Created
April 26, 2014 19:24
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I found a very useful script that creates rules dynamically for specific hosts in this blog. The script needs to be run with cron, so it can lookup a hostname and add/delete rules in case the IP changed. The content of /etc/ufw-dynamic-hosts.allow could look like this: tcp:22:yourpc.no-ip.org and a crontab entry for executing the script every fi…
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#!/bin/bash | |
HOSTS_ALLOW=/etc/ufw-dynamic-hosts.allow | |
IPS_ALLOW=/var/tmp/ufw-dynamic-ips.allow | |
add_rule() { | |
local proto=$1 | |
local port=$2 | |
local ip=$3 | |
local regex="${port}\/${proto}.*ALLOW.*IN.*${ip}" | |
local rule=$(ufw status numbered | grep $regex) | |
if [ -z "$rule" ]; then | |
ufw allow proto ${proto} from ${ip} to any port ${port} | |
else | |
echo "rule already exists. nothing to do." | |
fi | |
} | |
delete_rule() { | |
local proto=$1 | |
local port=$2 | |
local ip=$3 | |
local regex="${port}\/${proto}.*ALLOW.*IN.*${ip}" | |
local rule=$(ufw status numbered | grep $regex) | |
if [ -n "$rule" ]; then | |
ufw delete allow proto ${proto} from ${ip} to any port ${port} | |
else | |
echo "rule does not exist. nothing to do." | |
fi | |
} | |
sed '/^[[:space:]]*$/d' ${HOSTS_ALLOW} | sed '/^[[:space:]]*#/d' | while read line | |
do | |
proto=$(echo ${line} | cut -d: -f1) | |
port=$(echo ${line} | cut -d: -f2) | |
host=$(echo ${line} | cut -d: -f3) | |
if [ -f ${IPS_ALLOW} ]; then | |
old_ip=$(cat ${IPS_ALLOW} | grep ${host} | cut -d: -f2) | |
fi | |
ip=$(dig +short $host | tail -n 1) | |
if [ -z ${ip} ]; then | |
if [ -n "${old_ip}" ]; then | |
delete_rule $proto $port $old_ip | |
fi | |
echo "Failed to resolve the ip address of ${host}." 1>&2 | |
exit 1 | |
fi | |
if [ -n "${old_ip}" ]; then | |
if [ ${ip} != ${old_ip} ]; then | |
delete_rule $proto $port $old_ip | |
fi | |
fi | |
add_rule $proto $port $ip | |
if [ -f ${IPS_ALLOW} ]; then | |
sed -i.bak /^${host}*/d ${IPS_ALLOW} | |
fi | |
echo "${host}:${ip}" >> ${IPS_ALLOW} | |
done |
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Where do I replace my stuff ??