35 lines
1.5 KiB
Diff
35 lines
1.5 KiB
Diff
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From ed425bdd6fefacb0f06b35fa8f4caedf042dc84d Mon Sep 17 00:00:00 2001
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From: "Cel A. Skeggs" <cela@mit.edu>
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Date: Thu, 1 Feb 2018 17:49:12 -0500
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Subject: [PATCH] backend/udp: Use a /32 prefix for the flannel0 interface
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This avoids the kernel's creation of broadcast routes, which prevent
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communication from the host with the zeroth subnet to containers on any
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other hosts.
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---
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backend/udp/udp_network.go | 10 ++++++++--
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1 file changed, 8 insertions(+), 2 deletions(-)
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diff --git a/backend/udp/udp_network.go b/backend/udp/udp_network.go
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index 1f9752f8..242ebf49 100644
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--- a/backend/udp/udp_network.go
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+++ b/backend/udp/udp_network.go
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@@ -153,9 +153,15 @@ func configureIface(ifname string, ipn ip.IP4Net, mtu int) error {
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return fmt.Errorf("failed to lookup interface %v", ifname)
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}
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- err = netlink.AddrAdd(iface, &netlink.Addr{IPNet: ipn.ToIPNet(), Label: ""})
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+ // Ensure that the device has a /32 address so that no broadcast routes are created.
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+ // This IP is just used as a source address for host to workload traffic (so
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+ // the return path for the traffic has an address on the flannel network to use as the destination)
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+ ipnLocal := ipn
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+ ipnLocal.PrefixLen = 32
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+
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+ err = netlink.AddrAdd(iface, &netlink.Addr{IPNet: ipnLocal.ToIPNet(), Label: ""})
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if err != nil {
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- return fmt.Errorf("failed to add IP address %v to %v: %v", ipn.String(), ifname, err)
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+ return fmt.Errorf("failed to add IP address %v to %v: %v", ipnLocal.String(), ifname, err)
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}
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err = netlink.LinkSetMTU(iface, mtu)
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