D-Link NetDefendOS User Manual page 119

IP Rules and Policies for Outgoing Ping Messages
When the ICMP ping message is outgoing from NetDefendOS, it does not require any IP rules or
IP policies to allow the traffic since NetDefendOS is always trusted. In the NetDefendOS event
message logs, an outgoing ping will generate a conn_open and conn_close log event using the
Stock_Allow_All_Rule. The source interface will always be the core interface (meaning
NetDefendOS itself ).
IP Rules and Policies for Incoming Ping Messages
Any ping messages that are incoming require an allowing IP rule or IP policy for NetDefendOS to
respond and these should have the associated Service object set to be the predefined service
ping-inbound. An example IP rule for ping messages arriving on the wan interface would be the
following:
Action Source
Interface
Allow wan
Using the -verbose Option
The -verbose option is recommended to get the maximum amount of information from ping
usage. For example:
gw-world:/> ping 10.6.58.10 -verbose
Sending 1 4-byte ICMP ping to 10.6.58.10 from 192.168.3.20
... using route "192.168.3.20 via lan, gw (Iface IP)" in PBR table "main"
ICMP Reply from 192.168.3.20
Ping Results: Sent: 1, Received:1, Avg RTT: 10.0 ms
Here, the IPv4 address 192.168.3.20 is the IP address of the Ethernet interface on the firewall from
which the ping is sent. The output shows the route lookup that was performed to find the correct
interface.
When packet simulation is performed with the -scrif option (discussed later), the -verbose option
is required in order to show the rules that are triggered.
Testing TCP and UDP Connectivity
ICMP messages are neither UDP or TCP but are considered to be their own third category of IP
traffic. However, the NetDefendOS ping command has the ability to send a messages to test
either TCP or UDP connectivity.
To send as TCP, the -port option is used along with the -tcp option. Successful connectivity then
results in a 3-way TCP handshake taking place with the destination host. For example:
gw-world:/> ping 10.6.58.10 -port=80 -tcp -verbose
Sending 0-byte TCP ping to 10.6.58.10:80 from 192.168.3.20:41207
using PBR table "main"
... using route "10.6.10.0/24 via aux, no gw" in PBR table "main"
TCP Reply from 10.6.58.10:80 to 192.168.3.20:41207 seq=0
time=>10 ms TTL=128
TCP Reply from 10.6.58.10:80 to 192.168.3.20:41207 seq=0
time=>10 ms TTL=128
TCP Ping Results:
Source
Network
all-nets
seq=0 time=<10 ms
Sent: 1, RST/ACKs Received:1, Loss: 0%, Avg RTT: 10.0 ms
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Chapter 2: Management and Maintenance
Destination Destination
Interface Network
core wan_ip
TTL=255
Service
ping-inbound
SYN+ACK
ACK