No IPv6 Web GUI access if LAN interface is set to 'Track Interface'

[maurice-w]

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Describe the bug

If a LAN interface is tracking a WAN interface and the Web GUI is configured to only listen on this LAN interface, the Web GUI is inaccessible via IPv6.

To Reproduce

Steps to reproduce the behavior:

1. Make sure the WAN and LAN interfaces have default settings (WAN: DHCPv4 + DHCPv6 with prefix delegation, LAN: Static IPv4 + 'Track Interface' IPv6).
2. Go to 'System: Settings: Administration', set the 'Web GUI Listen Interfaces' to 'LAN', save and reboot.
3. See error: The Web GUI is not accessible via the LAN IPv6 address.
4. Access the Web GUI via the LAN IPv4 address, go to 'System: Diagnostics: Services' and restart the webgui service.
5. See result: The Web GUI is now accessible via the LAN IPv6 address.

Expected behavior

The Web GUI should be accessible via IPv6 without having to manually restart the service after a reboot.

Relevant log files

Excerpt from /var/etc/lighty-webConfigurator.conf after a reboot:

## bind to port (default: 80)
server.bind  = "127.0.0.1"
server.port  = 80
$SERVER["socket"] == "127.0.0.1:80" {
}
$SERVER["socket"] == "[::1]:80" {
}
$SERVER["socket"] == "192.168.1.1:80" {
}

After webgui service restart:

## bind to port (default: 80)
server.bind  = "127.0.0.1"
server.port  = 80
$SERVER["socket"] == "127.0.0.1:80" {
}
$SERVER["socket"] == "[::1]:80" {
}
$SERVER["socket"] == "192.168.1.1:80" {
}
$SERVER["socket"] == "[2001:db8:1234:5600:215:5dff:fed2:761b]:80" {
}

Additional context

It works when not selecting specific listen interfaces ($SERVER["socket"] == "[::]:80").

Environment

OPNsense 23.1.a_102 (amd64, OpenSSL)
Hyper-V Gen2 Ver10.0

[maurice-w]

Same issue for SSH. After a reboot, the tracking LAN interface's IPv6 address is missing from /usr/local/etc/ssh/sshd_config and IPv6 SSH access doesn't work. Restarting the openssh service temporarily fixes this.

Historical context seems to be #1347.

[fichtner]

I'm happy to try and tackle this while working on #5933, but it might not be a pretty outcome.

Cheers,
Franco

[fichtner]

@maurice-w I was a bit surprised to see a newwanip event for web GUI already implemented. The issue here is that newwanip is not called for LAN, only for WAN... 745d46c could work, but is not the best thing structurally as webgui (and other things) may be loaded multiple times.

[fichtner]

RC1 seems to behave for the time being. Nothing to do and do another iteration if necessary.