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The brctl command (from bridge-utils) is an easier dependency than requiring users to setup the bridge themselves. Following [1]. [1]: https://docs.docker.com/articles/networking/#bridge-building
One 'ip link set' call can set all the values we need; there's no need for a separate call for each value. I've shifted the veth1 call to after the route and address, to avoid putting it up before it's fully configured. We have to add the route after putting veth1 up though, to avoid: RTNETLINK answers: Network is unreachable
One less step for the user to handle on their own. We might want to log this change, since it has the potential to create unwanted side-effects if the user has a permissive firewall. If procps (from which we get sysctl) is too burdensome a dependency, we could use: echo 1 > /proc/sys/net/ipv4/ip_forward
Based on [1]. With ACCEPT policies for INPUT, FORWARD, and OUTPUT in the filter table, and PREROUTING, INPUT, OUTPUT, and POSTROUTING in the nat table, this MASQUERADE jump is all we need. With those permissive rules, external hosts can access the containers by adding a route like: # ip route add 10.0.0.0/24 via 192.168.0.2 where 192.168.0.2 is the IP address of the Bocker host. For more restrictive networking, you could be harsher with FORWARD on the Bocker host and use: # iptables -t nat -A PREROUTING ! -i bridge0 -p tcp --dport 80 -j DNAT --to 10.0.0.3:80 # iptables -I FORWARD -d 10.0.0.3 -p tcp --dport 80 -j ACCEPT to forward the Bocker host's port 80 to the 10.0.0.3 container's port 80. [1]: https://github.com/gdm85/docker-fw/blob/d9cee19989ead67e6107740869ba9c13d4ff6096/example-iptables.txt
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wking, do you think this should be merged with 'bocker route' in #23? The idea would be to allow the user to leave existing network configuration undisturbed if necessary. |
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On Thu, Aug 20, 2015 at 05:48:04PM -0700, Chris F Ravenscroft wrote:
This PR shouldn't be doing anything different if bridge0 already For rebasing onto #23, I'm happy to do that if #23 lands first, but |
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If bridge0 doesn't exist, automatically create it, enable IPv4
forwarding, and setup a minimal MASQUERADE rule so the containers can
access the external network. Details in the individual commit
messages.
This grows the script by 7 lines (to 124 lines), but allowing most
users to not bother using brctl and iptables is probably worth it ;).