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Bind the port 80 to Java:

Since running as graylog ( Java software) user can’t open ports < 1024, we have to solutions to this:

Allow java open ports < 1024:

First, we need to find the Java bin file:

sudo update-alternatives --config java

The output will look something like the following. In this case, this is what the output will look like with all Java versions installed.

There are 5 choices for the alternative java (providing /usr/bin/java).

  Selection    Path                                            Priority   Status
* 0            /usr/lib/jvm/java-8-openjdk-amd64/jre/bin/java   1081      auto mode
  1            /usr/lib/jvm/java-6-oracle/jre/bin/java          1         manual mode
  2            /usr/lib/jvm/java-7-oracle/jre/bin/java          2         manual mode
  3            /usr/lib/jvm/java-8-openjdk-amd64/jre/bin/java   1081      manual mode
  4            /usr/lib/jvm/java-8-oracle/jre/bin/java          3         manual mode
  5            /usr/lib/jvm/java-9-oracle/bin/java              4         manual mode

Press <enter> to keep the current choice[*], or type selection number:


Note down the Path with star mark * , issue the command:

sudo setcap CAP_NET_BIND_SERVICE=+eip /usr/lib/jvm/java-8-openjdk-amd64/jre/bin/java
Port redirecting:

So the solution is:

sudo iptables -t nat -A PREROUTING -i eth0 -p tcp --dport 80 -j REDIRECT --to-port 9000

or for all interfaces

sudo iptables -t nat -A PREROUTING -p tcp --dport 80 -j REDIRECT --to-port 9000