title: My firewall is blocking network connections from the docker container to outside
body: <p>For me this is a very standard setup, I had a ubuntu machine running docker and ufw as my firewall.</p>
  
  <p>If my firewall is enable the docker instances is unable to connect to outside</p>
  
  <pre><code>$ docker run -i -t ubuntu /bin/bash
  WARNING:  Docker detected local DNS server on resolv.conf. Using default external servers: [8.8.8.8 8.8.4.4]
  root@d300c5f17207:/# apt-get update
  Err http://archive.ubuntu.com precise InRelease
  0% [Connecting to archive.ubuntu.com]
  W: Failed to fetch http://archive.ubuntu.com/ubuntu/dists/precise/InRelease  
  W: Failed to fetch http://archive.ubuntu.com/ubuntu/dists/precise/Release.gpg  Temporary failure resolving 'archive.ubuntu.com'
  W: Some index files failed to download. They have been ignored, or old ones used instead.
  </code></pre>
  
  <p>Here is the ufw log showing the blocked connections from the docker container.</p>
  
  <pre><code>$ sudo tail /var/log/ufw.log
  Jun 30 15:41:56 localhost kernel: [61609.503199] [UFW BLOCK] IN=testbr0 OUT=eth0 PHYSIN=veth8Rj8Nh MAC=fe:ff:ed:42:b0:01:0a:7c:42:7c:a6:72:08:00 SRC=172.16.42.2 DST=8.8.8.8 LEN=64 TOS=0x00 PREC=0x00 TTL=63 ID=14886 DF PROTO=UDP SPT=60192 DPT=53 LEN=44 
  Jun 30 15:42:01 localhost kernel: [61614.500867] [UFW BLOCK] IN=testbr0 OUT=eth0 PHYSIN=veth8Rj8Nh MAC=fe:ff:ed:42:b0:01:0a:7c:42:7c:a6:72:08:00 SRC=172.16.42.2 DST=8.8.4.4 LEN=64 TOS=0x00 PREC=0x00 TTL=63 ID=16137 DF PROTO=UDP SPT=44812 DPT=53 LEN=44 
  Jun 30 15:42:06 localhost kernel: [61619.498516] [UFW BLOCK] IN=testbr0 OUT=eth0 PHYSIN=veth8Rj8Nh MAC=fe:ff:ed:42:b0:01:0a:7c:42:7c:a6:72:08:00 SRC=172.16.42.2 DST=8.8.8.8 LEN=64 TOS=0x00 PREC=0x00 TTL=63 ID=14887 DF PROTO=UDP SPT=60192 DPT=53 LEN=44
  </code></pre>
  
  <p>I had try adding a rule using the ip.</p>
  
  <pre><code>$ sudo ufw allow in from 172.16.42.2
  $ sudo ufw allow out from 172.16.42.2
  </code></pre>
  
  <p>And have no change is still blocked.</p>
  
  <p>How can I esily allow all connections from the container to outside with a ufw rule?</p>