do not add other parameters to the configuration file as they are not needed.
You can always tweak your configuration file later on if you need additional tweaking. If you do need further modifications do one at a time and test it extensively before release to production.
After editing smb.conf run the following command
# testparm
This will test your samba configuration file against any errors.
If there are no errors restart samba:
proxy:~# /etc/init.d/samba restart
proxy:~# /etc/init.d/winbind start
– – – – – – – – – – – – – – – – – – – – – –
Add the server to the domain
#net ads join "Ottawa Computers/Servers" -U Administrator -S server1.sub-domain.domain.edu
If you have Windows 7 you might get this in your /var/log/samba/log.wb: "NTLM CRAP authentication for user returned NT_STATUS_INVALID_PARAM"
If you get it follow the instructions below to tell Windows to use NTLM version1. Note that this is a security downgrade and it opens the door for an SMB man-in-the-middle attack. Asses the risks and the advantages before you do the change.

Run local GP on W7 gpedit.msc and look for:
Local Policies Security Options Network security: LAN Manager authentication level
Change from "Not Defined" to "LM & NTLM – Use NTLMv2 session if negotiated"
– – – – – – – – – – – – – – – – – – – – – –

Configure Squid

Make a backup copy of the default configuration file:
# cp /etc/squid/squid.conf /etc/squid/squid.conf.original
Edit the file squid.conf:
#nano –w /etc/squid/squid.conf
Replace everything in the file with the below text:

– – – – – – – – – – – – – – – – – – – – – –

#Proxy configurationuration - /etc/squid.squid.conf

# -----------------------------------------------------------------------------
auth_param ntlm program /usr/bin/ntlm_auth --helper-protocol=squid-2.5-ntlmssp
auth_param ntlm children 30
auth_param basic program /usr/bin/ntlm_auth --helper-protocol=squid-2.5-basic
auth_param basic children 5
auth_param basic realm Squid Proxy Server
auth_param basic credentialsttl 2 hours
acl authenticated_users proxy_auth REQUIRED
http_access allow authenticated_users
auth_param ntlm keep_alive on

# -----------------------------------------------------------------------------
#Deafult acl’s
acl all src all
acl manager proto cache_object
acl localhost src
acl to_localhost dst

#Declare your local network and any additional subnets
acl localnet src                # RFC1918 possible internal network
#acl remotesite src

#You would like that some of the users to be excluded from the logging.
###acl bosses src
###log_access deny bosses

#Tell Squid to not log google.ca
#Define the acl for google using regex
acl google url_regex ^http://www.google.ca
#Deny logging the acl
log_access deny google

#Allow the access for your localnet.
http_access allow localnet
#http_access allow remotesite

#Define allowed ports
acl SSL_ports port 443                    # https
acl SSL_ports port 563                    # snews
acl SSL_ports port 873                    # rsync
acl Safe_ports port 80                    # http
acl Safe_ports port 21                    # ftp
acl Safe_ports port 443                  # https
acl Safe_ports port 70                    # gopher
acl Safe_ports port 210                  # wais
acl Safe_ports port 1025-65535  # unregistered ports
acl Safe_ports port 280                  # http-mgmt
acl Safe_ports port 488                  # gss-http
acl Safe_ports port 591                  # filemaker
acl Safe_ports port 777                  # multiling http
acl Safe_ports port 631                  # cups
acl Safe_ports port 873                  # rsync
acl Safe_ports port 901                  # SWAT
acl purge method PURGE

http_access allow manager localhost
http_access deny manager
http_access allow purge localhost
http_access deny purge
http_access deny !Safe_ports
http_access deny CONNECT !SSL_ports
http_access allow localnet
http_access allow localhost

# And finally deny all other access to this proxy
http_access deny all

# -----------------------------------------------------------------------------
http_port 3128

# -----------------------------------------------------------------------------
#The memory needed for caching used files. The more you have the faster works. (No disk access.)
cache_mem 256 MB
#Objects bigger than this should be stored on the hard-drive. This can be lower than 8kb if your server has little memory.
maximum_object_size_in_memory 8 KB

# -----------------------------------------------------------------------------
#Make sure you have enough space. And mount this on a fast disk or a raid0.
##cache_dir ufs /var/squid/cache 1000 16 256
cache_dir diskd /var/squid/cache 500 16 256

#This is extremely useful if your users download big files. You can even increase this depending on usage.
maximum_object_size 40960 KB

# -----------------------------------------------------------------------------
#This logging format includes the date the address requested the IP address of the requestor and the AD user who made the request.
#Human resources need to know what your users browse during the workday.
logformat squid %tl %6tr %>a %Ss/%03Hs %<st %rm %ru %un %Sh/%<A %mt
#Where to store all of this data.
access_log /var/log/squid/access.log squid

# -----------------------------------------------------------------------------
cache_mgr admin@mycompany.net
mail_from squid@ mycompany.net
visible_hostname proxy

# -----------------------------------------------------------------------------
##You have the option to use the ISP’s DNS here
# dns_nameservers
hosts_file /etc/hosts
uri_whitespace allow
http_access deny all

#### --- End of the configuration file --- ####

– – – – – – – – – – – – – – – – – – – – – –

Run the command squid –z to let squid create the necessary directories.
#squid –z
Add the squid daemon to auto-startup, on a Debian machine the command is: 
#update-rc.d  squid defaults
Start squid
#/etc/init.d/squid start

Test squid without authentication first. If this works go to the next step.
To test without authentication, comment all of the parameters in the Authentication section by adding the “#” sign at the beginning of line and restart squid.

Add or remove daemons to autostart
cd /etc/init.d/
update-rc.d  winbind defaults
update-rc.d -f apache2 remove

Tweaking performance on SQUID

A few settings that can dramaticaly improve the performance on your proxy:

cache_dir ufs /var/spool/squid 1000 50 256
This is the default Squid storage type configuration.
Change the storage type from ufs to aufs if using a Linux or variants.
Change the storage type from ufs to diskd if using BSD or variants.
If you use Windows, is probably for testing purposes, or because you don’t have a machine. Once the testing is done change to Linux or BSD.
The numeric parameters are:
First parameter is the amount of disk space in Mbytes to be used by Squid. The more you use the more physical memory (RAM) you need for indexes in order to be effective.
The rule is that you need
If you want to use the whole drive’s, (partition), space make sure you subtract 20% and use that value. In other words you can only use 80% of the drive.
The second and third parameters are the number of first and second level subdirectories that are created.

cache_mem 64 MB
The more memory you have the better it performs. Local, (cached), objects are much faster to retrieve than external ones.
The more local objects you can store the faster Squid responds.
Squid uses cache for many things other than memory cache, so make sure you have enough memory left when you configure cache_mem.

Memory cache is better for speed than disk, but is lost more easily and you can get bigger cache total spending RAM on indexes.

maximum_object_size 20480 KB
Today’s Internet usage contains has a lot of traffic in the 2MB to 200MB range. This traffic is comprised of multimedia objects, update files, etc.
You need to investigate your traffic and see what is a good number for you.

maximum_object_size_in_memory 64 KB
If you have little memory keep the default 8 KB. It is better to serve more fast pages from memory than a few slow pages that will run faster.

Check if your proxy works and if is logging properly the access.
On your proxy machine run the following command to see realtime access on the proxy: tail -f /var/log/squid/access.log On a client computer open the browser of your choice and change Networking options so that the browser uses the newly installed proxy.
Start to browse and look on the proxy’s console to see your activity logged.

How to Troubleshoot Internet Connection Speed

Who didn’t have problems with the Internet speed at least once? OK, many of us, but as an IT professional I always meet and talk to the people who did have problems with their Internet Speed.
I hate to be run through standard procedure, which by the way I know by hearth, (I used to work in an ISP call center). You probably hate it too. If your problem is the Internet connection you will probably have to talk to an agent anyway, but, (with the help of my article), you will know from the start what’s wrong with your Internet connection.

Step 0 – Never Assume

First think I have learned in the Call Center was to never assume. Many times, when people call the Help Line they have a “pretty good idea” of what’s the problem. Usually they are wrong. Don’t do this mistake, do not presume or, do not presume without checking the facts. We hate the Call centers for making us do stupid things, check things that we don’t need to. The truth is that in most of the cases we overlook things and going by the book helps.
When we open up a browser and there is an error message “Page not found” we immediately assume that the connection is to blame. In fact many times this is just a temporary problem of our home page site. Try a different address to see if the connections is down or the home pages’s website is down. Try google.com for instance or ibm.com, or bing.com; if these don’t work it could be the connection

Step 1 – Try a reboot

Almost every time a reboot solves the problem. This might sound anecdotic but it actually works in many cases. Reboot the computer, reboot the modem, reboot the router behind the modem.

Isolate the problem
First of all we need to know that the problem is not in the network.

  • Use a computer that you are sure is not infected by any Mallware. Connect it directly to the DSL device, cable modem, or other type of modem.
  • Do not use the wireless; connect the computer with a network cable. This way you are testing the connection and nothing else.
  • As already mentioned, you need to make sure your computer works fine and is not infected. Use antivirus and antispyware if needed.
  • If you are not sure about the health of your computer you can always boot from a Live Linux CD. On the Live CD you will have a browser and other useful tools.
  • Once the system is up and you are connected to the Internet, test your connection with one of the free online services. Google-it and you will find many online DSL speed test websites. If the speed is OK then, the problem is in your computer, or your network, go to step 4.
  • Step 2 – Modem troubleshoot

    If the DSL speed test failed, (no connection or slow speed), you have a few things to try before calling the ISP
    Usually, for a DSL connection, the telephone line is shared with another device, a fax or a phone. Some of us have a separate line for DSL or they don’t even have a phone line, they only have a dry loop. If you don’t understand any of these you most likely don’t have it.

  • If you share the DSL line with another device you need to connect this second device through a DSL filter. I must stress: EVEN IF IT WORKED before without it, you must have the filter.
    DO NOT run the DSL line through a filter, you’ll only break your Internet Connection, only the phone or the fax, or Credit Card processing device, etc…
  • Check all the physical connections of the Modem Device, R6 or RJ11 or the RJ45 connectors and make sure that they are tight they don’t have the locking pins broken, etc…
  • For a DSL connection the length of the phone cable could be critical, so use the original cable, (the short one), provided with the modem at least for the testing period. The reason is because the length of the pair from the CO to your place can be at its length limits, it happens more often than you think. If you pass this limit your connection stability will be penalized. Another reason is because a long cable is more difficult to examine for defects than a short one.
    If needed, use a longer network cable to connect a device in the house. The network cable, (UTP – unshielded twisted pair), can go up to 100m (300 feet).
  • Some electric devices can interfere with the modem; avoid placing it near such devices.
  • Look at the modem’s lights. If the DSL light is off there is no service.
  • If there is no connection at all, (No DSL light), check the phone to see if you have a dial tone.
  • If the modem connects to a separate wall jack bring a phone and check if you have a dial tone, you might have a dial tone in the bedroom and not in the office.
  • Similarly check if there is TV service, if there is no TV service then most likely it is a bigger problem at your cable provider.
  • Look for the DSL filter as described above.
  • Check the LAN light on the modem. If the LAN LED is off your computer’s network adapter might be defective, or disabled, or the UTP cable that connects the computer with the modem might be defective. There is a chance that the modem’s LAN interface is defective.
  • If you have a solid DSL light, (check the modem’s manual, manufacturers have different signalling for established DSL connection), and you don’t have a connection check the password for the connection.
  • Step 3 – Connect to Your Modem’s Administration Interface

    All of the modern modems have a WEB Administration Interface. The admin Interface is usually accessible via a WEB browser. It lets you configure the authentication and other different settings.
    In order to administrate your modem you need the following:

  • The administrator’s password to access your router. If you don’t have it you can perform a hardware reset using the reset button located on the modem. You need to use a pin to press the button. This will reset all of your modem’s setting, including the admin password, to the factory defaults.
  • The IP address of the router. If the modem has its DHCP server started, (by default yes), it will lease your computer an IP address and provide it with other IP configuration settings such as: “Default Gateway”, netmask, and DNS. The important part is the gateway’s IP address as this is your modem’s internal interface and this is what you need to access your router’s web Interface. You can find all of this information by issuing the following command in a command prompt window with elevated rights, (admin credentials):
    ipconfig /all
    After issuing the command you will get a screen similar to this one. Note that the “Default Gateway” is the address of your modem.
    In a web browser type: http://IPADDRESS where IPADDRES is your router.
    For instance if your router’s (gateway) IP address is the address you are looking for is:
  • Once connected to the web interface you need to enter the authentication details. If you don’t have them you have to call your ISP which will make a reset after security verification.
  • If all of the previous steps did not solve the problem call your ISP. They might ask you to redo all of the steps above and maybe more. Be patient, they are just doing their job, they never assume, or they shouldn’t. The second they let themselves drawn into your speculation they make the same mistake as you do.

    Step 4 – Correct the problems behind the modem

    If the connection is OK the problem is behind the modem. This problem could be anything in your network.
    Some suggestions are:
    The router – many times the router can slow down your network. Try a reboot. If that doesn’t work try another model or another manufacturer. Do an upgrade of the firmware. Check the router’s configuration and try a default stripped down configuration.
    The computer – most of the times, the slow performance over Internet is actually the poor performance of a computer. This is a dense material that is treated in a separate article which you can find here: How to Refresh your Computer speed (coming soon).
    The network – many times a poor network will penalize al sorts of network traffic not only Internet. This makes the subject of another article here: How to Troubleshoot Your LAN, (Local Area Network). (coming soon)

    Ask me any technical question in the comments area so I can update the document or answer you directly on the comments. I would like to make this article as useful as possible.