keepalive disable msie6;

[locojohn]

Конечно, ну за исключением виртуальных
хостов и подключаемых конф. файлов - 
уверяю вас, там нет директивы keepalive_disable
и нет никаких ссылок на значение "msie6".

#user nginx nginx;
user www www;
worker_processes 4;
worker_rlimit_nofile 131072;
worker_cpu_affinity 0001 0010 0100 1000;

error_log /var/log/nginx/error_log warn;

events {
	worker_connections 65536;
	use epoll;
#	debug_connection 217.24.65.183;
}

http {
	include /etc/nginx/mime.types;
	default_type application/octet-stream;

	log_format main
		'$remote_addr - $remote_user [$time_local] '
		'"$request" $status $bytes_sent '
		'"$http_referer" "$http_user_agent" '
		'"$gzip_ratio" $request_time';

	client_header_timeout 10m;
	client_body_timeout 10m;
	send_timeout 10m;

	client_max_body_size 700m;
	connection_pool_size 256;
	client_body_buffer_size 1024k;
	client_header_buffer_size 8k;
	large_client_header_buffers 4 8k;
	request_pool_size 4k;
	
	proxy_buffering on;
	proxy_buffer_size 4k;
	proxy_buffers 4096 4k;
	
	open_file_cache max=2000 inactive=60s;
	open_file_cache_valid 60;
	open_log_file_cache max=1000 inactive=60s valid=1m;
	
	geoip_country /usr/share/GeoIP/GeoIP.dat; # the country IP database
	geoip_city    /usr/share/GeoIP/GeoLiteCity.dat; # the city IP
database

	gzip on;
	gzip_min_length 1100;
	gzip_buffers 4 8k;
	gzip_types text/plain text/css application/x-javascript text/xml
application/xml application/xml+rss text/javascript;

	output_buffers 1 128k;
	postpone_output 1460;

	aio on;
	directio 512;
	sendfile on;
	tcp_nopush on;
	tcp_nodelay on;

	keepalive_timeout 75 20;
#	keepalive_disable msie6;

	ignore_invalid_headers on;
	server_name_in_redirect on;
	
	fastcgi_pass_request_headers on;
	fastcgi_intercept_errors on;
	fastcgi_buffer_size 32k;
	fastcgi_buffers 8 16k;
	fastcgi_read_timeout 300;
	fastcgi_send_timeout 300;

	# use the map module to correctly set $script_url variable
	map $uri $script_url {
         ~^(?<script_filename>.+\.(php|html))(?<path_info>.+)$
$path_info;
         ~^(?<script_filename>.+\.(php|html))$
$script_filename;
	}
	
	index index.html;
	
	upstream phpfarm {
	 server unix:/var/run/fastcgi/php-fpm-1.sock weight=100 max_fails=3
fail_timeout=5;
	 server unix:/var/run/fastcgi/php-fpm-2.sock weight=100 max_fails=3
fail_timeout=5;
	 server unix:/var/run/fastcgi/php-fpm-3.sock weight=100 max_fails=3
fail_timeout=5;
       }

       # upload progress
       upload_progress uploads 1m;
       upload_progress_content_type "application/json";
       upload_progress_json_output;


### virtual host configuration

  [...]

}

Posted at Nginx Forum: http://forum.nginx.org/read.php?21,218659,218662#msg-218662