I install this image: Ubuntu Docker 17.12.0~ce on 16.04, in ssh i run sudo ufw status verbose and get:

Status: active
Logging: on (low)
Default: deny (incoming), allow (outgoing), allow (routed)
New profiles: skip

To                         Action      From
--                         ------      ----
22                         LIMIT IN    Anywhere                  
2375/tcp                   ALLOW IN    Anywhere                  
2376/tcp                   ALLOW IN    Anywhere                  
22 (v6)                    LIMIT IN    Anywhere (v6)             
2375/tcp (v6)              ALLOW IN    Anywhere (v6)             
2376/tcp (v6)              ALLOW IN    Anywhere (v6)       

Ok to test that this firewall works i run some docker image on port 80 (nginx proxy):

sudo docker run -d -p 80:80 -e ENABLE_IPV6=true -v /var/run/docker.sock:/tmp/docker.sock:ro jwilder/nginx-proxy:alpine

Theoretically I should be not able to connect to por 80 but when I go to browser and type droplet IP i see nginx screen - this means that firewall ufw NOT WORKS at all (!!!).

When I install pure Ubuntu image (without docker) and manually instal ufw and docker I get similar error.

So what I should do to make UFW firewall works ?

I try this:

sudo ufw default deny incoming
sudo ufw default allow outgoing
sudo ufw enable

But doesn't work :(

Above error is very easy to reproduce - may be the ubuntu images are broken?