[SOLVED] Is it possible to SSH to all network clients from a Bash exec?

Is it possible to SSH to all network clients from a Bash exec?

I'm writing a shell script that I want to be able to run some command, like arp -a, to get the IPs of everyone on the network and then try SSHing to each of them in turn. Problem is, I have no idea how to send the IPs from arp -a to the SSH command without typing the IP in manually (not going to work, as I'm writing an executable file.) Is this even possible?

Solution

Short answer: You can write a small script to extract the IP in from arp and process each one. You can use bash loop, or other tools (xargs) to process multiple IP.

Bash solution

#! /bin/bash
  # Read arp line like: '_gateway (192.168.215.3) at 00:52:58:e7:cf:5f [ether] on ens33`
while read tag ip x ; do
  # Strip leading and trailing characters from the IP
  ip=${ip:1:-1}
  # Execute ssh
  ssh ... "$ip"
done <<< "$(arp -a)"

Update bash version BEFORE 4.2:

Based on input in comment from @cyrus.

Using negative length on substring was added in bash 4.2. For older older versions, use the following instead of ip=${ip:1:-1} to remove leading '(' and trailing ')'

 ip=${ip#(} ; ip=${ip%)}