44 lines
1.1 KiB
Plaintext
44 lines
1.1 KiB
Plaintext
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#!/bin/bash
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unwind() {
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ip route del "$1/32" 2>/dev/null
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exit
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}
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short_route() {
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ip route | sed -n "s/$1 \\(.* dev [^ ]\\+\\).*/\\1/p" | head -n 1
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}
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resolve_ip() {
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local filter='/^[0-9]\{1,3\}\.[0-9]\{1,3\}\.[0-9]\{1,3\}\.[0-9]\{1,3\}$/{p;q;}'
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[[ $(sed -n "$filter" <<<"$1") == "$1" ]] && echo "$1" ||
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host -t a "$1" | cut -d ' ' -f 4 | sed -n "$filter"
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}
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set_route() {
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local default_route="$(short_route default)"
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[[ -n $default_route ]] || { echo "[-] Could not determine default route"; return; }
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echo "[+] Adding route for $1 to be $default_route"
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ip route del "$1/32" 2>/dev/null
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ip route add "$1/32" $default_route
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}
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check_loop() {
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local ip="$(resolve_ip "$1")"
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[[ -n $ip ]] || { echo "[-] Could not determine IP of '$1'" && return 1; }
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echo "[+] Making sure $ip goes over the default (non-0/1,128/1) route"
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set_route "$ip"
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trap unwind INT TERM EXIT
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while read; do
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[[ $(short_route "$ip") != "$(short_route default)" ]] && set_route "$ip"
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done < <(exec ip monitor route)
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}
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[[ $# -ne 1 ]] && { echo "Usage: $0 IP|HOST" >&2; exit 1; }
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[[ $UID -ne 0 ]] && exec sudo "$(readlink -f "$0")" "$@"
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check_loop "$1"
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exit $?
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