Suricata

alert http $HOME_NET any -> $EXTERNAL_NET any (msg:"suri 5 pcre fun"; flow:established,to_server; http.method; content:"POST"; http.uri; content:".php"; http.header; content:"|0d 0a|User-Agent|0d 0a|"; content:!"Referer|3a 20|"; pcre:"/^(?:[A-F0-9]{2}){200,}$/P";)

This rule loads in suri 5 but does not fire on pcap. It seems that the sticky buffer is set and loads the pcre within the existing sticky buffer even though we specifiy the buffer for the pcre.

If the pcre is moved to the front of the rule, the rule fires as expected, example:
alert http $HOME_NET any -> $EXTERNAL_NET any (msg:"suri 5 pcre fun"; flow:established,to_server; pcre:"/^(?:[A-F0-9]{2}){200,}$/P"; http.method; content:"POST"; http.uri; content:".php"; http.header; content:"|0d 0a|User-Agent|0d 0a|"; content:!"Referer|3a 20|";)