Networking

You Cannot Connect to the Internet After You Connect to a VPN Server

This issue may occur if you configure the VPN connection to use the default gateway on the remote network. This setting overrides the default gateway settings that you specify in your Transmission Control Protocol/Internet Protocol (TCP/IP) settings.

A step by step Guide to isntall Nagios client

Procedure to isntall Nagios client : ————————————- 1) useradd -M -s /sbin/nologin nagios 2) Check 32bit or 64 bit OS by uname -a Depending on that, download appropriate version 3) tar -xvf nagios.tar.gz 4) cd nagios yum install perl-Digest-HMAC (This is a dependency, will install 2 rpms) perl-Digest-SHA1-2.11-1.2.1 perl-Digest-HMAC-1.01-15 rpm -ivh *.rpm 5) Put below [...]

Troubleshoot TCP/IP connectivity issues with PortQry – Port Scanner Version 2.0

Portqry.exe is a command-line utility that you can use to help troubleshoot TCP/IP connectivity issues. Portqry.exe runs on Windows 2000-based computers, on Windows XP-based computers, and on Windows Server 2003-based computers. The utility reports the port status of TCP and UDP ports on a computer that you select. Portqry.exe reports the status of a TCP/IP [...]

How to test your ISP for shaping your traffic

Test if your ISP is shaping your traffic Is there any way to find out what your ISP is giving to you?  Is he restricting your traffic?  Now There is a free utility called Glasnost project which test your ISP . The goal of the Glasnost project is to make ISPs’ traffic shaping policies transparent [...]

UltraVNC 1.0.9.4- Display the screen of another computer (via internet or network) on your own screen!

UltraVNC 1.0.9.4 allows you to use your mouse and keyboard to control the other PC remotely. It means that you can work on a remote computer, as if you were sitting in front of it, right from your current location. If you provide computer support, you can quickly access your customer’s computers from anywhere in the [...]

How to Build a diskette-based bandwidth management system – PicoBSD

Many users, despite having a good Net connection, complain about poor surfing and download speeds. While an organization could pay for additional bandwidth, a better option might be to manage the bandwidth they already have. There are numerous bandwidth management software tools available. In this article we will explore managing network bandwidth using the dummynet [...]

An Introduction to Basic IPv4 Routing

All of the operations considered in this article are operations upon a router, whether that router is a Linux box or Cisco dedicated hardware or some other type of machine. In this chapter I consider the traditional methods of IPv4 routing as using static configurations that are manually input by the network administrator. 1.1 Traditional [...]

How to Manage repositories in SVN

Subversion manages branches a bit differently than CVS; there’s a good document (SVN for CVS users) at the Subversion site. You should read that. The long short of it is that you have to restructure your directories a little bit before using Subversion. Caveat: this restructuring isn’t neccessary, and the following tree hierarchy isn’t neccessarily [...]

IPv6 addresses: why such a high number of bits?

During the design of IPv4, people thought that 32 bits were enough for the world. Looking back into the past, 32 bits were enough until now and will perhaps be enough for another few years. However, 32 bits are not enough to provide each network device with a global address in the future. Think about [...]

Why is the name IPv6 and not IPv5 as successor for IPv4?

On any IP header, the first 4 bits are reserved for protocol version. So theoretically a protocol number between 0 and 15 is possible: 4: is already used for IPv4 5: is reserved for the Stream Protocol (STP, RFC 1819 / Internet Stream Protocol Version 2) (which never really made it to the public) The [...]

What is IPv6 – What do IPv6 addresses look like

IPv6 is a new layer 3 protocol (see linuxports/howto/intro_to_networking/ISO – OSI Model) which will supersede IPv4 (also known as IP). IPv4 was designed long time ago (RFC 760 / Internet Protocol from January 1980) and since its inception, there have been many requests for more addresses and enhanced capabilities. Latest RFC is RFC 2460 / [...]

How to do a Simple Network Performance Test – Linux

FTP on Linux and other Unix systems allows you to pass shell commands to the ftp client by using the pipe symbol ‘|’ as the first character of the file name. With this feature you can send a very large file to a remote host using /dev/zero as input and /dev/null as output.

How to setup NIC team on a HP ProLiant DL 380 for fault tolerance and Load Balance

NIC teaming is the process of grouping together several physical NICs into one single logical NIC, which can be used for network fault tolerance and transmit load balance. The process of grouping NICs is called teaming. Teaming has two purposes: • Fault Tolerance: By teaming more than one physical NIC to a logical NIC, high [...]

RJ-45 Pinouts – straight through, cross-over and roll-over cables

The 8 Position 8 Contact (8P8C) modular plugs and sockets are communications connectors. Under the same naming scheme, an 8P6C connector has eight positions, with six positions containing conductors, and a 6P6C connector has six positions, all containing conductors. 8P8C connectors are typically used to terminate twisted pair cable.
These connectors are often called RJ45 plugs and sockets. This is technically incorrect because the RJ45 standard specifies the mechanical interface but a different wiring scheme than T568A/B, which is often used for Ethernet and telephones.
8P8C consists of two paired components: the male plug and the female socket. Each has eight equally-spaced conductors. On the plug, these conductors are flat contacts positioned parallel with the connector body. Inside the socket, the conductors are suspended diagonally toward the insertion interface. When an 8P8C plug is mated with an 8P8C socket, the conductors meet and create an electrical connection. Spring tension in the socket’s conductors ensure a good interface with the plug and allow for slight travel during insertion and removal. The 8P8C connector is probably best known for its use in Ethernet. Since about 2000, it is nearly universal as the type of connector used on a cable that carries a single Ethernet network, and has replaced many older connector types. Older connectors have also been phased out as modern cables no longer have the high current and voltage requirements for which the bulkier connectors were designed.

How to Install and Upgrade Squid

If you are currently running a rpm-based squid binary, and you have just made a fresh fedora installation, here’s an on how to upgrade and install your currently running Squid proxy web caching server. By definition: Squid is a high-performance proxy caching server for Web clients, supporting FTP, gopher, and HTTP data objects. Unlike traditional caching [...]