-This module matches the SPIs in AH header of IPSec packets.
+This module matches the parameters in Authentication header of IPsec packets.
.TP
.BR "--ahspi " "[!] \fIspi\fP[:\fIspi\fP]"
+Matches SPI.
+.TP
+.BR "--ahlen " "[!] \fIlength"
+Total length of this header in octets.
+.TP
+.BI "--ahres"
+Matches if the reserved field is filled with zero.