Netopia 4553 User Reference Manual page 147

Select Input Filter 1 and press Return. In the Change Input Filter 1 screen, set the Destination Port information
as shown below.
Enabled:
Forward:
Source IP Address:
Source IP Address Mask:
Dest. IP Address:
Dest. IP Address Mask:
Protocol Type:
Source Port Compare...
Source Port ID:
Dest. Port Compare...
Dest. Port ID:
Established TCP Conns. Only:
Select Input Filter 2 and press Return. In the Change Input Filter 2 screen, set the Protocol Type to allow GRE
as shown below.
Enabled:
Forward:
Source IP Address:
Source IP Address Mask:
Dest. IP Address:
Dest. IP Address Mask:
Protocol Type:
Change Input Filter 1
Yes
Yes
0.0.0.0
0.0.0.0
0.0.0.0
0.0.0.0
TCP
No Compare
0
Equal
1723
No
Change Input Filter 2
Yes
Yes
0.0.0.0
0.0.0.0
0.0.0.0
0.0.0.0
GRE
Virtual Private Networks (VPNs) 10-147