SYN Defender (sim synatk, sim6 synatk, asg synatk)
A SYN flood attack occurs when a host, typically with a forged address, sends a flood of TCP/SYN packets. Each of these packets is handled as a connection request, which causes the server to create a "half-open connection". This occurs because the gateway sends a TCP/SYN-ACK (Acknowledge) packet, and waits for a response packet, which does not arrive. These half-open connections eventually exceed the maximum available connections, which causes a denial of service condition. SYN defender protects the gateway by dropping excessive half-open connections.
You can use these commands to:
- Configure a defense against an IPv4 SYN Flood attack (
sim synatk). - Configure a defense against an IPv6 SYN Flood attack (
sim6 synatk). - Monitor the system during attacks and normal system operation (
asg synatk).
This protection works with Performance Pack.
Syntax
> sim synatk [-e] [-d] [-m] [-g] [-t <threshold>] [-a] [monitor] [monitor -v]
> sim6 synatk [-e] [-d] [-m] [-g] [-t <threshold>] [-a] [monitor] [monitor -v]
> asg synatk [-b <sgm_ids>] [-4 | -6]
> sim6 synatk -a
Parameter
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Description
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-e
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Enable SYN defender. This make the system engage when it recognizes an attack on an external interface. External interfaces are defined in SmartDashboard. Internal interfaces are always in monitor mode.
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-d
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Disable SYN Defender.
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-m
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Set monitor mode. SYN defender only sends a log when it recognizes an attack.
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-g
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Enforce on all interfaces.
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-t <threshold>
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Set the SYN Defender threshold number of half-opened connections.
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-a
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Use configuration from: $PPKDIR/conf/synatk.conf
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monitor
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Show the attack monitoring tool.
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monitor -v
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Show the attack monitoring tool with extra (verbose) information.
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-b <sgm_ids>
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Show the status for specified SGMs and Chassis.
Works with SGMs and/or Chassis as specified by <sgm_ids>.
<sgm_ids> can be:
- No <sgm_ids> specified or
all shows all SGMs and Chassis - One SGM
- A comma-separated list of SGMs (
1_1,1_4) - A range of SGMs (
1_1-1_4) - One Chassis (
Chassis1 or Chassis2) - The active Chassis (
chassis_active)
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-6
|
Shows the IPv6 status only.
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-4
|
Shows the IPv4 status only.
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