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