Bash Script for Key‑Based Multi‑Host SSH Access

This article provides a complete Bash script that enables password‑less SSH access to multiple Linux hosts using key authentication.

First, the script defines a password and the target subnet range, then discovers live IP addresses by pinging each address from the third to the last host in the subnet.

#!/bin/bash

PASS=123456

# 设置网段最后的地址

END=254

IP=`ip a s eth0 | awk -F '[ /]+ ' 'NR==3{print $3}'`

NET=${IP%.*}.

rm -f /root/.ssh/id_rsa

[ -e ./SCANIP.log ] && rm -f SCANIP.log

for((i=3;i<="$END";i++));do

ping -c 1 -w 1 ${NET}$i &> /dev/null && echo "${NET}$i" >> SCANIP.log &

done

wait

After discovering live hosts, the script generates an SSH key pair without a passphrase and ensures the sshpass utility is installed.

ssh-keygen -P "" -f /root/.ssh/id_rsa

rpm -q sshpass || yum -y install sshpass

It then copies the generated public key to each discovered host, enabling password‑less login.

sshpass -p $PASS ssh-copy-id -o StrictHostKeyChecking=no $IP

AliveIP=(`cat SCANIP.log`)

for n in ${AliveIP[*]};do

sshpass -p $PASS scp -o StrictHostKeyChecking=no -r /root/.ssh root@${n}:

done

Finally, the script distributes the .ssh/known_hosts file to all hosts so that the first mutual connection does not require manual confirmation.

# 把 .ssh/known_hosts 拷贝到所有主机，使它们第一次互相访问时不需要输入回车

for n in ${AliveIP[*]};do

scp /root/.ssh/known_hosts ${n}:.ssh/

done

The script concludes with a separator line indicating the end of the procedure.

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