## Container on a user-defined network, with a published port, no userland proxy

Running the daemon with the userland proxy disabled then, as before, adding a network running a container with a mapped port, equivalent to:

    dockerd --userland-proxy=false
	docker network create \
	  -o com.docker.network.bridge.name=bridge1 \
	  --subnet 192.0.2.0/24 --gateway 192.0.2.1 bridge1
	docker run --network bridge1 -p 8080:80 --name c1 busybox

The filter table is the same as with the userland proxy enabled.

<details>
<summary>Filter table</summary>

    Chain INPUT (policy ACCEPT 0 packets, 0 bytes)
    num   pkts bytes target     prot opt in     out     source               destination         
    
    Chain FORWARD (policy ACCEPT 0 packets, 0 bytes)
    num   pkts bytes target     prot opt in     out     source               destination         
    1        0     0 DOCKER-USER  0    --  *      *       0.0.0.0/0            0.0.0.0/0           
    2        0     0 DOCKER-FORWARD  0    --  *      *       0.0.0.0/0            0.0.0.0/0           
    
    Chain OUTPUT (policy ACCEPT 0 packets, 0 bytes)
    num   pkts bytes target     prot opt in     out     source               destination         
    
    Chain DOCKER (2 references)
    num   pkts bytes target     prot opt in     out     source               destination         
    1        0     0 ACCEPT     6    --  !bridge1 bridge1  0.0.0.0/0            192.0.2.2            tcp dpt:80
    2        0     0 DROP       0    --  !docker0 docker0  0.0.0.0/0            0.0.0.0/0           
    3        0     0 DROP       0    --  !bridge1 bridge1  0.0.0.0/0            0.0.0.0/0           
    
    Chain DOCKER-BRIDGE (1 references)
    num   pkts bytes target     prot opt in     out     source               destination         
    1        0     0 DOCKER     0    --  *      docker0  0.0.0.0/0            0.0.0.0/0           
    2        0     0 DOCKER     0    --  *      bridge1  0.0.0.0/0            0.0.0.0/0           
    
    Chain DOCKER-CT (1 references)
    num   pkts bytes target     prot opt in     out     source               destination         
    1        0     0 ACCEPT     0    --  *      docker0  0.0.0.0/0            0.0.0.0/0            ctstate RELATED,ESTABLISHED
    2        0     0 ACCEPT     0    --  *      bridge1  0.0.0.0/0            0.0.0.0/0            ctstate RELATED,ESTABLISHED
    
    Chain DOCKER-FORWARD (1 references)
    num   pkts bytes target     prot opt in     out     source               destination         
    1        0     0 DOCKER-CT  0    --  *      *       0.0.0.0/0            0.0.0.0/0           
    2        0     0 DOCKER-ISOLATION-STAGE-1  0    --  *      *       0.0.0.0/0            0.0.0.0/0           
    3        0     0 DOCKER-BRIDGE  0    --  *      *       0.0.0.0/0            0.0.0.0/0           
    4        0     0 ACCEPT     0    --  docker0 *       0.0.0.0/0            0.0.0.0/0           
    5        0     0 ACCEPT     0    --  bridge1 *       0.0.0.0/0            0.0.0.0/0           
    
    Chain DOCKER-ISOLATION-STAGE-1 (1 references)
    num   pkts bytes target     prot opt in     out     source               destination         
    1        0     0 DOCKER-ISOLATION-STAGE-2  0    --  docker0 !docker0  0.0.0.0/0            0.0.0.0/0           
    2        0     0 DOCKER-ISOLATION-STAGE-2  0    --  bridge1 !bridge1  0.0.0.0/0            0.0.0.0/0           
    
    Chain DOCKER-ISOLATION-STAGE-2 (2 references)
    num   pkts bytes target     prot opt in     out     source               destination         
    1        0     0 DROP       0    --  *      bridge1  0.0.0.0/0            0.0.0.0/0           
    2        0     0 DROP       0    --  *      docker0  0.0.0.0/0            0.0.0.0/0           
    
    Chain DOCKER-USER (1 references)
    num   pkts bytes target     prot opt in     out     source               destination         
    1        0     0 RETURN     0    --  *      *       0.0.0.0/0            0.0.0.0/0           
    

    -P INPUT ACCEPT
    -P FORWARD ACCEPT
    -P OUTPUT ACCEPT
    -N DOCKER
    -N DOCKER-BRIDGE
    -N DOCKER-CT
    -N DOCKER-FORWARD
    -N DOCKER-ISOLATION-STAGE-1
    -N DOCKER-ISOLATION-STAGE-2
    -N DOCKER-USER
    -A FORWARD -j DOCKER-USER
    -A FORWARD -j DOCKER-FORWARD
    -A DOCKER -d 192.0.2.2/32 ! -i bridge1 -o bridge1 -p tcp -m tcp --dport 80 -j ACCEPT
    -A DOCKER ! -i docker0 -o docker0 -j DROP
    -A DOCKER ! -i bridge1 -o bridge1 -j DROP
    -A DOCKER-BRIDGE -o docker0 -j DOCKER
    -A DOCKER-BRIDGE -o bridge1 -j DOCKER
    -A DOCKER-CT -o docker0 -m conntrack --ctstate RELATED,ESTABLISHED -j ACCEPT
    -A DOCKER-CT -o bridge1 -m conntrack --ctstate RELATED,ESTABLISHED -j ACCEPT
    -A DOCKER-FORWARD -j DOCKER-CT
    -A DOCKER-FORWARD -j DOCKER-ISOLATION-STAGE-1
    -A DOCKER-FORWARD -j DOCKER-BRIDGE
    -A DOCKER-FORWARD -i docker0 -j ACCEPT
    -A DOCKER-FORWARD -i bridge1 -j ACCEPT
    -A DOCKER-ISOLATION-STAGE-1 -i docker0 ! -o docker0 -j DOCKER-ISOLATION-STAGE-2
    -A DOCKER-ISOLATION-STAGE-1 -i bridge1 ! -o bridge1 -j DOCKER-ISOLATION-STAGE-2
    -A DOCKER-ISOLATION-STAGE-2 -o bridge1 -j DROP
    -A DOCKER-ISOLATION-STAGE-2 -o docker0 -j DROP
    -A DOCKER-USER -j RETURN
    

</details>

The nat table is:

    Chain PREROUTING (policy ACCEPT 0 packets, 0 bytes)
    num   pkts bytes target     prot opt in     out     source               destination         
    1        0     0 DOCKER     0    --  *      *       0.0.0.0/0            0.0.0.0/0            ADDRTYPE match dst-type LOCAL
    
    Chain INPUT (policy ACCEPT 0 packets, 0 bytes)
    num   pkts bytes target     prot opt in     out     source               destination         
    
    Chain OUTPUT (policy ACCEPT 0 packets, 0 bytes)
    num   pkts bytes target     prot opt in     out     source               destination         
    1        0     0 DOCKER     0    --  *      *       0.0.0.0/0            0.0.0.0/0            ADDRTYPE match dst-type LOCAL
    
    Chain POSTROUTING (policy ACCEPT 0 packets, 0 bytes)
    num   pkts bytes target     prot opt in     out     source               destination         
    1        0     0 MASQUERADE  0    --  *      bridge1  0.0.0.0/0            0.0.0.0/0            ADDRTYPE match src-type LOCAL
    2        0     0 MASQUERADE  0    --  *      !bridge1  192.0.2.0/24         0.0.0.0/0           
    3        0     0 MASQUERADE  0    --  *      docker0  0.0.0.0/0            0.0.0.0/0            ADDRTYPE match src-type LOCAL
    4        0     0 MASQUERADE  0    --  *      !docker0  172.17.0.0/16        0.0.0.0/0           
    5        0     0 MASQUERADE  6    --  *      *       192.0.2.2            192.0.2.2            tcp dpt:80
    
    Chain DOCKER (2 references)
    num   pkts bytes target     prot opt in     out     source               destination         
    1        0     0 DNAT       6    --  *      *       0.0.0.0/0            0.0.0.0/0            tcp dpt:8080 to:192.0.2.2:80
    
    
<details>
<summary>iptables commands</summary>

    -P PREROUTING ACCEPT
    -P INPUT ACCEPT
    -P OUTPUT ACCEPT
    -P POSTROUTING ACCEPT
    -N DOCKER
    -A PREROUTING -m addrtype --dst-type LOCAL -j DOCKER
    -A OUTPUT -m addrtype --dst-type LOCAL -j DOCKER
    -A POSTROUTING -o bridge1 -m addrtype --src-type LOCAL -j MASQUERADE
    -A POSTROUTING -s 192.0.2.0/24 ! -o bridge1 -j MASQUERADE
    -A POSTROUTING -o docker0 -m addrtype --src-type LOCAL -j MASQUERADE
    -A POSTROUTING -s 172.17.0.0/16 ! -o docker0 -j MASQUERADE
    -A POSTROUTING -s 192.0.2.2/32 -d 192.0.2.2/32 -p tcp -m tcp --dport 80 -j MASQUERADE
    -A DOCKER -p tcp -m tcp --dport 8080 -j DNAT --to-destination 192.0.2.2:80
    

</details>

Differences from [running with the proxy][0] are:

  - The jump from the OUTPUT chain to DOCKER happens even for loopback addresses.
    [ProgramChain][1].
  - The "SKIP DNAT" RETURN rule for packets routed to the bridge is omitted from
    the DOCKER chain [setupIPTablesInternal][2].
  - A MASQUERADE rule is added for packets sent from the container to one of its
    own published ports on the host.
  - A MASQUERADE rule for packets from a LOCAL source address is included in
    POSTROUTING [setupIPTablesInternal][3].
  - In the DOCKER chain's DNAT rule, there's no destination bridge [setPerPortNAT][4].

[0]: usernet-portmap.md
[1]: https://github.com/moby/moby/blob/333cfa640239153477bf635a8131734d0e9d099d/libnetwork/drivers/bridge/setup_ip_tables_linux.go#L302
[2]: https://github.com/moby/moby/blob/333cfa640239153477bf635a8131734d0e9d099d/libnetwork/drivers/bridge/setup_ip_tables_linux.go#L293
[3]: https://github.com/moby/moby/blob/333cfa640239153477bf635a8131734d0e9d099d/libnetwork/drivers/bridge/setup_ip_tables_linux.go#L302
[4]: https://github.com/moby/moby/blob/675c2ac2db93e38bb9c5a6615d4155a969535fd9/libnetwork/drivers/bridge/port_mapping_linux.go#L772
