diff --git a/.gitlab-ci.yml b/.gitlab-ci.yml
index 5edeeb98ad79d2f3cf4bc5ef8d13484ad28a2610..131e54a2c62b21cfa3c2dd9bb930afd8c1b49638 100644
--- a/.gitlab-ci.yml
+++ b/.gitlab-ci.yml
@@ -3,6 +3,9 @@ stages:
   - package
   - deploy
 
+.centos-7:
+  tags: [ linux, docker ]
+  image: git.imp.fu-berlin.de:5000/bioroboticslab/robofish/docker:centos-7
 
 .ubuntu-18.04:
   tags: [ linux, docker ]
@@ -36,6 +39,16 @@ stages:
     expire_in: 1 day
   script: ./.gitlab-ci.py build
 
+build centos-7:
+  extends: .centos-7
+  <<: *build
+  variables:
+    <<: [ *release ]
+  before_script:
+    - ./.gitlab-ci.py prepare
+      --dependency biotracker-interfaces bioroboticslab/biotracker/interfaces master 'package centos-7'
+      --dependency biotracker-utility    bioroboticslab/biotracker/utility    master 'package centos-7'
+
 build ubuntu-18.04:
   extends: .ubuntu-18.04
   <<: *build
@@ -66,6 +79,12 @@ build windows-1809:
     expire_in: 1 week
   script: ./.gitlab-ci.py package
 
+package centos-7:
+  extends: .centos-7
+  dependencies:
+    - build centos-7
+  <<: *package
+
 package ubuntu-18.04:
   extends: .ubuntu-18.04
   dependencies:
diff --git a/Src/Model/Network/TcpListener.cpp b/Src/Model/Network/TcpListener.cpp
index 0a04c53e8aa16117a47200580a6444ada286c816..4f7613600de6782dce2f6ea26c8de30bb655cacd 100644
--- a/Src/Model/Network/TcpListener.cpp
+++ b/Src/Model/Network/TcpListener.cpp
@@ -59,7 +59,7 @@ std::string TcpListener::sendPositions(
 	}
 	str << "end\n";
 
-	//std::cout << str.str() << std::endl;
+	std::cout << str.str() << std::endl;
 
 #ifdef SAVETRACKINGPACKAGES
 	_trackingInfoOutputFile4Simulation << str.str();