[ https://issues.apache.org/jira/browse/CLOUDSTACK-9339?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15594173#comment-15594173 ]
ASF GitHub Bot commented on CLOUDSTACK-9339: -------------------------------------------- Github user murali-reddy commented on the issue: https://github.com/apache/cloudstack/pull/1659 @blueorangutan package > Virtual Routers don't handle Multiple Public Interfaces > ------------------------------------------------------- > > Key: CLOUDSTACK-9339 > URL: https://issues.apache.org/jira/browse/CLOUDSTACK-9339 > Project: CloudStack > Issue Type: Bug > Security Level: Public(Anyone can view this level - this is the > default.) > Components: Virtual Router > Affects Versions: 4.8.0 > Reporter: dsclose > Labels: firewall, nat, router > > There are a series of issues with the way Virtual Routers manage multiple > public interfaces. These are more pronounced on redundant virtual router > setups. I have not attempted to examine these issues in a VPC context. > Outside of a VPC context, however, the following is expected behaviour: > * eth0 connects the router to the guest network. > * In RvR setups, keepalived manages the guests' gateway IP as a virtual IP on > eth0. > * eth1 provides a local link to the hypervisor, allowing Cloudstack to issue > commands to the router. > * eth2 is the routers public interface. By default, a single public IP will > be setup on eth2 along with the necessary iptables and ip rules to source-NAT > guest traffic to that public IP. > * When a public IP address is assigned to the router that is on a separate > subnet to the source-NAT IP, a new interface is configured, such as eth3, and > the IP is assigned to that interface. > * This can result in eth3, eth4, eth5, etc. being created depending upon how > many public subnets the router has to work with. > The above all works. The following, however, is currently not working: > * Public interfaces should be set to DOWN on backup redundant routers. The > master.py script is responsible for setting public interfaces to UP during a > keepalived transition. Currently the check_is_up method of the CsIP class > brings all interfaces UP on both RvR. A proposed fix for this has been > discussed on the mailing list. That fix will leave public interfaces DOWN on > RvR allowing the keepalived transition to control the state of public > interfaces. Issue #1413 includes a commit that contradicts the proposed fix > so it is unclear what the current state of the code should be. > * Newly created interfaces should be set to UP on master redundant routers. > Assuming public interfaces should be default be DOWN on an RvR we need to > accommodate the fact that, as interfaces are created, no keepalived > transition occurs. This means that assigning an IP from a new public subnet > will have no effect (as the interface will be down) until the network is > restarted with a "clean up." > * Public interfaces other than eth2 do not forward traffic. There are two > iptables rules in the FORWARD chain of the filter table created for eth2 that > allow forwarding between eth2 and eth0. Equivalent rules are not created for > other public interfaces so forwarded traffic is dropped. > * Outbound traffic from guest VMs does not honour static-NAT rules. Instead, > outbound traffic is source-NAT'd to the networks default source-NAT IP. New > connections from guests that are destined for public networks are processed > like so: > 1. Traffic is matched against the following rule in the mangle table that > marks the connection with a 0x0: > *mangle > -A PREROUTING -i eth0 -m state --state NEW -j CONNMARK --set-xmark > 0x0/0xffffffff > 2. There are no "ip rule" statements that match a connection marked 0x0, so > the kernel routes the connection via the default gateway. That gateway is on > source-NAT subnet, so the connection is routed out of eth2. > 3. The following iptables rules are then matched in the filter table: > *filter > -A FORWARD -i eth0 -o eth2 -j FW_OUTBOUND > -A FW_OUTBOUND -j FW_EGRESS_RULES > -A FW_EGRESS_RULES -j ACCEPT > 4. Finally, the following rule is matched from the nat table, where the IP > address is the source-NAT IP: > *nat > -A POSTROUTING -o eth2 -j SNAT --to-source 123.4.5.67 > -- This message was sent by Atlassian JIRA (v6.3.4#6332)