4d8cff7bd4
If the userland-proxy is running, packets from one bridge network
addressed to the host port are not DNAT'd - so that docker-proxy
can pick them up, and therefore the packet bypasses the network
isolation rules.
Without the userland-proxy, there's no way for a packet from one
bridge network to bypass the network isolation rules. So, in this
case, DNAT is not skipped - and that at-least allows packets
originating from the network that published the port to access
the host port.
Commit 0546d90 improved support for routed mode networks (allowing
nat-mode networks access to containers in routed-mode networks, as
well as just remote access).
That commit changed the "SKIP DNAT" logic, making sure DNAT was
skipped for a routed-mode network if the userland-proxy was enabled
(so, containers in routed mode networks could access ports published
by other networks).
But, it still skipped DNAT for a routed mode network if the userland
proxy was disabled - packets from the routed mode network aimed at
any other network would be dropped by the network isolation rules
anyway, and containers in a routed mode network don't need access to
ports published from that network (because, by definition, there
can't be any).
However, network isolation rules can be worked-around with a rule
in the DOCKER-USER chain, but the SKIP DNAT rule is harder to deal
with.
So, for routed-mode, only skip DNAT if the userland-proxy is
enabled (just like nat-mode networks).
Signed-off-by: Rob Murray <rob.murray@docker.com>
The Moby Project
Moby is an open-source project created by Docker to enable and accelerate software containerization.
It provides a "Lego set" of toolkit components, the framework for assembling them into custom container-based systems, and a place for all container enthusiasts and professionals to experiment and exchange ideas. Components include container build tools, a container registry, orchestration tools, a runtime and more, and these can be used as building blocks in conjunction with other tools and projects.
Principles
Moby is an open project guided by strong principles, aiming to be modular, flexible and without too strong an opinion on user experience. It is open to the community to help set its direction.
- Modular: the project includes lots of components that have well-defined functions and APIs that work together.
- Batteries included but swappable: Moby includes enough components to build fully featured container systems, but its modular architecture ensures that most of the components can be swapped by different implementations.
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The components and tools in the Moby Project are initially the open source components that Docker and the community have built for the Docker Project. New projects can be added if they fit with the community goals. Docker is committed to using Moby as the upstream for the Docker Product. However, other projects are also encouraged to use Moby as an upstream, and to reuse the components in diverse ways, and all these uses will be treated in the same way. External maintainers and contributors are welcomed.
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Moby is licensed under the Apache License, Version 2.0. See LICENSE for the full license text.