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Add IPv6 inside the PPP session and use enp2s0 in the example

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- wan.ipv6.transport = "ppp": IPv6CP in pppd, router advertisements and
  DHCPv6 prefix delegation on the PPP device, DHCPv6 accepted on the PPP
  device, IPv6 MSS clamped to MTU-60. Allowed on a shared single-NIC
  link. A build-time check requires a PPPoE uplink.
- IPv4 MSS clamping now only matches IPv4 packets.
- The example uses the new box's NIC name (enp2s0).

Covered by the onestick VM test (radvd and a minimal DHCPv6-PD
responder as the ISP) and assertion cases.

Co-Authored-By: Claude Sonnet 5.5 <noreply@anthropic.com>
This commit is contained in:
nils
2026-10-28 15:03:57 +01:00
co-authored by Claude Sonnet 5.5
parent b5429ad876
commit 70dddad206
9 changed files with 227 additions and 22 deletions
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modules/router/networking.nix
+31 -4
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@@ -2,6 +2,11 @@
let
cfg = config.router;
v6 = cfg.wan.ipv6.enable;
v6ppp = v6 && cfg.wan.ipv6.transport == "ppp";
# IPv6 on the physical link (not inside the PPP session).
v6native = v6 && !v6ppp;
# The device carrying DHCPv6 / RAs.
v6dev = if v6ppp then cfg.wan.ipv4.interface else cfg.wan.interface;
pppoe = cfg.wan.ipv4.type == "pppoe";
vlan = cfg.wan.ipv4.pppoe.vlan;
vlanDevice = "${cfg.wan.interface}.${toString vlan}";
@@ -20,7 +25,7 @@ let
lib.unique (map (l: l.interface) vlanLans)
);
dhcp = if pppoe then (if v6 then "ipv6" else "no") else (if v6 then "yes" else "ipv4");
dhcp = if pppoe then (if v6native then "ipv6" else "no") else (if v6 then "yes" else "ipv4");
in
{
config = lib.mkIf cfg.enable {
@@ -66,10 +71,15 @@ in
networkConfig = {
DHCP = dhcp;
}
// lib.optionalAttrs v6 {
// lib.optionalAttrs v6native {
IPv6AcceptRA = true;
KeepConfiguration = "yes";
}
// lib.optionalAttrs (pppoe && !v6native) {
# IPv6 (if any) lives inside the PPP session, never on the link.
LinkLocalAddressing = "no";
IPv6AcceptRA = false;
}
// lib.optionalAttrs (pppoe && vlan != null) {
VLAN = [ vlanDevice ];
};
@@ -78,7 +88,7 @@ in
# The router runs its own resolver; never adopt the ISP's DNS for the host.
dhcpV4Config.UseDNS = false;
}
// lib.optionalAttrs v6 {
// lib.optionalAttrs v6native {
# The ISP sends RAs (default route) without DHCPv6 flags, so solicit anyway.
dhcpV6Config = {
WithoutRA = "solicit";
@@ -87,6 +97,23 @@ in
};
};
}
// lib.optionalAttrs v6ppp {
# IPv6 inside the PPP session: pppd (IPv4, IPv6CP link-local) creates the
# device; networkd takes RAs and DHCPv6 (prefix delegation) on it.
"12-wan-ppp" = {
matchConfig.Name = cfg.wan.ipv4.interface;
networkConfig = {
DHCP = "ipv6";
IPv6AcceptRA = true;
KeepConfiguration = "yes";
};
dhcpV6Config = {
WithoutRA = "solicit";
UseDelegatedPrefix = true;
UseDNS = false;
};
};
}
// lib.optionalAttrs (pppoe && vlan != null) {
# pppd configures the session; networkd only has to bring the device up.
"11-wan-pppoe" = {
@@ -118,7 +145,7 @@ in
}
// lib.optionalAttrs lan.ipv6.pd {
dhcpPrefixDelegationConfig = {
UplinkInterface = cfg.wan.interface;
UplinkInterface = v6dev;
SubnetId = 0;
Announce = true;
Assign = true;