Hiii,
I am new to linux. and i have one security concern with my LAN premises. I have found that some one is sniffing packets over the LAN using free packet sniffing tool.
So, Now i want to block all the sniffing tools like packet sniffer, wire shark, etc..
You can't do that remotely. It has to be done on the linux box. Packet sniffing means that somebody with elevated privilege on a (linux) box set a NIC into promiscuous mode. You have to physically get on the linux box and stop whatever is going on there. Then remove privilege for all the users on the box & change root password. This will "block" it.
So, you have problems. Elevated privilege on a linux box and other security issues. As well as to why packet sniffing was set up.
I would simply speak with the admin on the box to find out what is going on. The admin may be running something for security. e.g., snort