Suppress Arduino SocketListener messages.

.travis.yml

@@ -1,6 +1,13 @@
 dist: trusty
 before_install:
   - sudo apt-get install -y ninja-build
+  # Arduino IDE adds a lot of noise caused by network traffic, trying to firewall it off
+  - sudo iptables -P INPUT DROP
+  - sudo iptables -P FORWARD DROP
+  - sudo iptables -P OUTPUT ACCEPT
+  - sudo iptables -A INPUT -i lo -j ACCEPT
+  - sudo iptables -A OUTPUT -o lo -j ACCEPT
+  - sudo iptables -A INPUT -m conntrack --ctstate ESTABLISHED,RELATED -j ACCEPT
 script:
   - bash -x test.sh
   - cp Firmware/variants/1_75mm_MK3S-EINSy10a-E3Dv6full.h Firmware/Configuration_prusa.h