36 lines
1.5 KiB
Bash
36 lines
1.5 KiB
Bash
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#!/bin/bash
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# This script will generate an IPv6 ULA. In IPv6, you know longer get to pick your favorite private network network and go for it,
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# you must accept a psuedorandom /48 out of the fd::/8 space. This script will generate a /48 for either deploying an isolated
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# ipv6 network that will almost certainly not conflict with present and future upstream ipv6 networks or just getting your feet wet
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# with ipv6
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# Implements RFC5193, section 3.2.2, with precision only down to nanoseconds at best (normalized by date output
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SECSDOTNANO=$(date +%s.%N|sed -e 's/\.0*/\./')
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NANOSECONDS=${SECSDOTNANO#*.}
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#Convert from nanoseconds to ntp fractional seconds (I'll call them ticks for convenience)
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# ns * 2**32 ticks/second * 1/1000000000 ns/s = ticks
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NTPTICKS=$(( ($NANOSECONDS<<32) /1000000000))
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EPOCHDELTA=2208988800
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SECONDS=${SECSDOTNANO%.*}
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SECONDS=$(($SECONDS+$EPOCHDELTA))
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TIMESTAMP=$(printf "%08X:%08X" $SECONDS $NTPTICKS)
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#next, get a mac address and convert to eui64
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EUIPAD="FF:FE"
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MAC=$(/sbin/ifconfig|grep HWaddr|grep -v usb|grep -v 00:00:00:00:00:00|head -n 1|awk '{print $NF}')
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FIRSTBYTE=${MAC%%:*}
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FIRSTBYTE=$(printf %02X $((0x$FIRSTBYTE|2)))
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OTHERMANUF=${MAC%%:??:??:??}
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OTHERMANUF=${OTHERMANUF#??:}
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LOWMAC=${MAC#??:??:??:}
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EUI=$FIRSTBYTE:$OTHERMANUF:$EUIPAD:$LOWMAC
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#now, to do the SHA, spec doesn't say much about encoding, so we'll just slap the data together the laziest way
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PREFIX="fd"$(echo $TIMESTAMP:$EUI|sha1sum|awk '{print $1}'|cut -c 31-)
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PREFIX=$(echo $PREFIX|sed -e 's/\(....\)/\1:/g')
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echo $PREFIX:/48
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