HE863 family AT commands reference guide
80377ST10083a Rev.6 – 2012-11-12
Reproduction forbidden without written authorization from Telit Communications S.p.A.- All Rights Reserved.
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#FRWL - Firewall Setup
IP address mask in the format: xxx.xxx.xxx.xxx
Command returns
OK
result code if successful.
Note: the firewall applies for incoming (listening) connections only.
Firewall general policy is
DROP
, therefore all packets that are not included into an
ACCEPT
chain rule will be silently discarded.
When a packet comes from the IP address
incoming_IP
, the firewall chain rules
will be scanned for matching with the following criteria:
incoming_IP & <net_mask> = <ip_addr> & <net_mask>
If criteria is matched, then the packet is accepted and the rule scan is finished; if
criteria is not matched for any chain the packet is silently dropped.
AT#FRWL?
Read command reports the list of all
ACCEPT
chain rules registered in the
Firewall settings in the format:
#FRWL: <ip_addr>,<net_mask>
#FRWL: <ip_addr>,<net_mask>
….
OK
AT#FRWL=?
Test command returns the allowed values for parameter
<action>.
Example
Let assume we want to accept connections only from our devices which are on the
IP addresses ranging from
197.158.1.1 to 197.158.255.255
We need to add the following chain to the firewall:
AT#FRWL=1,"197.158.1.1","255.255.0.0"
OK
Note
For outgoing connections made with #SKTOP and #SKTD the remote host is
dynamically inserted into the
ACCEPT
chain for all the connection duration.
Therefore the
#FRWL
command shall be used only for defining the
#SKTL
behaviour, deciding which hosts are allowed to connect to the local device.
Rules are not saved in NVM, at startup the rules list will be empty.
3.5.5.1.80.
Maximum TCP Payload Size - #TCPMAXDAT
#TCPMAXDAT – Maximum TCP Payload Size
