How to show console resolution in Ubuntu

To print console resoluton in Ubuntu:

cat /sys/class/graphics/fb0/virtual_size

Installation Wireshark on Ubuntu

Wireshark is a free and open-source packet analyzer. It is used for network troubleshooting, analysis, software and communications protocol development, and education. It is a very good helper of a network administrator and it rescued my network many times. You can install it on Ubuntu by running following commands in terminal:

sudo add-apt-repository ppa:n-muench/programs-ppa
sudo apt-get update
sudo apt-get install wireshark

D-Link DES-3550 ACL configuration

To disable users with ip-addresses from subnet 192.168.0.0/16

 create access_profile ip source_ip_mask 255.255.0.0 profile_id 1
 config access_profile profile_id 1 add access_id 1 ip source_ip 192.168.0.0 port 1 deny
 config access_profile profile_id 1 add access_id 2 ip source_ip 192.168.0.0 port 2 deny