Manually Configuring your Modem
Network attacks that deny access to a network device are called DoS attacks.
DoS attacks are aimed at devices and networks with a connection to the Internet. Their goal is not to steal information, but to disable a device or network so users no longer have access to network resources.
The Modem protects against DoS attacks including: Ping of Death (Ping flood) attack, SYN flood attack, IP fragment attack (Teardrop Attack),
Note: The firewall does not significantly affect system performance, so we advise enabling the prevention features to protect your network.
Parameter | Defaults | Description |
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Enable SPI | Yes | The Intrusion Detection feature of |
and Anti- |
| the VoIP Modem limits the access |
DoS firewall |
| of incoming traffic at the WAN port. |
protection |
| When the Stateful Packet Inspection |
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| (SPI) feature is turned on, all incoming |
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| packets are blocked except those |
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| types marked with a check in the |
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| Stateful Packet Inspection section at |
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| the top of the screen. |
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Manually Configuring your Modem
Stateful Packet |
| This option allows you to select |
Inspection |
| different application types that are |
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| using dynamic port numbers. If you |
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| wish to use Stateful Packet Inspection |
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| (SPI) for blocking packets, click on the |
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| Yes radio button in the “Enable SPI and |
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| |
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| then check the inspection type that you |
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| need, such as Packet Fragmentation, |
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| TCP Connection, UDP Session, FTP |
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| Service, H.323 Service, and TFTP |
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| Service. It is called a “Stateful” packet |
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| inspection because it examines the |
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| contents of the packet to determine |
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| the state of the communication; i.e., |
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| it ensures that the stated destination |
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| computer has previously requested the |
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| current communication. This is a way |
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| of ensuring that all communications are |
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| initiated by the recipient computer and |
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| are taking place only with sources that |
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| are known and trusted from previous |
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| interactions. In addition to being more |
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| rigorous in their inspection of packets, |
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| stateful inspection firewalls also |
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| close off ports until a connection to |
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| the specific port is requested. When |
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| particular types of traffic are checked, |
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| only the particular type of traffic |
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| initiated from the internal LAN will be |
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| allowed. For example, if the user only |
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| checks FTP Service in the Stateful |
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| Packet Inspection section, all incoming |
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| traffic will be blocked except for FTP |
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| connections initiated from the local |
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| LAN. |
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Discard Ping |
| Prevents a ping on the Modem’s WAN |
from WAN |
| port from being routed to the network. |
Discard |
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