nginx: ignore some requests without proper Host he

问题:

In nginx to drop connection I can return 444, however there is a problem with that IMO. It seems that 444 doesn't silently drop the connection, but actually closes it gracefully, as a result tools that all these spammers use will rapidly retry the request:

149.56.28.239 - - [22/Sep/2016:20:33:18 +0200] "PROPFIND /webdav/ HTTP/1.1" 444 0 "-" "WEBDAV Client"
149.56.28.239 - - [22/Sep/2016:20:33:18 +0200] "PROPFIND /webdav/ HTTP/1.1" 444 0 "-" "WEBDAV Client"

is there a way to abort tcp (not gracefully as if my server was suddenly unplugged from the net) so that on the requester end it would continue waiting? Are there any drawbacks/problems with that and is that possible with nginx?

To drop requests without Host header in nginx you use the following config:

server {
    listen      80;
    return      444;
}

Is there a way to handle some of these requests for example if requested url matches some regex?