SSH login without password Ssh is commonly used when configuring or administering remote web servers. Now if you are working on some webserver regularly and find it tiring to type in the ssh password again and again, then it might be a good option to setup the login such that it does not ask for the password. Yes it is possible to make the ssh login without password. However this does not mean that the [...]

Many applications do not directly support the use of socks proxy. Torsocks enables such applications to use the tor socks proxy. Shell wrapper to simplify the use of the torsocks library to transparently allow an application to use a SOCKS proxy. Torsocks gets installed along with the tor package on ubuntu for example $ sudo apt-get install tor Proxify applications Lets say we want to proxify the telnet command to connect through a proxy. This [...]

In a previous article we saw how a windows netbook/laptop can be used to share a tata photon connection with other computers on a LAN. Now we shall do the same thing on Ubuntu. The technique is very simple and uses a tool called firestarter. Internet connection sharing can be setup on linux by adding rules to iptables, however it is not very user friendly and difficult for users with no previous experience of Linux. [...]

Wired Network Lets say you have an existing wired network setup at your workstation or home somewhat like this Adsl Modem/Router (192.168.1.1) => Switch => Multiple Pcs (192.168.1.10, 192.168.1.20 …) Now you want to add a wireless access point to this existing wired network so that you can connect to the internet wirelessly from your laptop, netbook or ipad (ipads are wifi only). For this you can use a wireless router from dlink for example. [...]

Tcpdump Tcpdump is a commandline network analyzer tool or more technically a packet sniffer. It can be thought of as the commandline version of wireshark (only to a certain extent, since wireshark is much more powerful and capable). As a commandline tool tcpdump is quite powerful for network analysis as filter expressions can be passed in and tcpdump would pick up only the matching packets and dump them. In this tutorial we are going to [...]

The standard telnet utilities that ship with linux or windows allow to telnet to services running on TCP ports. They do not support udp ports. However the utility netcat can be used for working with udp ports in a very similar manner to default telnet utility. The telnet utility works like this $ telnet localhost 7000 where localhost is the hostname and 7000 is the port number. For udp ports the syntax for netcat is [...]

The speed of your internet browsing depends on the dns servers to a certain extent. Whenever a url is opened in the browser, the browser has to first perform a dns request to get the ip address of that particular url’s domain name. For example www.google.com. It is only after the ip address is found, can the browser proceed further with loading the web page by sending http requests. So the speed factor depends on [...]

Port forwarding is a configuration in the router of a LAN such that any connections to a specific port number on the public/wan ip of the router may be forwarded to a specific machine/ip inside the LAN. Most routers allow configuration options to set port forwarding. After setting up port forwarding its necessary to check if its working or not. To check port forwarding 2 things are necessary : 1. An application on local computer [...]

Ipmango.com has dns information tool which provides various types of dns information about a domain name. The tool provides the following information about a domain name : Top level domain (TLD) nameservers TLD nameservers are those nameserver which provide the nameservers of a child domain name. For example the TLD nameserver of .com domains is A.GTLD-SERVERS.NET , B.GTLD-SERVERS.NET etc. So they can provide the nameserver of any .com domain TLD may also provide the IP [...]

Traceroute is an application that shows all the network points/hosts between 2 hosts on a certain network. For example , between you and www.google.com To perform a traceroute on Windows simply open your terminal/console and use the tracert command : On Ubuntu use the traceroute command : So the traceroute command shows the ip of all network hosts between our computer and www.google.com server Plot on world map Now that we have all the ips [...]