Mapping IP Address to Physical Location

Hello & welcome to my talk. @jewelia

Julia Grace @jewelia ! Head of Engineering at Tindie !
! ! !

Location on the Internet @jewelia

IP to location mapping @jewelia

Tindie isn’t just in US @jewelia

Buyers in 60 Countries Sellers in 40 Countries @jewelia

We had a problem. ! ! Hot Mess

That seems a little 90s

Story of how we did it. @jewelia

Step 0: Avoid the problem @jewelia

We had to ﬁx this. @jewelia

Only show shipping rates for the user’s country. @jewelia

How? @jewelia

We had some crazy ideas. @jewelia

No HTML5 Geolocation. @jewelia

IPinfoDB ! “Over 99.5% on a country level and around
60% on a city level for the US within a 25 mile radius.” ! @jewelia

Client side or server side? @jewelia

Server side! @jewelia

Middleware @jewelia

Dancing with the devil ! Set the country in the
session based of X_FORWARDED_FOR ! If there is no country in session, then query IPinfoDB once. Put very strict timeouts and no retries on this. ! If the query fails then don’t show country speciﬁc info. ! @jewelia

Pros ! We have country info! ! Could cache the
IP/Country info in Redis for fast future lookups. ! How often should we update? How often does IP/Country data change? @jewelia

Cons ! We are explicitly introducing latency. ! User pays
a latency penalty on ﬁrst visit; this could leave a bad ﬁrst impression. ! @jewelia

When you start using the word penalty to talk about
a feature, something is very wrong. @jewelia

We deployed it! @jewelia

And it didn’t work. @jewelia

10.x.x.x @jewelia

This is what happens when dev and prod aren’t the
same. @jewelia

Crawlers don’t have sessions. @jewelia

Ran this in prod for a few weeks. @jewelia

Client side! @jewelia

Load in <body> so it won’t block the other content
on page from loading. @jewelia

Pros ! Client side is great for IP based rate-limiting
and throttling! ! (If all of your users are coming from diﬀerent IPs, which most are, versus your server which likely has 1 IP) @jewelia

Cons ! IPinfoDB has no https based endpoint. ! !
@jewelia

This is what happens when dev and prod aren’t the
same. @jewelia

Server side! @jewelia

In nginx we trust. @jewelia

HttpGeoipModule @jewelia

Pros ! Uses MaxMind GeoIP database. ! Unix package (available
via apt-get or aptitude). ! Updated nightly! ! $geoip_country_code — two-letter country code, for example, "RU", "US". ! ! Nginx caches all supplied databases in memory. The country database is small, roughly 1.4M @jewelia

Cons ! Unix experience and server access needed. @jewelia

@jewelia

Thanks! @jewelia

Mapping IP Address to Physical Location

Mapping IP Address to Physical Location

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