To adjust resources used by your firewall service, you can change the sizing parameters in the General Firewall Configuration (CONFIGURATION > Configuration Tree > Box > Infrastructure Services) section of the Barracuda NextGen Firewall F-Series. After changing general firewall configuration settings, perform a Firmware Restart (CONTROL > Box) for the changes to take effect. Default values vary depending on the model.
Maximum Number of Connections
Max Session Slots – Set the maximum number of session slots allowed. The amount of memory consumed by the firewall is updated when this value is changed and displayed in the Firewall Memory [MB] field. (When set to the default value, the firewall service will consumer about 150 MB RAM.)
Max UDP (%) – Defines the percentage of the Max Session Slots allowed to be UDP sessions.
Max Echo (%) – Defines the percentage of the Max Session Slots allowed to be ICMP sessions.
Max Other (%) – Defines the percentage of the Max Session Slots allowed to be an IP protocol type, except TCP, UDP, or ICMP.
Firewall Memory [MB] – Displays the estimated memory requirement according to the current firewall configuration settings. If the value exceeds 200 MB, an additional bootloader parameter may be required. On i686-based F-Series Firewalls with more than 768 MB RAM requiring additional vmalloc space to satisfy the increased memory demand of non-default firewall settings, we recommend to increase the vmalloc area in steps of 128 MB, starting at 384 MB. For more information, see How to Configure the Bootloader .
Global Limits 1
Max SIP Calls – Set the maximum number of concurrent SIP calls that can be handled by the legacy SIP firewall plugin.
Max SIP Transactions – Set the maximum amount of SIP transactions that can be handled by the legacy SIP firewall plugin.
Max SIP Media – Define the maximum amount of SIP Media (RTP) connections allowed for the legacy SIP firewall plugin. The inactivity timeout for the media connections can be configured by setting the Balanced Timeout for the service object.
Max DNS Entries – Defines the maximum number of DNS queries that may be triggered by use of network objects containing hostnames. 75% of the queries are reserved for the forwarding firewall and 25% for the host firewall. Network objects used in both forwarding and host firewall rulesets will trigger two DNS queries and be counted twice.
- Max Acceptors – Maximum number of pending accepts for inbound rules. An acceptor is a dynamic implicit rule that is generated by plugins handling dynamic connection requests. The FTP protocol, for example, uses a data connection beside the control connection on TCP port 21 to perform the actual file transfer. By analyzing the FTP protocol, the firewall knows when such data connections occur and creates an acceptor to allow the corresponding data transfer session.
- Max Pending Inbounds – Maximum number of pending TCP inbound requests. This parameter only comes into effect when the TCP accept policy is set to inbound for the access rule.
- Max BARPs – Defines the maximum number of bridging ARPs allowed. A bridging ARP entry (BARP) stores the information that specifies which bridge interface corresponds to a certain MAC address. Additionally, associated IP addresses are stored along with the BARP entry. Modifying this value may be useful for large bridging setups.
- Max Plugins – Maximum number of rules using plugins.
- Dyn Service Names (RPC) – Maximum number of dynamic service name entries.
Global Limits 2
- Inbound Mode Threshold (%) – Threshold of pending accepts, at which point the firewall switches to the inbound TCP accept policy to guard against SYN flooding attacks.
- SYN Cookie High Watermark (%) – Percentage (of maximum pending inbounds) of pending inbound accepts to switch to SYN cookie usage for enhanced SYN flooding protection.
- SYN Cookie Low Watermark (%) – Percentage (of maximum pending inbounds) of pending inbound accepts to go back to ordinary SYN handling.
- Max Dynamic Rules – Maximum number of dynamically activated rules.
- Max Multiple Redirect IPs – Maximum number of IP addresses in rules with multiple redirect target IPs.
- Max SOCKS Workers – Maximum number of available SOCKS workers when the Generic TCP proxy mode is enabled.
Source-Based Session Limits
Max Local-On Session/Src – Maximum number of sessions per source IP address. Cannot be set to more than Max Session Slots.
Max Local-In UDP/Src – Maximum number of UDP sessions per source IP address.
Max Local-In Echo/Src – Maximum number of ICMP Echo sessions per source IP.
Max Local-In Other/Src – Maximum number of sessions for all other IP protocols (not TCP, UDP, ICMP) per source IP address.
- Max Pending Local Accepts/Src – Maximum number of pending accepts per source IP address.
The firewall history stores connection information for troubleshooting purposes. You can configure how many and how long connections are stored in the General Firewall Configuration settings. Use the Advanced View to configure these settings.
- Max. Access Entries – Determines the size of the visualization caches.
- Max. Block Entries – Determines the maximum number of block entries.
- Max. Drop Entries – Determines the maximum number of drop entries.
- Max. Fail Entries – Determines the maximum number of fail entries.
- Max. Scan Entries – Determines the maximum number of scan entries.
- DNS Resolve IPs – Setting this parameter to yes will resolve IPs to hostnames on the firewall history. This may cause excessive load on the DNS servers.
- Rule Matching Policy – Selects the way in which a rule lookup is performed.
- Kernel space – linear lookup – adequate for small rulesets.
- Kernel space – tree lookup – preferred option for large rulesets with hundreds of rules.
As a rule of thumb, for about 1000 session/s the Kernel space should be enabled for better firewall performance. Additionally, if many firewall objects (> 200) are used, the Kernel space - tree option is recommended.
- Rule Change Behavior – This setting only applies to the forwarding firewall and not to the host firewall, because the host firewall generally does not allow re-evaluation of a session upon a rule-change. The setting specifies whether an existing connection is terminated (Terminate-on-change or not (Keep-on-change) if the ruleset changes and the session is no longer allowed by the new ruleset.
- No Rule Update Time Range – This option allows defining a time range during which access rules may not be updated. Use international time format. For example, to disallow rule update from 14:00 through 22:00, insert
Default TCP Policy
- Syn Flood Protection – Defines the default behavior of the firewall with regard to the TCP three-way handshake.
Outbound – Passes on the SYN to the target address.
- Inbound – The firewall completes the handshake and only then performs a handshake with the actual target. This helps to protect the target from SYN flood attacks. Disabling will cause an overhead in packet transmission, but may speed up interactive protocols like SSH.
- Nagle Algorithm – This parameter enables/disables the Nagle algorithm. This option is only available when using stream forwarding.
- Perform TCP Sequence Check – This parameter enables/disables TCP sequence checks.You can select one of the following options:
- All Packets
Raw TCP Mode Policy
- RAW TCP Idle Timeout – Defines the idle timeout value in seconds for RAW TCP mode.
- RAW TCP Timeout Policy – Defines the timeout policy that will be used for RAW TCP mode.
- Use-global-timeouts – Sets the timeout value that has been configured in the previous sections.
- Use-tcp-timeouts – Uses the timeout values from standard TCP set in the matching rule.
Default Anti-Spoofing Policy
ARP Reverse Route Check – Setting this parameter to Yes causes answers to ARP requests to be checked if source IP and interface match.
Reverse Interface Policy – The options of this parameter specify whether requests and replies must use the same (outgoing) interface (same-interface or not (interface-may-change).
Port Scan Policy
- Port Scan Threshold – When the number of blocked requests exceed the threshold, a port scan is detected and a port scan event is triggered. To not generate an event, see How to Configure Basic, Severity, and Notification Settings for Events .
- Port Scan Detection Interval – Detection interval in seconds to check for not allowed activity. In combination with the parameter Port Scan Threshold, it defines the condition when to report a port scan.
Session Creation CPU Limit (%) – (advanced) Reserves a specific amount of CPU resources for the Barracuda OS to prevent the firewall from becoming unmanageable in case of a high amount of concurrent sessions being initiated. Barracuda Networks recommends to keep the Default value.
Validate TCP Checksum – (advanced) Enables an additional TCP packet consistency check. This will reduce performance.
- Validate UDP Checksum – (advanced) Enables an additional UDP packet consistency check. This will reduce performance.
- Parallel Shaping Tree Evaluation – (advanced)
- Disabled – Disables this option.
- Enabled – Improves shaping tree evaluation.
- Enable-MultiQueue-Only – Enables this feature only for shaping trees built on top of interfaces with multiple hardware-queues or with RPS enabled.
High Availability Related Policies
Allow Active-Active Mode – (advanced) Active-Active firewall operation mode has to be enabled in preparation for operation of multiple active firewalls on one box with a load balancer connected upstream.
Enable Session Sync – (advanced) All currently established sessions will be synced to the HA partner to improve failover performance.
Log Synced Sessions – (advanced) This setting determines logging of access cache sessions, which have been synchronized between HA partners. Set to No to disable logging.
Generically Forwarded Networks – (advanced) Traffic between networks inserted into this field will be excluded from firewall monitoring and will be forwarded without source and destination differentiation, even if no forwarding firewall is installed.
When TCP stream reassembly and HTML parsing are set to auto the operating system enables or disables these features to best match your current configuration and performance.
- TCP Stream Reassembly for IPS – Reassembles the TCP stream before scanning for vulnerabilities.
- HTML Parsing for IPS – Toggles HTML obfuscation detection. If this setting is changed, you must reboot for the changes to take effect.
- IPS Scan Mode – Select the scanning mode for IPS. You must reboot for the changes to take effect.
- Auto – The firewall automatically chooses the best suited mode.
- Fast Scan – Scan select packets to improve performance and throughput.
- Full Scan – Scan all packets.
VPN Rate Limit (Mbps) – Limits how fast VPN traffic is encrypted and decrypted. Change this value if you experience excessive CPU load in an environment with many VPN tunnels. The value 0 does not impose any restriction.
- Enable Assembler Ciphers – Using the assembler implementation for AES/SHA/MD5 increases VPN performance significantly.
- Enable Intel AVX Extensions – Enables or disables the usage of Intel’s AVX extension (also valid on AMD processors).
- Enable VIA PadLock – Enables or disables the usage of VIAs PadLock Security Engine.
Enable Cavium – Enable or disable Cavium crypto acceleration cards.
Globally clear DF bit – Clears the DF bit for each ipv4 packet routed through a VPN tunnel. For more information on MTU, see Routing.
Resource Failure Policy
- Out of Memory Policy – An out of memory condition may disable protocol and application detection. As a consequence, all deeper analysis will be disabled as well.
- Fail-Open – Select to continue forwarding.
- Fail-Close – Select to terminate the affected sessions.
Url Categorization (URL Filter)
- Max. Cache Entries – The maximum number of entries in the kernel cache. 0 is auto selection depending on RAM size.
- Categorization Timeout [s] – Set the maximum timeout to wait for categorization response.
- Cache Entry Expiration [s] – After the configured time, the cached entries category will be updated.
- Cache Entry Expiration (no cat.) [s] – After the specified time in seconds, the cached entries' category, with category 'not categorized' will be updated.
- Cache Entry Expiration (err cat.) [s] – After the specified time in seconds, the cached entries' category, with category 'assigning error' will be updated.
Application and Port Protocol Detection
- Enable Port Detection – Set to yes to use deep packet inspection to enforce the used protocol on a port. For more information, see How to Configure Port Protocol Protection
Application Detection Destination Tracking
- Enable Destination Tracking – Set to no unless specifically instructed otherwise by Barracuda technical support.
Supervisory Control and Data Acquisition (SCADA)
SCADA Protocol Detection – Enable to detect SCADA protocols.
Disabled – Detection is disabled.
Enable without Parsing Log – Detected SCADA protocols are included in the Firewall Activity log.
Enable with Parsing Log – Enabled with detailed logs (box/SCADA/parsing).
Audit and Reporting
- Generate Dashboard Information – Enable/disable the firewall dashboard.
- Generate Monitor Information – Enable the firewall monitor.
- Maximum Storage Size [MB] – Specify the storage size in megabytes to be used for monitor information data. A value of 0 enables automatic assignment based on the device.
- Statistics for Host Firewall – This option enables statistics for connections passing through the host firewall.
- Generate Protocol Statistics – If enabled, protocol and P2P-specific statistics are created and listed within the statistics viewer under .../server/BOX/proto-stat/...
- Use username if available – If set to yes, usernames are used for statistics, if available. Otherwise, the source IP address is used.
- Generate Events – Enable/Disable event generation.
- Event Data – Use this section to selectively enable or disable event generation.
Application Control Logging – Select the global policy for Application Control 2.0 logging.
Activity Log Mode – Configure whether the Firewall Activity logs use key-value pairs or only log the values. Default: only values are logged.
- Log Level – Decides whether log messages are accumulated to avoid too large log files.
- Cumulative Interval [s] – Interval (in sec) for which cumulative logging is activated for either matching or similar log entries.
- Cumulative Maximum – Maximum of similar log entries to start cumulative logging.
- Generate Audit Log – Enable the generation of structured firewall audit data that can be stored locally and/or forwarded. If enabled, the 'Audit Log' tab of the firewall UI will get populated with data.
- Audit Log Data – Use this section to selectively enable or disable audit log generation.
- Log ICMP Packets – Select the log policy for ICMP packets.
- Log-All – Log all ICMP packets except type ECHO.
- Log-Unexpected – Log all ICMP packets except ECHO and UNREACHABLE.
- Log-None – Disable ICMP logging.
- Allow Threat Log Processing – Allow other processes to access threat log information for further processing.
- Enable IPFIX/Netflow – Internet Protocol Flow Information Export (IPFIX, RFC 3917) is based on NetFlow Version 9. You can use this setting to stream the FW audit log via IPFIX. Note that using this also requires an adjustment of Audit Delivery within section Audit Log Data to Send-IPFIX.
- Enable intermediate reports – Enable sending of intermediate reports with delta counters. (Use the IPFIX reporting interval [m] option to determine how often intermediate reports are sent.)
- IPFIX reporting interval [m] – Interval in minutes between two intermediate IPFIX flow reports for each active flow.
- IPFIX Template – If set to Extended, includes additional information such as delta counters, to the IPFIX export. If your collector does not support reverse flows, select Uniflow templates, these templates will duplicate the traffic against the collector.
- Collectors – Add external IPFIX collectors.
- Settings – Click Set/Edit to configure connection tracing settings.
Out of Session (OOS) Packet Policy
- Interfaces to Send TCP RST – The firewall sends TCP RST packets to these network interfaces if it detects packets not belonging to an active session. This is useful to avoid timeouts on certain servers.
- IPV4 Networks to Send TCP RST – The firewall sends TCP RST packets to these IPv4 networks if it detects packets not belonging to an active session.
- IPV6 Networks to Send TCP RST – The firewall sends TCP RST packets to these IPv6 networks if it detects packets not belonging to an active session.