modsecurity: SecRule REQUEST_METHOD "!^OPTIONS$" "t:none"

Modsecurity question...

What is the REQUEST_METHOD test doing in the following? It appears twice.

SecRule REQUEST_METHOD "!^OPTIONS$" "t:none"

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SecRule &REQUEST_HEADERS:Accept "@eq 0" \
    "chain,phase:2,skip:1,t:none,deny,log,auditlog,status:400,msg:'Request Missing an Accept Header', severity:'2',id:'960015',tag:'PROTOCOL_VIOLATION/MISSING_HEADER'"
SecRule REQUEST_METHOD "!^OPTIONS$" "t:none"
SecRule REQUEST_HEADERS:Accept "^$" \
    "chain,phase:2,t:none,deny,log,auditlog,status:400,msg:'Request Missing an Accept Header', severity:'2',id:'960015',tag:'PROTOCOL_VIOLATION/MISSING_HEADER开发者_如何学C'"
SecRule REQUEST_METHOD "!^OPTIONS$" "t:none"
SecRule &REQUEST_HEADERS:User-Agent "@eq 0" \
    "skip:1,phase:2,t:none,deny,log,auditlog,status:400,msg:'Request Missing a User Agent Header',id:'960009',tag:'PROTOCOL_VIOLATION/MISSING_HEADER',severity:'4'"
SecRule REQUEST_HEADERS:User-Agent "^$" \
    "t:none,deny,log,auditlog,status:400,msg:'Request Missing a User Agent Header',id:'960009',tag:'PROTOCOL_VIOLATION/MISSING_HEADER',severity:'4'"
SecMarker 969999

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Please, don't explain the whole thing, I can read everything else. It looks like the REQUEST_METHOD test, however, is some sort of voodoo...

BTW, the test of the Accept is wrong. The Accept option is not mandatory as per HTTP.

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Although the Rule SecRule REQUEST_METHOD "!^OPTIONS$" "t:none" appeared twice but each time it is chained with another rule.

Chain is an action in ModSecurity that combine two or more Rules to form a single Rule.

1st rule is now:

SecRule &REQUEST_HEADERS:Accept "@eq 0" \
   "chain,phase:2,skip:1,t:none,deny,log,auditlog,status:400,msg:'Request Missing an Accept Header', severity:'2',id:'960015',tag:'PROTOCOL_VIOLATION/MISSING_HEADER'"
SecRule REQUEST_METHOD "!^OPTIONS$" "t:none"

2nd rule is now:

SecRule REQUEST_HEADERS:Accept "^$" \
    "chain,phase:2,t:none,deny,log,auditlog,status:400,msg:'Request Missing an Accept Header', severity:'2',id:'960015',tag:'PROTOCOL_VIOLATION/MISSING_HEADER'"
SecRule REQUEST_METHOD "!^OPTIONS$" "t:none"