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38 lines
1.1 KiB
Bash
38 lines
1.1 KiB
Bash
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#!/usr/bin/env bash
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set -x
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# Require root or exit
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if [ "$(id -u)" != "0" ]; then
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echo "This script requires root. (And the 3 nameserver IPs as arguments)" 1>&2
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exit 1
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fi
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# Three arguments or quit.
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if [ $# -ne 3 ]; then
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echo "This script requires three arguments that will be passed as nameservers."
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exit 1
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fi
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# In case I am behind the /etc/resolv.conf, it's immutable and read-only,
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# which won't allow it to be rewritten.
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chattr -V -i /etc/resolv.conf
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chmod -v +w /etc/resolv.conf
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# Or it's a symlink to e.g. /run/systemd/resolve/stub-resolv.conf
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rm -v /etc/resolv.conf
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# No trust-ad here as chances are these resolvers are unencrypted and the
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# path to them isn't trusted.
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# tee -p = operate in a more appropriate MODE with pipes.
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printf "nameserver %b\nnameserver %b\nnameserver %b\nsearch .\noptions timeout:2 attempts:2 rotate edns0\n" "$1" "$2" "$3" | tee -p /etc/resolv.conf
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# Remove all other permissions than everyone reading resolv.conf
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chmod -v a=r /etc/resolv.conf
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# Make resolv.conf immutable again so it's pretty sure nothing else edits it.
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chattr -V +i /etc/resolv.conf
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# Let's just see it's ok
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ls -l /etc/resolv.conf
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cat /etc/resolv.conf
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set +x
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