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lessavin/natcheck.sh

Last active November 18, 2025 21:35
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Returns 1 if ISP put you under NAT.
Raw
natcheck.sh
#!/usr/bin/sh
# natcheck.sh
# Returns 1 if ISP put you under NAT.
# Source: https://superuser.com/questions/1630106/how-do-i-find-out-if-my-isp-has-put-me-behind-a-nat-will-dynamic-dns-work-with
NATCHECK_HOPS=2 # Change this value to <rounter_number>+1.
if [ $NATCHECK_HOPS -lt $(traceroute $(curl -s ifconfig.me) | grep ms | wc -l) ]
then
exit 1
fi
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