HWLoadbalancerCheckErrors

Some Hardware Load-balancers such Cisco's CSS and BigIP Products test the readiness of the backend Machines with SYN-ACK-RST.

This behavior causes a 400 error in nginx.

With the GEO Module  and the if-Statement you can omit these entries:

http { geo $lb  { default     0; 10.1.1.1/32 1;   # LB IPs 10.1.1.2/32 1;  }

# ...

server { # ...   access_log   /path/to/log; error_page 400 /400;

location = /400 { if ($lb) { access_log off; }     return 400; } } }