show-hosts

#!/bin/bash

# this pulls mac addresses and IPv4 addresses from DHCP allocations that dnsmasq made

#set -x
cd /var/log
zcat syslog.4.gz syslog.3.gz syslog.2.gz |
  cat - syslog.1 syslog |
  grep -a dnsmasq-dhcp |
  grep -a DHCPACK |
  grep -a -v 'UFW BLOCK' |
  perl -p -e 's/^.*192\.168\.0\.\d+ (\S+).*$/$1/' |
  sort -u |
  while read i
    do echo $i
        j=`zcat syslog.4.gz syslog.3.gz syslog.2.gz |
          cat - syslog.1 syslog |
          grep -a -e "$i" |
          tail -n1`
        echo $i $j
        done |
        grep -a wingfly |
        sort |
        perl -p -e 'undef $_, next unless s/wingfly dnsmasq-dhcp\[\d+\]: DHCPACK\([^)]+\) (\S+) \S+/$1/; undef $b; if (s/(192\.168\.0\.\d+)$//) { $b=$1; chomp; $_ .= `avahi-resolve-address $b 2> /dev/null` ; chomp;
          unless (m/$b/) { s/$/$b/ } $_.="\n" }'

update-etc-hosts

#!/bin/bash

# update hosts file with current IPv6 addresses that hosts on my network are using

# run e.g. as:
#cat original-hosts > /etc/hosts ; while [[ 1 ]] ; do ./update-etc-hosts ; cat /etc/hosts ; head /etc/hosts ; sleep 60 ; done


#set -x
./show-hosts | tee show-hosts.output

# handle v6
conntrack -f ipv6 -L 2>/dev/null | perl -p -e 'while(s/^(.*?)(src|dst)=(\S+)/$2 $3 $1/) {}; s/^(.*(dst|src) \S+).*$/$1 /; s/(dst|src) //g; $_=join "\n", split; $_.="\n"' | sort -u | while read i ; do echo -n "$i " ; ip neigh show $i | grep lladdr | perl -p -e 's/^.*lladdr (\S+).*/$1 - good mac/; chomp;' ; echo ; done | grep 'good mac' | perl -p -e 's/ - good mac//' | while read i j ; do echo -n "$i " ; grep $j show-hosts.output ; done | perl -p -e 's/^(\S+) .*\s+(.+)$/$1 $2/' | grep -v '192\.168\.0' | while read i j ; do if grep -P "$i\\s" /etc/hosts ; then perl -p -i -e "s/$i\\s.*\$/$i $j/" /etc/hosts ; else echo $i $j >> /etc/hosts ; fi ; done

# handle avahi
cat show-hosts.output |grep -P '\.local$' | perl -p -e 's/^.*(192\S+).*$/$1/' | while read i ; do avahi-resolve-address $i ; done | perl -p -e 's/^(\S+)\s+/$1 /' | while read i j ; do if grep -P "$i\\s" /etc/hosts ; then perl -p -i -e "s/$i\\s.*\$/$i $j/" /etc/hosts ; else echo $i $j >> /etc/hosts ; fi ; done

# handle v4
for i in `seq 0 255` ; do grep -Pe "192\\.168\\.0\\.$i\s+" show-hosts.output ; done | perl -p -e 's/^.*(192\.168\.0\.\d+).*$/$1/' | sort -u | while read i ; do echo -n "$i " ; dig +short -x $i | perl -p -e 's/\.$//' ; echo ; done  | perl -p -e 'undef $_ unless m/^192\.168\.0\.\d+\s+\S/' | while read i j ; do if grep -P "$i\\s" /etc/hosts ; then perl -p -i -e "s/$i\\s.*\$/$i $j/" /etc/hosts ; else echo $i $j >> /etc/hosts ; fi ; done

# handle tailscale
tailscale status | grep -Pv '^\s*#|^\s*$' | perl -p -e 's/^(\S+)\s+(\S+).*$/$1 $2/' | while read i j ; do if grep -P "$i\\s" /etc/hosts ; then perl -p -i -e "s/$i\\s.*\$/$i $j/" /etc/hosts ; else echo $i $j >> /etc/hosts ; fi ; done