Posts

Showing posts with the label grep

Ping Multiple Hosts Using Bash Nmap and Fping

Image
I explained how to get a list of hosts using nmap -- using-nmap-to-generate-host-lists.html , but here is another look at the subject. The question is, how do I ping multiple hosts to find out which ones are down? Sure this could be considered a topic of system monitoring, but maybe you just want to reboot a bunch of machines, and make sure they all come back online. This quick check will tell you whether there is a problem or not. Here are three methods for pinging a list of hosts: 1.) for host in `cat all.txt `;do ping -c 1 $host; done 2.) nmap -sP -R -iL all.txt 3.) sudo fping -u < xyz/all.txt First, we assume that you have a text file named all.txt that contains a list of hostnames, one per line. Obviously, the examples here contain fake hostnames, domain names and IPs, as described in another article about vi: vim-tips-search-and-replace.html . --- all.txt --- xyz-1 xyz-2 xyz-3 xyz-4 xyz-5 xyz-6 xyz-7 xyz-8 --- end all.txt --- 1.) Use a for loop in ...

Using nmap to Generate Host Lists

Image
An easy way to get a list of hosts from a single domain that you are a part of, is to query DNS host -l mydomain.com But that is not always practical. Sometimes you have machines that are in different domains, but they all are part of a network you manage. Rather than trying write a script that pings hosts and reports the output, just use nmap for a very fast scan. To scan all hosts in a list of subnets 1) Create a subnets.dat file with one subnet on each line: $ cat subnets.dat 192.168.0.* 192.168.1.* 2) Run nmap with the subnets.dat file as input $ nmap -sP -R -iL subnets.dat Reading target specifications from FILE: subnets.dat Starting nmap V. 3.00 ( www.insecure.org/nmap/ ) Host (192.168.0.0) appears to be down. Host box1.mydomain.com (192.168.0.1) appears to be up. Host box2.mydomain.com (192.168.0.2) appears to be down. Host box3.mydomain.com (192.168.0.3) appears to be up. Host (192.168.0.4) appears to be up. ... Notice how names are resolved ...