Linux Ask! is a Q & A web site specific for Linux related questions. Questions are collected, answered and audited by experienced Linux users.
Block website access in Linux
Answer:
The simple way to block access to web site is to change the hosts file.
1. Open the hosts file
# sudo vi /etc/hosts
2. Change the content, such as...
0.0.0.0 microsoft.com
0.0.0.0 oracle.com
3. Save the file.
Send ARP REQUEST to a neighbour host in Linux
Answer:
The arping command allow you to Ping destination on device interface by ARP packets, using source address source.
E.g.
# arping -U 192.168.1.5
The above command send an Unsolicited ARP request to update neighbours' ARP caches.
Check remote hostname using nslookup
Answer:
You can find the hostname of remote machine using the nslookup command.
# nslookup 198.182.196.48 | grep name
48.196.182.198.in-addr.arpa name = linux.org.
Check for the number of connection from a particular IP address
Answer:
You can check the total number of connections from a particular IP address:
# netstat -ntu | awk '{print $5}'| cut -d: -f1 | sort | uniq -c | sort -nr | more
It will give something like:
25 192.168.1.2
13 192.168.1.3
..
Fix the warning of: Remote Host Identification Has Changed error and solution
Answer:
You might experience this error, especially when you are connecting to a remote Linux machine which has just got re-installed.
To solve this, enter the command:
# ssh-keygen -R 192.168.2.36
Where 192.168.2.36 is the IP you are connecting.
