N O V A T E L W I R E L E S S T E C H N O L O G I E S L T D .
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A T C o m m a n d S p e c i f i c a t i o n - E x p e d i t e a n d M e r l i n
W i r e l e s s I P M o d e m s
Friends Mode
Description:
In “Friends” mode, the modem can be configured to reject all messages received that do not originate
from a “friendly” IP address. Up to 10 “friendly” IP addresses can be entered. Once a series of “friendly” IP
addresses or ranges have been entered, enabling “Friends” mode will block reception of data except from
IP addresses in the list. If a message arrives that is not from a “friend” and “Friends” mode has been
enabled, the message will be silently discarded.
Format:
ATFM=0
“Friends” mode disabled
ATFM=1
“Friends” mode enabled
ATFM?
Queries the “Friends” mode setting
ATFn=a.b.c.d
Sets entry n in “Friends” list to be IP address a.b.c.d
ATF?
Queries all 10 entries in the “Friends” list.
In the “Friends” list, entries are indexed from 0 so valid entry positions are 0-9.
When defining IP addresses, 255 can be used as a wildcard.
As an example, suppose that you wish to only accept messages from IP 125.125.125.128 and from any IP
in the 210.180.45 subnet. This could be configured with the following commands:
ATF1=125.125.125.128
OK
ATF2=210.180.45.255
OK
ATF?
0=125.125.125.128
1=210.180.45.255
2=0.0.0.0
3=0.0.0.0
4=0.0.0.0
5=0.0.0.0
6=0.0.0.0
7=0.0.0.0
8=0.0.0.0
9=0.0.0.0
OK
ATFM=1
OK
Validity:
This security feature is only available in the TCP and UDP PAD modes, and the AT command mode. This
security feature is NOT available when a PPP or SLIP data mode is used.
The “Friends” mode feature can be configured in both AT mode or Program mode. Modifications to the
“Friends” list are saved immediately, regardless of mode.