Author: Ruwantha Nissanka

Echoping is a simple linux tool that we can use to test the performance of a remote host (approximatively) by sending “echo” packets with TCP or UDP. After sending the “echo” packet, It will show the time taken to set up the TCP connection and to transfer the data. Execute the following command to install echoping #apt install echoping To test a remote machine with TCP echo (one test), use the following command #echoping <ip_address> To get a verbose output, use the -v option with the above command The following command will test the remote machine with 5 TCP echo tests, every ten seconds. #echoping -n 5 -w 10 <ip_address> You can use the HTTP protocol (instead of echo) for the given URL. If the hostname is the web server, the argument has to be a path, a relative URL (for instance ‘/’ or ‘/pics/foobar.gif’). If the hostname is a proxy/cache like Squid, the argument has to be an absolute URL. You can test the remote web server and asks its home page using the following command: #echoping -h / <example.com> To use UDP instead of TCP, use the -u option #echoping -u <ip_address> You can load a whois plugin and query a host, “-d tao.example.org” are options specific to the whois plugin. #echoping -n 3 -m whois <website_url> -d tao.example.org To send several UDP Echo packets with an IP Precedence of 5, use the following command #echoping -u -P 0xa0 <website_url> Below you can find some more...

As we have already discussed in one of our previous articles, ARP protocol  is commonly used by layer two devices to communicate and discover each other easily. The arping utility performs an action similar to ping, but at the Ethernet layer. Where we can use ping to tests the reachability of an IP address, arping can be used to report the reachability and round-trip time of an IP address hosted on the local network. You can use the following command to install arping in yur system #apt install arping Execute the following to check the version #arping -v To check the current ARP entries in your ARP table, issue the following command #arp  -a In this case, I am presented with the only entry in my ARP table : a router accessible via the 192.168.226.2 IP address. Execute the following command to ping a host using arping #arping -c 2 <ip_address> Here I have specified the number of pings to be sent using the “-c” option for “count”. As you can see, if you are getting response pings, you are presented with the MAC address of the corresponding device. You will have to specify the network interface if you have multiple network interfaces on your system. You can do it by using the following command #arping -I <interface_name> <ip address> You can specify the source MAC address you are sending packets from using the following command...

The tape archive (tar) command was originally designed to back up filesystems to tape devices. Although many people now use the tar command to back up to non-tape devices, you should be aware of how to use tape devices as well. For the following examples, we assume that you do not have a tape drive in your system. The examples provided for the tar command place the tar ball (the result of the tar command) in a regular file; however, if you have a tape drive, you can just replace the filename with your tape device file. To create a backup (or tar ball) with the tar utility, use the -c (create) option in conjunction with the -f (filename) option: #tar -cf <filename_to_be_created> <filename_to_be backed_up> The leading / characters are removed from the filenames, so instead of absolute pathnames being backed up, the pathnames are relative. This makes it easier to specify where the files are restored. Having the leading / would result in files always being stored in the exact same location. To see the contents of a tar ball, use the -t (table of contents) option in conjunction with the -f option, as shown below. #tar -tf <filename> You often want to see detailed information when listing the contents of the tar ball. Include the -v (verbose) option to see additional information, as shown in this command....