[tor-relays] Why I do have so often an "8" in my bridge stats?

[David Fifield]

On Tue, Sep 24, 2024 at 04:03:55PM +0200, Toralf Förster via tor-relays wrote:
> Never cared about this before, but isn't the "8" too often here? :
> 
> $ cat ~/tmp/tor_bridge_stats
> i10 bridge-ips
> ru=264,br=16,de=16,us=16,au=8,cl=8,co=8,cz=8,dz=8,eg=8,es=8,fr=8,gb=8,gr=8,hk=8,id=8,in=8,ir=8,it=8,kr=8,lt=8,lv=8,nl=8,ph=8,sa=8,sg=8,tw=8,ua=8,ve=8
> i11 bridge-ips ru=152,ir=16,cn=8,cz=8,de=8,gb=8,nl=8,pl=8,tr=8
> i12 bridge-ips ru=224,by=8,cn=8,de=8,fr=8,in=8,ir=8,jp=8,nl=8,pl=8,ro=8,us=8
> i13 bridge-ips de=8
> i14 bridge-ips de=8,fr=8,ru=8
> i15 bridge-ips de=8,ru=8
> i20 bridge-ips de=8
> i21 bridge-ips de=8
> i22 bridge-ips ru=96,at=8,de=8,nl=8,pl=8,us=8
> i23 bridge-ips
> ru=904,ir=48,eg=32,de=24,us=24,fr=16,ae=8,at=8,be=8,br=8,by=8,ca=8,co=8,cz=8,dz=8,fi=8,gb=8,gr=8,hk=8,hu=8,im=8,in=8,it=8,jp=8,kz=8,lv=8,ma=8,md=8,mm=8,na=8,ni=8,nl=8,pk=8,pl=8,sa=8,se=8,tm=8,tr=8,tz=8,uz=8,ve=8,ye=8,za=8
> i24 bridge-ips de=8
> i25 bridge-ips
> ru=112,ch=8,cn=8,de=8,gh=8,in=8,ir=8,ke=8,mm=8,mu=8,nl=8,tr=8,us=8
> i26 bridge-ips de=8
> luchs bridge-ips de=8

The numbers are rounded to reduce precision.

https://spec.torproject.org/dir-spec/extra-info-document-format.html

>     "bridge-ips" CC=NUM,CC=NUM,... NL
>        [At most once.]
>
> List of mappings from two-letter country codes to the number of unique
> IP addresses that have connected from that country to the bridge and
> which are no known relays, rounded up to the nearest multiple of 8.

https://metrics.torproject.org/reproducible-metrics.html#bridge-users

> From each number of unique IP addresses, subtract 4 to undo the
> binning operation that has been applied by the bridge.