| 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. |