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Dual-stack but IPv4 is CGNAT: what's even the point?

VPS Hosting by kat_fold 38 replies 4.9K views
kat_fold

Moderator OP

Moderator

#1

Hey folks

I've been running a dual-stack VPS on Contabo for six months now and just realized my "public" IPv4 is CGNAT'd. Port forwarding is impossible. My IPv6 works fine, but half the services I need don't listen on v6 yet. What's even the point of advertising dual-stack if one stack is effectively useless behind carrier-grade NAT? Feels like false advertising. I can get the same result from a €3 NAT box at OVHcloud.

Am I missing something here, or is this just the new normal we have to accept?

~be kind or be gone~
marcus_qc

Member

#2

Hey folks

Gonna be real with you, CGNAT ipv4 is basically a participation trophy at this point

Super stoked about IPv6 tho, that's where the fire's at

For port forwarding, I just run a $2 wireguard tunnel to a v4 box at Hetzner (https://www.hetzner.com/cloud) and call it a day. Not elegant but it works.

42U and still growing
FyreJun

Member

#3

Let us consider that dual-stack traditionally implies functional parity between protocols. I apologize for any inconvenience my observation may cause.

It is my understanding that some users have employed reverse tunnels via third-party infrastructure. I do not wish to overstep, but let us perhaps demand clearer labeling from our hosts.

srelet

Member

#4

Transparency: we ran CGNAT IPv4 at my last gig for 18 months before anyone noticed. Error budget was blown on discovery, not mitigation.

Blameless postmortem revealed our own monitoring only hit v6 endpoints. The v4 path was dark.

If you need inbound v4, treat CGNAT as "v4 outbound only" and architect accordingly. Separate concern. Run a tiny relay somewhere else or accept the constraint. No provider will give you clean v4 at these price points anymore—transparency about that would help, but market pressures.

LA

Member

#5

Contabo never called it "outbound-only v4" though, did they?

svendeal

Member

Deal Sniper

#6

Same issue with OVHcloud, gave up on inbound v4 entirely

world record: 4min Arch install
sam3

Member

#7
LAZY23 said:
Contabo never called it "outbound-only v4" though, did they?

No they didn't, and that's the rub. In payments we have to label everything—interchange++, scheme fees, the lot. Hosting gets away with "dual-stack" meaning "one and a half stacks" because there's no regulator looking.

I moved off Contabo to Hetzner Cloud in Falkenstein last year. Clean v4, clean v6, €4.51/month for the smallest CX11. Not affiliated, just a customer who got tired of explaining to clients why their webhook callbacks failed.

https://www.hetzner.com/cloud

marcus_qc

Member

#8
srelet said:
No provider will give you clean v4 at these price points anymore

OVHcloud will, actually. Their Starter VPS in Beauharnois is €3.50, real IPv4, no NAT. I have six of them for clients who need SMTP egress. The catch is it's IPv4-only unless you pay more for v6, which is... backwards, but there you go.

42U and still growing
LA

Member

#9
marcus_qc said:
OVHcloud will, actually. Their Starter VPS in Beauharnois is €3.50, real IPv4

Beauharnois latency from Sofia is 120ms+. Fine for mail, useless for anything interactive. CGNAT or not, Contabo's German DCs are 30ms for me. Trade-offs everywhere.

lucgone

Member

Le Baguette

#10
kat_fold said:
Feels like false advertising

C'est exactement ça. In Lyon we have SFR with CGNAT on residential fibre, everyone knows, nobody pretends it's "dual-stack." Contabo should write "IPv6 + IPv4 sortant" and be done.

I run a small Proxmox at Online.net (Scaleway now) for personal stuff. Real IPv4, real IPv6, no surprises. More expensive, mais au moins c'est honnête.

Vive la résistance... électrique

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