peek
When a peek rule matches during step1, Squid proceeds to step2 where it parses the TLS Client Hello and extracts SNI (if any). When a peek rule matches during step 2, Squid proceeds to step3 where it parses the TLS Server Hello and extracts server certificate while preserving the possibility of splicing the client and server connections; peeking at the server certificate usually precludes future bumping (see Limitations).
splice
Become a TCP tunnel without decoding the connection. The client and the server exchange data as if there is no proxy in between.
bump
Establish a TLS connection with the server (using client SNI, if any) and establish a TLS connection with the client (using a mimicked server certificate). However, this is not what actually happens right now if a bump rule matches during step1.
terminate
Close client and server connections.
關閉client與server的連線
stare
When a stare rule matches during step1, Squid proceeds to step2 where it parses the TLS Client Hello and extracts SNI (if any). When a stare rule matches during step2, Squid proceeds to step3 where it parses the TLS Server Hello and extracts server certificate while preserving the possibility of bumping the client and server connections; staring at the server certificate usually precludes future splicing (see Limitations).
情境劇stare and bump
stare在step3時將所有連線設定為splice，也就是一般的TCP Tunnel連線，若現在要與某一網站進行bump，bump設定將至於stare與splice之間，如此即可達到指定網站bump的功能。
Reference
Squid, SquidGuard, and Lightsquid on pfSense 2.4
SslBump Peek and Splice
Squid configuration directive ssl_bump