IPoE, but static IPv4

Continuing from previous post, at the end I mentioned about using Vultr to avoid paying extra for static IPv4 address through my ISP.

Well, there has been a different problem with IPv4 connection crapping out every now and then so I ended up getting that ISP static IP option hoping it will lessen the problem. No comment on that yet because it’s only been less than 12 hours since I got it set up.

So, the setup itself, because I’m not using one of the supported routers, I had to figure it out myself.

The ISP provides a few needed information for the setup:

  • Static IP Tunnel Endpoint: an IPv6 address to connect for IPv4 connectivity
  • Interface ID: IPv6 address suffix (last 4 group)
    • FreeBSD doesn’t support it (it’s ip-token in Linux) but it really is just for address suffix. Mine’s ::feed so my expected address is 2409:11:1c0:2300::feed. I have it set as external IP address
  • Static IPv4 Address: this is to be set at tunnel interface as source address.
    • There’s no IPv4 target address provided which is required for FreeBSD’s gif interface but apparently any address works. I put in 10.0.0.0
    • This blog says to use source as target as well but apparently it results in packet being forwarded back and forth indicated by 14ms ping to the source IP
  • “Update Server Details”: I have no clue what this actually does
    • It’s a set of URL, username, and password where you’re supposed to make a request to to update… something. The form is simple, just $URL?username=$USERNAME&password=$PASSWORD. The URL uses internal domain so the DNS server from IPv6 autoconfiguration is required to resolve it
    • I just hit it with curl and the move on
    • I suspect it’s to tell the tunnel provider the expected source IPv6 address?

Geared with information above, there are a few changes needed since last post for setup on FreeBSD:

  • IP address on internet port should be suffixed with provided interface ID
  • Tunnel source and target address need to be adjusted
  • Tunnel interface need IPv4 address
  • Default routing for IPv4 is no longer on interface level (-iface gif) but instead the random IPv4 address used as tunnel target address (10.0.0.0 in my example above)
  • NAT is not automatically available anymore so PF is required
  • Also on NAT, MSS will need to be fixed as well
    • I still don’t really understand how this works

Most of the changes should be obvious. And here’s the config for PF:

# This is pf.conf for FreeBSD and won't work on OpenBSD

# variable to not hardcode interface names and stuff
ext_if = gif0
net_local = "192.168.0.0/24"

# I still don't know if this is needed. Or even what the correct value is.
scrub on $ext_if max-mss 1420

# basic nat
nat on $ext_if from $net_local -> ($ext_if)

Leave a Reply

Your email address will not be published.