Docker Setup for centos 7

Hello I am new to docker and am trying to setup docker on a centos 7 environment. I have installed docker using https://docs.docker.com/install/linux/docker-ce/centos/ and then tried to get a site running using this https://docs.docker.com/engine/examples/dotnetcore/#build-and-run-the-docker-image. I have tried to do wget on locahost and the docker ip on those ports to no avail.

This is what i have executed:

docker build -t aspnetapp .

docker run -it -d --name myapp aspnetapp

this is the docker file

FROM microsoft/dotnet:2.1-aspnetcore-runtime AS base
WORKDIR /app
EXPOSE 64928
EXPOSE 44340

FROM microsoft/dotnet:2.1-sdk AS build

COPY .  /app
WORKDIR /app
RUN dotnet restore "TestDocker.csproj"

FROM build AS publish
RUN dotnet publish "TestDocker.csproj" -c Release -o /app

FROM base AS final

COPY --from=publish /app .
ENTRYPOINT ["dotnet", "TestDocker.dll"]

This builds and runs perfectly

[root@local testSite]# docker ps
CONTAINER ID        IMAGE               COMMAND                  CREATED             STATUS              PORTS                  NAMES
b6044951aa7d        aspnetapp           "dotnet TestDocker.d…"   45 minutes ago      Up 45 minutes       44340/tcp, 64928/tcp   myapp

Firewall D:

[root@local testdocker]# firewall-cmd --list-all
public (active)
  target: default
  icmp-block-inversion: no
  interfaces: enp9s0
  sources:
  services: ssh dhcpv6-client http https
  ports: 44340/tcp 64928/tcp  443/tcp 80/tcp
  protocols:
  masquerade: no
  forward-ports:
  source-ports:
  icmp-blocks:
  rich rules:

I thought I would be able to access it straight from the browser but I have had no luck. Even if there are instructions for this somewhere could someone point me in that direction.

Could this be the issue

Dec 12 14:40:58 local.office firewalld[2591]: WARNING: COMMAND_FAILED: '/usr/sbin/iptables -w2 -t nat -C POSTROUTING -p tcp -s 172.17.0.2 -d 172.17.0.2 --dport 64928 -j MASQUERADE' failed: iptables: No chain/target/match by that name.
Dec 12 14:40:58 local.office firewalld[2591]: WARNING: COMMAND_FAILED: '/usr/sbin/iptables -w2 -t nat -C DOCKER -p tcp -d 0/0 --dport 80 -j DNAT --to-destination 172.17.0.2:64928 ! -i docker0' failed: iptables: No chain/target/match by that name.
Dec 12 14:42:36 local.office firewalld[2591]: WARNING: COMMAND_FAILED: '/usr/sbin/iptables -w2 -t filter -C DOCKER ! -i docker0 -o docker0 -p tcp -d 172.17.0.2 --dport 64928 -j ACCEPT' failed: iptables: Bad rule (does a matching rule exist in that chain?).
Dec 12 14:42:36 local.office firewalld[2591]: WARNING: COMMAND_FAILED: '/usr/sbin/iptables -w2 -t nat -C POSTROUTING -p tcp -s 172.17.0.2 -d 172.17.0.2 --dport 64928 -j MASQUERADE' failed: iptables: No chain/target/match by that name.
Dec 12 14:43:18 local.office firewalld[2591]: WARNING: COMMAND_FAILED: '/usr/sbin/iptables -w2 -t nat -C DOCKER -p tcp -d 0/0 --dport 64928 -j DNAT --to-destination 172.17.0.2:64928 ! -i docker0' failed: iptables: No chain/target/match by that name.

Solution

Although FirewallD is the default firewall programme for CentOS 7, it is deactivated by default on a new CentOS 7 server. Therefore, let's activate it and add the required network ports. You may try to add the ports in your firewall application using below.

firewall-cmd --add-port=64928/tcp --permanent

firewall-cmd --add-port=44340/tcp --permanent

You can check with your Docker firewall rules once as those are the rules set before the default firewall management tools on the OS.

iptables -L -v -n -t nat --line-numbers

You can check those using above command.