IT Knowledge Base

Tracert like in windows wit ICMP Echo request
#traceroute www.google.com –I

Show Routing Table
# nestat –nr
# route –n

Connection Statistic
# nestat –i
# mii-diag

Network Connections and Bind Ports
# netstat –a

Check DNS Settings
# dig www.google.com
# dig www.google.com mx
# nslookup www.google.com

I had to install the packages first to use this commands:
# apt-get install dnsutils

TCPDUMP
It is a very useful Network Sniffer for Linux. But first you need to install it:
# apt-get install tcpdump

Ex.
# tcpdump –nli eth0 port 80
# tcpdump –nli eth0 host 192.168.1.100 and port 80
# tcpdump –nli eth0 host 192.168.1.00 and not port 22
# tcpdump –nli eth0 src host 192.168.1.00 and not port 22

Check the state
# ifconfig –a

Activate/Deactivate Network Interface
# ifup eth0
# ifdown eth0

Hostname
# hostname
# uname -n
# vi /etc/hostname

Get an IP from the DHCP Server
# dhclient

Edit this file to setup a fix IP
#vi /etc/network/interfaces

auto eth0
iface eth0 inet static
      address 192.168.0.25
      netmask 255.255.255.0
      network 192.168.0.0
      broadcast 192.168.0.255
      gateway 192.168.5.1

# /etc/init.d/networking restart

Edit this file to setup DNS
#vi /etc/resolv.conf

order hotsts, bind
domain mydomain.local
nameserver 192.168.0.10

Today I had to add a second virtual network in VMWare. Unfortunately I didn’t find any option first. To do this you need to actually power off the VMWare Host. Then go the settings of the VMWare Host. Click on Add Ethernet Card and confirm everything. Startup OS again.

You need to access your computer at home or company. Or do you need to fix you relatives computer but you are to lazy to get up from you chair and visit them. So you need a remote control software. You could use vnc or remote desktop etc. But usually they are behind a firewall and it needs first a lot of configuration. And not everybody knows how to make a ssh tunnel through port 80 to bypass the firewall. Anyway if you looking for a pretty good and fast solution that most of the time works have a look here:

www.logmein.com

It is by the way free to use, but there are a couple of limitations. One important feature which is missing in the free version is that you can’t share files. Still this service is great and helped me already a couple of times.