Network Debugging Tools

ifconfig Configures the Network Interface

The ifconfig utility assigns an address to a network interface and configures network interface parameters. The ifconfig utility can be used at boot time to define the network address of each interface present on a machine. It may also be used at a later time to redefine an interface's address or other parameters.


arp Manipulates the System's ARP Cache

The arp command is used to view and change the address resolution table (ARP). The ARP, also called the ARP cache, lists all the data link protocols-to-IP mappings for the network. This command lets you view and modify the ARP cache. With the arp command, you can display the ARP cache, add ARP entries, and delete ARP entries.


tcpdump Dumps Traffic on a Network

With the tcpdump program you can view all or only certain packets going over the Ethernet. tcpdump can be used to debug network problems.

ethereal Interactively Browses Network Traffic

ethereal is a GUI network protocol analyzer. It lets you interactively browse packet data from a live network or from a previously saved capture file.


netstat Shows the Network Status

The netstat command symbolically displays the contents of various network-related data structures. It has a number of output formats, depending on the options for the information presented. The first form of the command displays a list of active sockets for each protocol. The second form presents the contents of one of the other network data structures according to the option selected. Using the third form, with a wait interval specified, netstat continuously displays information regarding packet traffic on the configured network interfaces. The fourth form displays statistics about the named protocol.


The next option for netstat is -tap, which is a good way to determine what programs are serving from your system It can be used to look for rogue connections to your server. One way to look for rogue connections is to check the local address for nonnormal ports. Once a nonnormal port is found, the PID and program name can be used to investigate the program and see why it is being served from your system.

The man pages can give you far more info on these and many other tools.

As always Thank you for Flying Penguin Air

I would recommend iftop has a good debugging tool too. Like top for processes, iftop shows your active network traffic. Can be handy for finding what's eating your bandwidth.

thanks bd

Hi guys...

Hope you can help me with setting up/using vpn.

Already downloaded kvpnc and tried knetwork manager, read a lot but i still feel lost.

any ideas.

maybe my question is "
creating a new profile in kvpnc, what I should put where? what do I need to install? what do I need to edit?

Any help highly appreciated.

Not sure if you've read this one yet limo, but its a good read. I would say start a new thread for more questions, as this is meant to be more of a thread about different network tools.


http://www.linuxjournal.com/magazine/paranoid-penguin-linux-vpns-openvpn-part-ii?page=0,1