Make public ip alias working again

See mathiasbynens#945

stow/shell/dot-aliases

@@ -51,7 +51,8 @@ alias week='date +%V'
 alias update='sudo softwareupdate -i -a; brew update; brew upgrade; npm install npm -g; npm update -g' # gem updating is problematic on Mojave; sudo gem update --system; sudo gem update; sudo gem cleanup'
 
 # IP addresses
-alias ip="dig +short myip.opendns.com @resolver1.opendns.com"
+alias ip{4,}='dig @resolver4.opendns.com myip.opendns.com +short -4' #you can use ip4 or ip to get your ipv4
+alias ip6='dig @ns1.google.com TXT o-o.myaddr.l.google.com +short -6' #https://unix.stackexchange.com/a/81699
 alias localip="ipconfig getifaddr en0"
 alias ips="ifconfig -a | grep -o 'inet6\? \(addr:\)\?\s\?\(\(\([0-9]\+\.\)\{3\}[0-9]\+\)\|[a-fA-F0-9:]\+\)' | awk '{ sub(/inet6? (addr:)? ?/, \"\"); print }'"