본문 바로가기

보안/study

tls fallback option

https://wiki.openssl.org/index.php/SSL_MODE_SEND_FALLBACK_SCSV

 

SSL MODE SEND FALLBACK SCSV - OpenSSLWiki

TLS_FALLBACK_SCSV is a TLS Signaling Cipher Suite Value (SCSV) that can be used to guard against protocol downgrade attacks. The extension can be useful for clients like web browsers, which fall back to a lesser protocol version if attempts to use a higher

wiki.openssl.org

 

 

 

 

 

 

fallback 

client 1.0(fallback) -> server 1.2 / 1.1 / 1.0

server 1.0 선택 안됨

 

 

client 1.0 - waf 1.3/1.2/1.1 - server 1.0

waf 1.0 선택 시 

tls 높은 버전 사용이 가능함에도 하위 버전을 선택할 때 통신 거절 - fallback 옵션