scanning and error

[andrius]

Hello,

My server listen on 0.0.0.0 for public requests. It's in demo mode and does not protected by any firewall. Network scanners sometimes try to send some flood and I am getting errors like this:

[2016-12-10 19:45:48.489] INFO  Celluloid: Listening on http://0.0.0.0:8080
route_request(request): #<Reel::Request POST http://t19.proxy-checks.com/favicon.ico HTTP/1.1 @headers={"Host"=>"t19.proxy-checks.com", "Proxy-Connection"=>"Keep-Alive", "Accept"=>"text/html,application/xhtml+xml,application/xml;q=0.9,image/webp,*/*;q=0.8", "User-Agent"=>"Mozilla/4.0 (compatible; MSIE 7.0; Windows NT 6.0; SLCC1; .NET CLR 2.0.50727; Media Center PC 5.0; .NET CLR 3.5.21022; .NET CLR 3.5.30729; .NET CLR 3.0.30618)", "Accept-Language"=>"en-US;q=0.6,en;q=0.4", "Content-Length"=>"0", "Pragma"=>"no-cache"}>
95.25.97.222 - - [10/Dec/2016:19:45:50 +0800] "POST /favicon.ico " 404 - 0.0009
route_request(request): #<Reel::Request GET / HTTP/1.0 @headers={"User-Agent"=>"masscan/1.0 (https://github.com/robertdavidgraham/masscan)", "Accept"=>"*/*"}>
212.92.127.143 - - [10/Dec/2016:19:55:29 +0800] "GET / " 404 - 0.0020
route_request(request): #<Reel::Request CONNECT mx-tw.mail.gm0.yahoodns.net:25 HTTP/1.0 @headers={}>
[2016-12-10 20:10:05.663] ERROR Celluloid: Actor crashed!
NoMethodError: undefined method `[]' for nil:NilClass
        /usr/lib/ruby/gems/2.3.0/gems/rack-2.0.1/lib/rack/mock.rb:90:in `env_for'
        /usr/lib/ruby/gems/2.3.0/gems/reel-rack-0.2.3/lib/reel/rack/server.rb:47:in `route_request'
        /usr/lib/ruby/gems/2.3.0/gems/reel-rack-0.2.3/lib/reel/rack/server.rb:29:in `block in on_connection'

It happening in line 46 at /usr/lib/ruby/gems/2.3.0/gems/reel-rack-0.2.3/lib/reel/rack/server.rb

And I have added puts command before that print out request, it is:

route_request(request): #<Reel::Request GET / HTTP/1.0 @headers={"User-Agent"=>"masscan/1.0 (https://github.com/robertdavidgraham/masscan)", "Accept"=>"*/*"}>

Question: is that normal? If so, how could I fix those error logs?
I understand that I can firewall system, but in production mode it would have public access. I do have authentication already, there is grape API behind – but that won't help against scanning