mppe +H -M +S -L -D -C what each character mean.
根据Microsoft Point-To-Point Encryption (MPPE) Protocol的rfc3078文件中第2节Configuration Option Format:
H:使用stateless模式(this indicates that the sender wishes to negotiate the use of stateless mode)
M:使用56bit密钥(this indicates the desire of the sender to negotiate the use of 56-bit session keys)
S:使用128bit密钥(this indicates the desire of the sender to negotiate the use of 128-bit session keys)
L:使用40bit密钥(this indicates the desire of the sender to negotiate the use of 40-bit session keys)
D:已过期(The ‘D‘ bit is obsolete)
C:供MPPC使用(The ‘C‘ bit is used by MPPC)
参考:
https://www.ietf.org/rfc/rfc3078.txt
原文:http://my.oschina.net/u/1382972/blog/337923