# icanhazip.com
wget -qO - http://icanhazip.com

# dyndns.org
wget http://checkip.dyndns.org/ -q -O - |
    grep -Eo '\<[[:digit:]]{1,3}(\.[[:digit:]]{1,3}){3}\>'

# whatismyip.com
curl https://whatsmyip.com/ -s | 
    grep -oE "\b([0-9]{1,3}.){3}[0-9]{1,3}\b" -m1

# google.com
curl https://www.google.com/search?q=what+is+my+ip+address -s | 
    grep -oE "\b([0-9]{1,3}.){3}[0-9]{1,3}\b" -m1

# ipecho.net
curl -s http://ipecho.net/plain

# akamai.com
curl -s http://whatismyip.akamai.com

# ipecho.net
wget -qO- http://ipecho.net/plain

# ipinfo.io
curl https://ipinfo.io/ip

# google.com
dig @ns1.google.com TXT o-o.myaddr.l.google.com +short

# opendns.com
dig +short myip.opendns.com @resolver1.opendns.com

# opendns.com
host myip.opendns.com resolver1.opendns.com | 
    grep -m2 -oE "\b([0-9]{1,3}.){3}[0-9]{1,3}\b" | tail -n1

# google.com
nslookup -query=TXT o-o.myaddr.l.google.com ns1.google.com | 
    grep -m2 -oE "\b([0-9]{1,3}.){3}[0-9]{1,3}\b" | tail -n1

# opendns.com
nslookup myip.opendns.com resolver1.opendns.com | 
    grep -m2 -oE "\b([0-9]{1,3}.){3}[0-9]{1,3}\b" | tail -n1