Add Access rules for Snort inspection
Create Access rules to select traffic for Snort inspection.
You can use the following matching criteria in Access rules that select traffic for Snort inspection:
- Source and destination IP addresses, networks, and interfacesNote: If you use Logical Interfaces that have overlapping IP address spaces as matching criteria in Access rules that select traffic for Snort inspection, traffic might not match Snort rules as intended.
- Service elements that match based on the port that the traffic usesNote: We do not recommend using services that match based on the payload of connections, such as Network Applications, URL Categories, or URL List Applications, in Access rules that select traffic for Snort inspection.
For more details about the product and how to configure features, click Help or press F1.
Steps
Select Rule Action Options dialog box (Allow)
Use this dialog box to override and specify the options for the Allow action in the Engine Policy.
Option | Definition |
---|---|
General tab | |
Forward Traffic To (Engine/VPN role only) |
Select a Host or Proxy Server element to forward traffic to. Click Select to select an element.
There are similar restrictions than when configuring destination NAT rules. For example, if you forward to a host, the IP address range in the Destination field of the rule must be an equivalent size to the IP address range of the host. If you forward traffic to a proxy or a host, the NAT rules are ignored. If you use NAT rules, you must configure forwarding in NAT rules rather than Access rules. |
Forced Next Hop (Engine/VPN role only) |
Enter an IP Address or select a Host to force forward the matched traffic to the preferred destination. Click Select to select a host. The IP Address can be an
IPv4 or IPv6.
Note:
|
Option | Definition |
---|---|
General tab | |
SD-WAN section | |
SD-WAN Action (Engine/VPN role only) |
To forward traffic into a VPN, select from the following options:
To apply the action to VPN client traffic in any mobile VPN, select Any Mobile VPN (IPv4 only). |
Option | Definition |
---|---|
General | |
Inspection Options | |
Deep Inspection | Selects traffic that matches this rule for checking against the Inspection Policy referenced by this policy. Traffic is inspected as the Protocol that is attached to the
Service element in this rule.
|
Network Application Latency Monitoring | To decide whether to monitor network health and latency of connections and applications.
|
File Filtering | Selects traffic that matches this rule for checking against the File Filtering Policy referenced by this policy.
|
Anti-Spam | The Anti-Spam feature is no longer supported in Secure SD-WAN version 6.2.0 and higher. |
Decryption | Defines whether traffic that matches the rule is decrypted for TLS inspection or by the SSM HTTP Proxy (Secure SD-WAN Engines in the Engine/VPN role
only).
|
Option | Definition |
---|---|
General tab | |
Snort Options section | |
Snort | Selects traffic that matches this rule for Snort
inspection.
|
Option | Definition |
---|---|
Advanced tab | |
Connection Options section | |
Connection Tracking Mode |
|
Idle Timeout | The timeout (in seconds) after which inactive connections are closed. This timeout concerns only idle connections. Connections are not cut because of timeouts while the hosts are
still communicating. If you enter a timeout, this value overrides the setting defined in the Secure SD-WAN Engine properties. CAUTION: Do not set long timeouts for many connections. Each connection that is kept active consumes resources on the Secure SD-WAN Engine.
Setting excessive timeouts for many connections can lead to serious performance problems. Generally, the idle timeout is not more than a few minutes.
|
Synchronize Connections | Defines whether connection information is synchronized between Secure SD-WAN Engine cluster nodes. Disabling connection synchronization reduces
the traffic volume on the active heartbeat interface, but it also prevents transparent failover of connections to other nodes.
|
Enforce TCP MSS
(IPv4 Only) |
Defines whether TCP MSS is enforced. Headers are not included in the maximum segment size (MSS) value; MSS concerns only the payload of the packet. Usually, network equipment sends
packets at the Ethernet-standard maximum transmission unit (MTU) size of 1500 (including both payload and headers).
|
Minimum | If a TCP packet has an MSS value smaller than the minimum you set here, the packet is dropped. The smaller the data content is, the less efficient the communications become due to the fixed-size headers. Limiting the minimum size can help alleviate certain types of network attacks. Typically, the value you enter is not larger than the default minimum TCP Maximum Segment Size (536). |
Maximum | If a TCP packet has an MSS value larger than the maximum, the Secure SD-WAN Engine overwrites the packet’s MSS with the maximum value you set here. Setting the maximum MSS size might be necessary to prevent fragmentation. Typically, the value you enter is lower than the standard Ethernet MTU (1500), taking the packet headers that are added to the MSS into account. |
Option | Definition |
---|---|
Advanced tab | |
DoS Protection Options section | |
Concurrent Connection Limit per Source IP and Concurrent Connection Limit per Destination IP |
Enter the maximum number of open connections from or to each IP address at any one time. These limits are enforced by rules that have their Action set to Allow or Continue, and when the SD-WAN Action in an Action option is Apply SD-WAN, Enforce SD-WAN, or Forward. Be careful to apply the concurrent connection limits correctly for the types of communication that this rule handles to avoid cutting off connections unnecessarily. |
Action | The Action that is applied to new connections if the limit is reached.
|
Rate-Based DoS Protection | Defines whether rate-based DoS protection is applied to traffic that matches the rule.
|
Scan Detection | Defines whether scan detection is applied to traffic that matches the rule.
|
Select Rule Action Options dialog box (Continue)
Use this dialog box to override and specify the options for the Continue action.
Option | Definition |
---|---|
General tab | |
Forward Traffic To (Engine/VPN role only) |
Select a Host or Proxy Server element to forward traffic to. Click Select to select an element.
There are similar restrictions than when configuring destination NAT rules. For example, if you forward to a host, the IP address range in the Destination field of the rule must be an equivalent size to the IP address range of the host. If you forward traffic to a proxy or a host, the NAT rules are ignored. If you use NAT rules, you must configure forwarding in NAT rules rather than Access rules. |
Option | Definition |
---|---|
General tab | |
SD-WAN section | |
SD-WAN Action (Engine/VPN role only) |
To forward traffic into a VPN, select from the following options:
To apply the action to VPN client traffic in any mobile VPN, select Any Mobile VPN (IPv4 only). |
Option | Definition |
---|---|
General tab | |
Inspection Options section | |
Deep Inspection | Selects traffic that matches this rule for checking against the Inspection Policy referenced by this policy. Traffic is inspected as the Protocol that is attached to the Service
element in this rule.
|
File Filtering | Selects traffic that matches this rule for checking against the File Filtering Policy referenced by this policy.
|
Anti-Spam | The Anti-Spam feature is no longer supported in Secure SD-WAN version 6.2.0 and higher. |
Decryption | Defines whether traffic that matches the rule is decrypted for TLS inspection or by the SSM HTTP Proxy (Secure SD-WAN Engines in the Engine/VPN
role only).
|
Option | Definition |
---|---|
General tab | |
Snort Options section | |
Snort | Selects traffic that matches this rule for Snort
inspection.
|
Option | Definition |
---|---|
Advanced tab | |
Connection Options section | |
Connection Tracking Mode |
|
Idle Timeout | The timeout (in seconds) after which inactive connections are closed. This timeout concerns only idle connections. Connections are not cut because of timeouts while the hosts are
still communicating. If you enter a timeout, this value overrides the setting defined in the Secure SD-WAN Engine properties. CAUTION: Do not set long timeouts for many connections. Each connection that is kept active consumes resources on the Secure SD-WAN Engine.
Setting excessive timeouts for many connections can lead to serious performance problems. Generally, the idle timeout is not more than a few minutes.
|
Synchronize Connections | Defines whether connection information is synchronized between Secure SD-WAN Engine cluster nodes. Disabling connection synchronization reduces
the traffic volume on the active heartbeat interface, but it also prevents transparent failover of connections to other nodes.
|
Enforce TCP MSS
(IPv4 Only) |
Defines whether TCP MSS is enforced. Headers are not included in the maximum segment size (MSS) value; MSS concerns only the payload of the packet. Usually, network equipment sends
packets at the Ethernet-standard maximum transmission unit (MTU) size of 1500 (including both payload and headers).
|
Minimum | If a TCP packet has an MSS value smaller than the minimum you set here, the packet is dropped. The smaller the data content is, the less efficient the communications become due to the fixed-size headers. Limiting the minimum size can help alleviate certain types of network attacks. Typically, the value you enter is not larger than the default minimum TCP Maximum Segment Size (536). |
Maximum | If a TCP packet has an MSS value larger than the maximum, the Secure SD-WAN Engine overwrites the packet’s MSS with the maximum value you set here. Setting the maximum MSS size might be necessary to prevent fragmentation. Typically, the value you enter is lower than the standard Ethernet MTU (1500), taking the packet headers that are added to the MSS into account. |
Option | Definition |
---|---|
Advanced tab | |
DoS Protection Options section | |
Concurrent Connection Limit per Source IP and Concurrent Connection Limit per Destination IP |
Enter the maximum number of open connections from or to each IP address at any one time. These limits are enforced by rules that have their Action set to Allow or Continue, and when the SD-WAN Action in an Action option is Apply SD-WAN, Enforce SD-WAN, or Forward. Be careful to apply the concurrent connection limits correctly for the types of communication that this rule handles to avoid cutting off connections unnecessarily. |
Action | The Action that is applied to new connections if the limit is reached.
|
Rate-Based DoS Protection | Defines whether rate-based DoS protection is applied to traffic that matches the rule.
|
Scan Detection | Defines whether scan detection is applied to traffic that matches the rule.
|
Option | Definition |
---|---|
Response tab | |
Override Settings Inherited from Continue Rule(s) | When selected, overrides settings defined in Continue rules higher up in the policy. |
User Response
(HTTP only) |
Specifies the automatic response that is shown to the end user when a connection is discarded. Click Select to select an element. You can use the default response or create a custom response. User Responses are not supported on Virtual Secure SD-WAN Engines. |