1 This module matches the parameters in Authentication header of IPsec packets. 2 .TP 3 [\fB!\fP] \fB\-\-ahspi\fP \fIspi\fP[\fB:\fP\fIspi\fP] 4 Matches SPI. 5 .TP 6 [\fB!\fP] \fB\-\-ahlen\fP \fIlength\fP 7 Total length of this header in octets. 8 .TP 9 \fB\-\-ahres\fP 10 Matches if the reserved field is filled with zero. 11