Created
September 1, 2021 14:29
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Script to check for listening ports without using `netstat`
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#!/bin/sh | |
# Source: https://staaldraad.github.io/2017/12/20/netstat-without-netstat/ | |
awk 'function hextodec(str,ret,n,i,k,c){ | |
ret = 0 | |
n = length(str) | |
for (i = 1; i <= n; i++) { | |
c = tolower(substr(str, i, 1)) | |
k = index("123456789abcdef", c) | |
ret = ret * 16 + k | |
} | |
return ret | |
} | |
function getIP(str,ret){ | |
ret=hextodec(substr(str,index(str,":")-2,2)); | |
for (i=5; i>0; i-=2) { | |
ret = ret"."hextodec(substr(str,i,2)) | |
} | |
ret = ret":"hextodec(substr(str,index(str,":")+1,4)) | |
return ret | |
} | |
NR > 1 {{if(NR==2)print "Local - Remote";local=getIP($2);remote=getIP($3)}{print local" - "remote}}' /proc/net/tcp |
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