alert http $HOME_NET any -> $EXTERNAL_NET any (msg:"ET POLICY Dyndns Client IP Check"; flow:established,to_server; http.user_agent; content:"DynDNS-Client"; depth:13; http.host; content:"checkip.dyndns."; classtype:not-suspicious; sid:2014091; rev:4; metadata:created_at 2012_01_03, signature_severity Informational, updated_at 2020_08_18;)