Damans227 commented on code in PR #13795:
URL: https://github.com/apache/cloudstack/pull/13795#discussion_r3974968240
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systemvm/debian/opt/cloud/bin/setup/common.sh:
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@@ -573,10 +573,42 @@ setup_dnsmasq() {
fi
}
+enable_ipv6_link_local() {
+ local eth=$1
+ log_it "Enabling IPv6 link-local on interface $eth"
+ # Generate the link-local address with EUI-64 based on the MAC address so
+ # the address can be calculated by the Management Server
+ sysctl -w net.ipv6.conf.${eth}.addr_gen_mode=0
+ # Only a link-local address is wanted, no SLAAC/RA configuration
+ sysctl -w net.ipv6.conf.${eth}.accept_ra=0
+ sysctl -w net.ipv6.conf.${eth}.autoconf=0
+ sysctl -w net.ipv6.conf.${eth}.disable_ipv6=0
Review Comment:
tested this on a lab and it gets undone a few seconds later, so the feature
doesnt survive a boot.
this sets the runtime value only. the template ships
`net.ipv6.conf.all.disable_ipv6 = 1` in `/etc/sysctl.conf`, and
`bootstrap.sh:104` runs `sysctl -p` after `setup_sshd`. boot order on the ssvm:
```
00:43:15 Configuring sshd
00:43:15 Enabling IPv6 link-local on interface eth0
00:43:17 Interface eth0 has IPv6 link-local address fe80::c00:a9ff:fefe:cadc
00:43:17 Configuring sshd to also listen on fe80::c00:a9ff:fefe:cadc%eth0
00:43:19 Executing cloud-early-config
00:43:20 Bootstrapping systemvm appliance <- sysctl -p in here
```
end state, address gone and sshd only on v4:
```
$ ip -6 addr show dev eth0
(nothing)
$ sysctl -n net.ipv6.conf.eth0.disable_ipv6
1
$ ss -tln | grep 3922
LISTEN 0 128 169.254.202.220:3922 0.0.0.0:*
```
showed it directly on the vm:
```
$ sysctl -qw net.ipv6.conf.eth0.disable_ipv6=0
$ ip -6 addr show dev eth0 scope link
inet6 fe80::c00:a9ff:fefe:cadc/64 scope link
$ sysctl -p
$ ip -6 addr show dev eth0 scope link
(gone)
```
so `listSystemVms` shows a `linklocalip6` that nothing answers on. ping6 and
ssh to it both time out from the host.
the design is fine by the way, once i left ipv6 on and restarted sshd it
worked end to end over `fe80::...%cloud0` on 3922.
can we clear the persistent one too? `common.sh:126-129` already does that
for `net.ipv6.conf.all.disable_ipv6` including rewriting sysctl.conf.
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