idle traffic considerations

idle traffic considerations

[Knuth]

Hey,

we are planning to deploy certain devices with an embedded sim cards in 
different countries across the globe, for maintenance we need to be able 
to connect to the devices with ssh.

Since the sim cards only provide us with a private IPv4 behind NAT 
(because apparently IPv6 is still hard...) we need to reverse the 
connection process to our control system,
at the moment we consider doing this with wireguard (we are aware of the 
"pre" release status), since we had good experiences with it on other 
similar setups.

To calculate some rough estimated costs for the mobile connection 
traffic volume, i'd love to know if there is a way to calculate the 
amount of traffic caused by an idle wireguard connection kept alive 
since we would be charged per MByte transferred.
Or do we simply have to setup a few test subjects and monitor it over a 
longer time, which in itself could be error prone.


Thanks for your time
Knuth

_______________________________________________
WireGuard mailing list
WireGuard@lists.zx2c4.com
https://lists.zx2c4.com/mailman/listinfo/wireguard

Re: idle traffic considerations

[zrm]

On 10/17/19 06:29, Knuth wrote:
> Hey,
> 
> we are planning to deploy certain devices with an embedded sim cards in 
> different countries across the globe, for maintenance we need to be able 
> to connect to the devices with ssh.
> 
> Since the sim cards only provide us with a private IPv4 behind NAT 
> (because apparently IPv6 is still hard...) we need to reverse the 
> connection process to our control system,
> at the moment we consider doing this with wireguard (we are aware of the 
> "pre" release status), since we had good experiences with it on other 
> similar setups.
> 
> To calculate some rough estimated costs for the mobile connection 
> traffic volume, i'd love to know if there is a way to calculate the 
> amount of traffic caused by an idle wireguard connection kept alive 
> since we would be charged per MByte transferred.
> Or do we simply have to setup a few test subjects and monitor it over a 
> longer time, which in itself could be error prone.
> 
> 
> Thanks for your time
> Knuth

Ballpark estimate, round a keepalive packet to about a hundred bytes. 
You're also going to get a re-keys, call those two hundred bytes. If you 
have a keepalive every 30 seconds and a re-key every 120 seconds, that's 
around 18KB per hour per peer in each direction.

This scales inversely with the keepalive interval, and if it's longer 
than 120 seconds then the idle rekeys happen less often too. How short 
you can get away with depends on how long your network provider(s) 
continue to track idle UDP flows. RFC4787 Section 4.3 recommends five 
minutes and requires at least two minutes here, but you may still want 
to test and make sure you don't have a crappy network provider that 
violates the RFC.

It's also best to test the results empirically in any event. We can 
estimate about how big a keepalive packet is but if you've got a bug 
sending them every 60ms instead of every 60s you'll be happy to catch it 
before the bill comes in across your entire fleet.
_______________________________________________
WireGuard mailing list
WireGuard@lists.zx2c4.com
https://lists.zx2c4.com/mailman/listinfo/wireguard

Re: idle traffic considerations

[Lonnie Abelbeck]

> On Nov 29, 2019, at 3:18 PM, zrm <zrm@trustiosity.com> wrote:
> 
> On 10/17/19 06:29, Knuth wrote:
>> Hey,
>> we are planning to deploy certain devices with an embedded sim cards in different countries across the globe, for maintenance we need to be able to connect to the devices with ssh.
>> Since the sim cards only provide us with a private IPv4 behind NAT (because apparently IPv6 is still hard...) we need to reverse the connection process to our control system,
>> at the moment we consider doing this with wireguard (we are aware of the "pre" release status), since we had good experiences with it on other similar setups.
>> To calculate some rough estimated costs for the mobile connection traffic volume, i'd love to know if there is a way to calculate the amount of traffic caused by an idle wireguard connection kept alive since we would be charged per MByte transferred.
>> Or do we simply have to setup a few test subjects and monitor it over a longer time, which in itself could be error prone.
>> Thanks for your time
>> Knuth
> 
> Ballpark estimate, round a keepalive packet to about a hundred bytes. You're also going to get a re-keys, call those two hundred bytes. If you have a keepalive every 30 seconds and a re-key every 120 seconds, that's around 18KB per hour per peer in each direction.

I had a similar use case as Knuth described, zrm's estimate is right on target.

Using a Netgear LB1121 as a 4G/LTE Endpoint, native IPv4-only behind NAT to a static IPv4 public server.

## 4G/LTE Endpoint
PersistentKeepalive = 25

## Static Endpoint
PersistentKeepalive = 0

When idle the WireGuard VPN consumes less than 0.5 MB/day of data.

Lonnie

_______________________________________________
WireGuard mailing list
WireGuard@lists.zx2c4.com
https://lists.zx2c4.com/mailman/listinfo/wireguard

Re: idle traffic considerations

[Roman Mamedov]

On Fri, 29 Nov 2019 16:18:52 -0500
zrm <zrm@trustiosity.com> wrote:

> Ballpark estimate, round a keepalive packet to about a hundred bytes. 
> You're also going to get a re-keys, call those two hundred bytes. If you 
> have a keepalive every 30 seconds and a re-key every 120 seconds, that's 
> around 18KB per hour per peer in each direction.

And read the small-print of mobile carrier plans, at least in our country[1]
they love so much to tally-up the user transferred data every hour, while also
rounding that up to nearest 250 KB, or even 1 MB. So even in the above
scenario they would bill for at least 250 KB/hour.

[1] http://tyumen.megafon.ru/tariffs/all/megafon-online.html

-- 
With respect,
Roman
_______________________________________________
WireGuard mailing list
WireGuard@lists.zx2c4.com
https://lists.zx2c4.com/mailman/listinfo/wireguard