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Showing posts with label Basic and Advanced Users. Show all posts
Showing posts with label Basic and Advanced Users. Show all posts
Friday, 30 August 2013

25 computer networking tips and tricks

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25 computer networking tips and tricks

Tutorial How to set up and optimise your home network


25 computer networking tips and tricks
The redesigned Network and Sharing Center screen has lots of options for advanced users to play with
Running a home network is pretty essential in this day and age.
Thankfully, modern hardware and software has reduced the complexities of configuring networks down to a few setup screens, and the relevant hardware often comes free with an internet connection.
If you have multiple computers, the chances are they're already talking to each other, either through wires or wirelessly. However, while your home network might be up and running, optimising it takes some doing. Follow our simple tips to extract the last drop of juice from your network hardware.
1. Change channel number
Wireless routers operate on a fixed channel. Since most routers ship with a pre-selected channel, the wireless signal may interfere with other routers in the vicinity that are operating on the same channel.
Changing the wireless channel from the factory default is a good starting point if your wireless signal strength is poor.
2. Give the router space to breathe
The biggest advantage of a wireless router is that it can penetrate doors and walls – but that doesn't mean you can just stuff it next to a wall or cordless telephone, or use it as a stand for your stack of DVDs. Treat it with respect.
Try to keep it in a central location, away from other wireless devices; make sure it's not in direct sunlight; lift it off the carpet; and ensure its vents and air holes aren't covered.
3. Improve reception
Try as you might, you'll find it's sometimes not possible to put the router in a good spot. One way around the problem is to buy a router with multiple antennas and point them in a variety of directions covering your home.
Alternatively, if you've already got a router, check whether it's possible to upgrade its antennas to something stronger. However, don't get disheartened if your router doesn't have any antennas. A wireless repeater compatible with your router is a perfect solution.
4. Use WEP
Running an unsecured network will earn you brownie points from neighbours and hackers with cars, but that's about it. Wireless routers support a variety of encryption methods, such as WPA and WEP, but these aren't enabled by default.
WPA2 is the most secure method at the moment, but before deciding on an encryption method, make sure your network cards and adapters support it as well. Bear in mind that older machines – and games consoles such as the Nintendo DS – don't support WPA.
5. Restrict access to specific PCs
If you really don't want to use encryption, you can force your router to only connect to specific PCs. Your router identifies each computer by the unique MAC address of its network gear. Feed it a list of MAC addresses to connect to and you save yourself the trouble of entering a password each time you log in.
The disadvantage is that you'll have to add the MAC address of any new computer before it can get on your network – which is probably a more annoying way of getting things done.
6. Disable SSID broadcast
All wireless routers have a Service Set Identifier (SSID) that identifies them to network computers. Routers from the same manufacturer generally ship with the same SSID; 'Netgear' or 'Cisco', for example.
You should first change the SSID to something unique to set your router apart from those of your neighbours. Then, once all your hardware has been set up, it's better to turn off broadcasting the SSID altogether. This ensures your router isn't displayed in the list of available networks, and won't be a target for potential hackers.
7. Keep the firmware updated
Router manufacturers keep working on firmware, even after hardware has been shipped. In addition to tweaks in the user interface, new versions might make better use of the various components in the router, or add extra features.
Just like with an operating system, it's a good idea to upgrade the firmware of the router regularly – check the manufacturer's website for a new version. In the good old days, there was the risk of a botched firmware upgrade bricking your router, but it's a lot safer today.
8. Familiarise yourself with the router manager
All routers ship with a browser based manager. To use many of the tips in this article, you'll have to log in to this interface – try typing 192.168.1.1 into your web browser for the most common location.
It's a good idea to familiarise yourself with the various options and settings you can tweak from within this software. Many routers also have detailed documentation that's updated regularly, so hunt out the latest manual online.
9. Check your connections
There's nothing more irritating than receiving a 'cannot connect to remote machine' error. To ensure a solid connection, use Ethernet cables where possible. It's also a good idea to check the connection between the two PCs with the ping command.
To do this, simply open a command line and type, for instance, ping 192.168.1.2. You'll need to replace the address given here with that of your target machine. Ping works identically on Windows, Mac and Linux.
10. Forward ports
port forwarding
Many servers and applications – for example, file-sharing software, FTP servers and music-streaming servers – need to serve people outside the network. These applications accept connections on specific ports.
With port forwarding – check your router's interface – you can poke holes in your router and ask it to direct incoming traffic on a particular port (or, if you wish, a range of ports) to a specific computer that's on the network.
11. Change DNS providers
DNS is what fetches you a website by translating the human-friendly address, such as www.pcplus.co.uk, into a bunch of machine-friendly numbers. It also displays the '404 page not found' error, corrects misspelt URLs and finds the fastest route to a web server that hosts the site you want to visit, along with lots of other cool things.
Generally, it's up to the ISP to put up a DNS server. However, there are other free services as well, including the likes of OpenDNS and Google Public DNS.
12. Use USB adapters
These days, it's difficult to find a laptop or netbook without a built-in wireless module, but if you've used one, you'll know that they can't always be relied upon. Network cards with antennas are the best option, but they're really only suitable for desktops.
If you really need both mobility and assurance, make sure you get a USB adapter. Most of them ship with a Windows driver, but many work out-of-the-box on Linux as well.
13. Enable Dynamic DNS
The Dynamic DNS feature enables you to connect to your computer remotely. Back in the day, when real-estate on the web was expensive, it was a wonderful option to show off your HTML skills and host your own website.
Now, by associating your dynamic IP address with a domain name, DDNS enables you to connect to the internet-exposed home computer from anywhere in the world. In addition to enabling the feature on your router, you'll also have to register with a dynamic DNS provider, such as DynDNS.org.
14. Save power with Wake-on-LAN
What's the point of keeping a print server on when there's nothing to print? The smart way to save energy is to use the Wake-on- LAN feature of the network card. Thanks to this, you can put the machine to sleep after it's been configured to wake upon detecting network activity.
15. Encrypt your online activity
With the range of snooping tools now available, it isn't safe to do anything online without covering your footprints. There are lots of tools that promise to encrypt your online activity, making it completely unintelligible to anyone who might be listening in.
Some of the best ones to try are the Enigmail plug-in for Thunderbird, Psi for Google Talk and FireGPG, available for Gmail.
16. Get a Firewall distro
You can configure a firewall on a Windows or Linux machine, and there are also a bunch of third-party software firewalls available. However, building a firewall isn't easy. If you're serious about putting one up, download a dedicated firewall distro, such as Ebox.
17. Install the software
Ebox is distributed as a Live CD ISO and there are VirtualBox/VMWare images as well. It's based on Ubuntu Server 8.04. You can also pull in Ebox packages to a standard Ubuntu Server 10.04 installation. You can find it at www.ebox-platform.com.
18. Configure settings
Ebox can be adapted flexibly to your network. You can use it to restrict services that can be accessed and slice the network to keep some areas more secure than others. The distro runs a browser-based interface for adding, removing and configuring the components.
19. Filter content
Besides the firewall, intrusion detection (via Snort) and filtering content (via DansGuardian) are two other highlights of the distro. DansGuardian can also plug into the ClamAV antivirus scanner and filter content based on known virus signatures.
20. Exploit other features
In case you're still not satisfied, Ebox can also act as a gateway and provide a host of other services. It bundles various applications that enable you to turn your network into a VPN, host XMPP chat sessions or run a Postfix mail server, a Squid web proxy and more.
21. Turn on UPnP
Universal Plug and Play helps smart devices that support UPnP to discover each other without any user intervention. Once turned on from within your router, UPnP enables a compatible infrared device, a Bluetooth phone or a FireWire camera to see and talk to each other.
22. Write files remotely
The most logical use of a network is to share files. This is the job of the SMB protocol. Thanks to it, you'll be able to write files to a remote network share via Network Neighbourhood. On Linux, the SMB protocol is implemented by Samba.
23. Share printers remotely
In addition to sharing files, SMB can be used to share printers attached to a Windows machine. Once configured via the Windows Control Panel, a printer can be used to accept print orders or even be managed from a remote machine, irrespective of its operating system.
24. Format shareable partitions as FAT
PCs running Windows can easily see each other and share files. For Linux or Mac machines, ensure the partitions are formatted with the FAT filesystem. Create them as Samba shares and they'll show up under Network Neighbourhood.
25. Plug in USB drives
Once, if you wanted to share files on the network, a network-attached-storage, or NAS, device was the best bet. Not any more. New routers enable you to plug in one or more USB devices that are automatically accessible by all the users connected to the router.
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Monday, 26 August 2013

Ubuntu Networking for Basic and Advanced Users

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If you are new to networking the graphical configuration tool is your best method for configuring new hardware in Ubuntu.We are going to use GUI tool "network-admin" to configure networking. Remember, you must be root to run network-admin.
There are two ways to start network-admin first thing is you can use your terminal to type "sudo network-admin" it will start up or you can go to System--->Administration --->Networking

Once it opens you should see the following screen

In the above screen select wired connection and click on properties tab you should see the following screen my network card is curretly configured for DHCP client and you need to make sure "Enable this connection" tick box is checked

If you want to configure the Static ipaddress you need to select drop down box under "Configuration" select static ip address and you need to make sure "Enable this connection" tick box is checked

Once you select the static ip address you need to select ip address,subnet mask,gateway address and click on ok

Now you click on "General" tab here you can enter your hostname,domain name

Next one you need to click on "DNS" tab to configure your system's DNS settings, hostname, or DNS search path.

Click the Hosts tab, and then either click the Add or Properties button (after selecting a host) to create or edit an entry in your system's /etc/hosts file

Highlight an existing entry, and then click the Properties button to change /etc/hosts entries in the Hosts tab of the Network Configuration screen.

You can also assign different locations to your computer, especially very useful if you are on a laptop and move between several networks each requiring different configurations. Just select the gray bar at the top of the network-admin window and select Create Location. Enter a name, such as Home and then repeat this again to create another location, Work. Each time you switch between locations, Ubuntu detects that it needs to use configurations specific to those locations, so for instance you might want to use DHCP at work, but not at home. Simple; just select the Home location, configure your ethernet connection to use a Static IP and you are all set to switch between your home and corporate networks.

Configure Network Interface Using Command-Line
You can configure a network interface from the command line using the networking utilities. You configure your network client hosts with the command line by using commands to change your current settings or by editing a number of system files.
Configuring DHCP address for your network card
If you want to configure DHCP address you need to edit the /etc/network/interfaces and you need to enter the following lines replace eth0 with your network interface card
sudo vi /etc/network/interfaces
# The primary network interface -- use DHCP to find our address
auto eth0
iface eth0 inet dhcp
Configuring Static IP address for your network card
If you want to configure Static IP address you need to edit the /etc/network/interfaces and you need to enter the following lines replace eth0 with your network interface card
sudo vi /etc/network/interfaces
# The primary network interface
auto eth0
iface eth0 inet static
address 192.168.3.90
gateway 192.168.3.1
netmask 255.255.255.0
network 192.168.3.0
broadcast 192.168.3.255
After entering all the details you need to restart networking services using the following command
sudo /etc/init.d/networking restart
Setting up Second IP address or Virtual IP address in Ubuntu
If you are a server system administrator or normal user some time you need to assign a second ipaddress to your Ubuntu machine.For this you need to edit the /etc/network/interfaces file and you need to add the following syntax.Below one is the only example you need to chnage according to your ip address settings
sudo vi /etc/network/interfaces
auto eth0:1
iface eth0:1 inet static
address 192.168.1.60
netmask 255.255.255.0
network x.x.x.x
broadcast x.x.x.x
gateway x.x.x.x
You need to enter all the details like address,netmask,network,broadcast and gateways values after entering all the values save this file and you need to restart networking services in debian using the following command to take effect of our new ipaddress.
After entering all the details you need to restart networking services using the following command
sudo /etc/init.d/networking restart
Setting your ubuntu stytem hostname
Setting up your hostname upon a ubuntu installation is very straightforward. You can directly query, or set, the hostname with the hostname command.
As an user you can see your current hostname with
sudo /bin/hostname
Example
To set the hostname directly you can become root and run
sudo /bin/hostname newname
When your system boots it will automatically read the hostname from the file /etc/hostname
If you want to know more about how to setup host name check here
Setting up DNS
When it comes to DNS setup Ubuntu doesn't differ from other distributions. You can add hostname and IP addresses to the file /etc/hosts for static lookups.
To cause your machine to consult with a particular server for name lookups you simply add their addresses to /etc/resolv.conf.
For example a machine which should perform lookups from the DNS server at IP address 192.168.3.2 would have a resolv.conf file looking like this
sudo vi /etc/resolv.conf
enter the following details
search test.com
nameserver 192.168.3.2
Network Troubleshooting Tips
Networking is sometimes considered to be complex, and hard to troubleshoot and manage. However, Linux provides you with Some tools to figure out exactly what's going wrong on your network, and how to fix it.Here we are going see some tools and how to check the network connectivity.
Ping
Ping is a computer network tool used to test whether a particular host is reachable across an IP network. Ping works by sending ICMP “echo request” packets to the target host and listening for ICMP “echo response” replies (sometimes dubbed "Pong!" as an analog from the Ping Pong table tennis sport.) Using interval timing and response rate, ping estimates the round-trip time (generally in milliseconds although the unit is often omitted) and packet loss (if any) rate between hosts.
This is very basic and powerful tool to check Internet connection
Example
ping -c 4 google.com
-c option is used to pass how many packets you're sending
If everything working file you should get reply looks like below
Pinging www.l.google.com [64.233.183.103] with 32 bytes of data:
Reply from 64.233.183.103: bytes=32 time=12ms TTL=244
Reply from 64.233.183.103: bytes=32 time=12ms TTL=244
Reply from 64.233.183.103: bytes=32 time=12ms TTL=244
Reply from 64.233.183.103: bytes=32 time=12ms TTL=244
Ping statistics for 64.233.183.103:
Packets: Sent = 4, Received = 4, Lost = 0 (0% loss),
Approximate round trip times in milli-seconds:
Minimum = 12ms, Maximum = 12ms, Average = 12ms
Traceroute
traceroute is a computer network tool used to determine the route taken by packets across an IP network. An IPv6 variant, traceroute6, is also widely available.Very useful to trace IP packets.
Example
traceroute google.com
ifconfig
The Unix command ifconfig can function as a tool to configure a network interface for TCP/IP from the command line interface (CLI).This is another easy tool to see if your interface is actually loading correctly.
Example
ifconfig
eth0 Link encap:Ethernet HWaddr 00:0A:E6:C6:07:85
inet addr:132.18.0.16 Bcast:132.18.0.255 Mask:255.255.255.0
inet6 addr: fe80::20a:e6ff:fec6:785/64 Scope:Link
UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1
RX packets:18458 errors:0 dropped:0 overruns:0 frame:0
TX packets:8982 errors:0 dropped:0 overruns:0 carrier:0
collisions:0 txqueuelen:1000
RX bytes:4015093 (3.8 MiB) TX bytes:1449812 (1.3 MiB)
Interrupt:10 Base address:0xd400
Route
This is very useful to check routing config
Example
route -n
Netstat
If you want to see Routing Tables,all open ports,all listen ports
netstat -nr
-n means return numeric output (ie, IP address instead of hostname)
-r means print the routing table
find all open ports
netstat -a
find listening ports
netstat -l
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