Configuring TCP SYN Flood Attack Screen
This topic describes how to configure detection of a TCP SYN flood attack.
A SYN flood occurs when a host is so overwhelmed by SYN segments initiating incomplete connection requests that it can no longer process legitimate connection requests.
To enable detection of a TCP SYN flood attack:
- Configure interfaces and assign an IP address to interfaces.user@host# set interfaces xe-0/0/1 unit 0 family inet address 192.0.2.0/24user@host# set interfaces xe-0/0/3 unit 0 family inet address 198.51.100.0/24
- Configure security zones trustZone and untrustZone and assign interfaces to them.user@host# set security zones security-zone trustZone host-inbound-traffic system-services alluser@host# set security zones security-zone trustZone host-inbound-traffic protocols alluser@host# set security zones security-zone trustZone interfaces xe-0/0/1.0user@host# set security zones security-zone untrustZone host-inbound-traffic system-services alluser@host# set security zones security-zone untrustZone host-inbound-traffic protocols alluser@host# set security zones security-zone untrustZone interfaces xe-0/0/3.0
- Configure security policies from untrustZone to trustZone.user@host# set security policies from-zone untrustZone to-zone trustZone policy policy1 match source-address anyuser@host# set security policies from-zone untrustZone to-zone trustZone policy policy1 match destination-address anyuser@host# set security policies from-zone untrustZone to-zone trustZone policy policy1 match application anyuser@host# set security policies from-zone untrustZone to-zone trustZone policy policy1 then permituser@host# set security policies default-policy deny-all
- Configure security screens and attach them to untrustZone.user@host# set security screen ids-option untrustScreen tcp syn-flooduser@host# set security screen ids-option untrustScreen alarm-without-dropuser@host# set security zones security-zone untrustZone screen untrustScreen
- Configure syslog.user@host# set system syslog file syslog any anyuser@host# set system syslog file syslog archive size 10000000user@host# set system syslog file syslog explicit-priorityuser@host# set system syslog file syslog structured-datauser@host# set security policies from-zone untrustZone to-zone trustZone policy policy1 then log session-inituser@host# set security policies from-zone untrustZone to-zone trustZone policy policy1 then log session-close
- Commit the configuration.user@host# commit