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Table Of Contents
- Contents
- About This Document
- Network Security
- TCP SYN attacks
- IP TCP syn-proxy
- Granular application of syn-proxy feature
- Syn-def
- No response to non-SYN first packet of a TCP flow
- Prioritizing management traffic
- Peak BP utilization with TRAP
- Transaction Rate Limit (TRL)
- Understanding transaction rate limit
- Configuring transaction rate limit
- Configuring the maximum number of rules
- Saving a TRL configuration
- Transaction rate limit command reference
- Global TRL
- TRL plus security ACL-ID
- security acl-id
- Transaction rate limit hold-down value
- Displaying TRL rules statistics
- Displaying TRL rules in a policy
- Displaying IP address with held down traffic
- Refusing new connections from a specified IP address
- HTTP TRL
- Overview of HTTP TRL
- Configuring HTTP TRL
- Displaying HTTP TRL
- Display all HTTP TRL policies
- Display HTTP TRL policy from index
- Display HTTP TRL policy client
- Display HTTP TRL policy starting from index
- Display HTTP TRL policy matching a regular expression
- Display HTTP TRL policy client index (MP)
- Display HTTP TRL policy client index (BP)
- Display HTTP TRL policy for all client entries (BP)
- Downloading an HTTP TRL policy through TFTP
- HTTP TRL policy commands
- Logging for DoS Attacks
- Maximum connections
- clear statistics dos-attack
- Maximum concurrent connection limit per client
- Firewall load balancing enhancements
- Syn-cookie threshhold trap
- Service port attack protection in hardware
- Traffic segmentation
- DNS attack protection
- Access Control List
- How ServerIron processes ACLs
- Default ACL action
- Types of IP ACLs
- ACL IDs and entries
- ACL entries and the Layer 4 CAM
- Configuring numbered and named ACLs
- Modifying ACLs
- Displaying a list of ACL entries
- Applying an ACLs to interfaces
- ACL logging
- Dropping all fragments that exactly match a flow-based ACL
- Enabling ACL filtering of fragmented packets
- Enabling hardware filtering for packets denied by flow-based ACLs
- Enabling strict TCP or UDP mode for flow-based ACLs
- ACLs and ICMP
- Using ACLs and NAT on the same interface (flow-based ACLs)
- Displaying ACL bindings
- Troubleshooting rule-based ACLs
- IPv6 Access Control Lists
- Network Address Translation
- Syn-Proxy and DoS Protection
- Understanding Syn-Proxy
- Configuring Syn-Proxy
- DDoS protection
- Configuring a security filter
- Configuring a Generic Rule
- Configuring a rule for common attack types
- Configuring a rule for ip-option attack types
- Configuring a rule for icmp-type options
- Configuring a rule for IPv6 ICMP types
- Configuring a rule for IPv6 ext header types
- Binding the filter to an interface
- Clearing DOS attack statistics
- Clearing all DDOS Filter & Attack Counters
- Logging for DoS attacks
- Displaying security filter statistics
- Address-sweep and port-scan logging
- Secure Socket Layer (SSL) Acceleration
- SSL overview
- SSL acceleration on the ServerIron ADX
- Configuring SSL on a ServerIron ADX
- Basic SSL profile configuration
- Advanced SSL profile configuration
- Configuring Real and Virtual Servers for SSL Termination and Proxy Mode
- Configuration Examples for SSL Termination and Proxy Modes
- SSL debug and troubleshooting commands
- Displaying socket information
114 ServerIron ADX Security Guide
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Configuring Syn-Proxy
5
If you want your ServerIron ADX to behave more like a JetCore-based ServerIron device, you can use
any of the following three workarounds:
1. Enable syn-proxy on the server interface
2. Enable ip nat
3. Enable "server security-on-vip-only".
Configuring Syn-Proxy
This section contains the following sections:
• “Enabling SYN-Proxy” on page 114
• “Setting Attack-Rate-Threshold” on page 115
• “Setting SYN-Ack-Window-Size” on page 115
• “Setting Reset-Using-Client-MAC” on page 115
• “Retransmitting TCP SYNs” on page 116
NOTE
Syn-Proxy is not supported for IPv6 for releases earlier than 12.2.0.
NOTE
In a syn-proxy configuration for a local client, if an ARP entry for the client is not stored, the first TCP
connection may need to retransmit none-syn packets since it may get dropped until the ServerIron
ADX stores an ARP entry for the client. There will only be a performance impact for the very first
connection.
NOTE
If you use log action inside access-list deny rules, then you cannot combine such an ACL with
hardware-based syn-proxy on the same interface. To do so, you can either remove log action or
disable hardware syn-proxy using the server disable-hw-syn-cookie command. Remember that if you
disable hardware syn-proxy, you will harm syn-proxy performance.
NOTE
DSR is not supported with SYN-proxy and is supported with SYN-def.
Enabling SYN-Proxy
To activate Syn-Proxy, follow these steps:
1. Globally enable Syn-Proxy, using the following command:
ServerIronADX(config)# ip tcp syn-proxy
Syntax: ip tcp syn-proxy
NOTE
The ip tcp syn-proxy command must be executed at the global configuration level. If it is
executed at the interface configuration level it will not take effect.
2. Configure a port and enter the interface configuration mode, using the following commands: