/conf/tomcat-users.xml

<role rolename="manager-gui"/>
<user username="username" password="password" roles="manager-gui"/>

sudo systemctl restart tomcat

<Valve className="org.apache.catalina.valves.RemoteAddrValve" allow="127.d+.d+.d+|::1|0:0:0:0:0:0:0:1 />