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Ukraine’s Wartime Internet from the Inside

Doug Madory
Doug MadoryDirector of Internet Analysis

Internet Analysis


It has now been over a year since Russian forces invaded its neighbor to the west leading to the largest conflict in Europe since World War II. Kentik’s Doug Madory reviews what has happened with internal connectivity within Ukraine over the course of the war in this analysis done for a collaboration with the Wall Street Journal.

This February marked a grim milestone in the ongoing war in Ukraine. It has now been over a year since Russian forces invaded its neighbor to the west leading to the largest conflict in Europe since World War II.

In the past year, we have used Kentik’s unique datasets to show some of the conflict’s impacts on Ukraine’s external internet connectivity, ranging from DDoS attacks and large outages, to the rerouting of internet service in the southern region of Kherson.

This blog post contains analysis done for a collaboration with the Wall Street Journal (pictured below) using a novel data source that allows us to explore connectivity inside Ukraine: the Ark dataset from the Center for Applied Internet Data Analysis (CAIDA).

Wall Street Journal Ukraine diagram with Kentik data
Kentik analysis on Ukraine in the Wall Street Journal, March 6, 2023

Domestic measurements using the Ark dataset

Based at the University of California San Diego, the Center for Applied Internet Data Analysis (CAIDA) is a leader in the academic field of internet measurement. Among their numerous measurement projects is the Archipelago Measurement Infrastructure, or Ark, for short. Ark consists of servers located around the world continuously performing traceroutes to randomly selected IP addresses.

One of those Ark servers is located in Kyiv. For the past year, it has been dutifully performing measurements to IP addresses around the world, including destinations within Ukraine and Russia. CAIDA graciously provided the data generated from this server to Kentik for the following analysis.

The data gives us a unique view into the internal connectivity within Ukraine over the course of the war — at least from the perspective of this one important internet connection in Kyiv.

Arguably the most dramatic development that appears in the data was the rerouting of internet service to Kherson through Russia. To analyze this development, we extracted the traceroutes performed by the Ark server in Kyiv to IP address space originated by the ASes of Kherson.

The data from these traceroutes is plotted below by the overall latency (y-axis), time of measurement (x-axis), and AS origin of the last responding hop (color).

Traceroutes in Kiev to Kherson

There is a clear point when the latencies increase due to the Russian rerouting at the beginning of June 2022. As one would expect, this aligns with the timing observable in BGP. The above graphic also illustrates the result of the Ukrainian liberation effort in Kherson. Ukrainians have recaptured half of the region, and we see a portion of the traceroutes reverting to a lower latency as those networks restore their Ukrainian transit connections. A few providers in the region of Kherson are still on Russian transit, presumably in the territory that is still under Russian control.

If we isolate the measurements to one particular ASN in Kherson, AS21151 (Ukrcom), the traceroutes tell a clear story of the network’s transition from Ukrainian to Russian transit and back again.

Isolated view of traceroutes in Kherson

If we convert the individual traceroutes used in the above graphic into a readable version, we can see how the internet path between Kyiv and Kherson changed hop-by-hop.

Before the invasion, packets could get from Kyiv to Kherson in as little as 11ms:

Traceroute from to at 2022-01-20 00:34:58 (COMPLETED):

  1.    PJSC Datagroup      3326    0.999   
  2.      UBNIX-GLOBAL-IX     199524               0.724   
  3.  3255                                        14.859  
  4.   Ukrcom Ltd          21151                                       12.551  
  5.  Ukrcom Ltd          21151  11.824  
  6.   Ukrcom Ltd          21151   11.883  

During the Russian occupation, traceroutes needed to leave the country to reach Kherson. In the example below, this traceroute travels from Kyiv to Vienna win to Frankfurt ffm to Moscow 12389 to Simferopol, Crimea smfl and finally to Kherson 21151.

Traceroute from to at 2022-06-13 18:52:08 (GAPLIMIT):

  1.   PJSC Datagroup                  3326                   0.504    
  2.   PJSC Datagroup                  3326           0.62     
  3.   TELIANET                        1299                      0.825    
  4.  TELIANET                        1299                      32.405   
  5.   TELIANET                        1299                      31.878   
  6.   TELIANET                        1299  64.392   
  7.   PJSC Rostelecom                 12389                                                      46.853   
  8.   Miranda-Media Ltd               201776                                                     76.742   
  9.   Osipenko Alexander Nikolaevich  201776         94.087   
  10.  Ukrcom Ltd                      21151                  103.082  
  11.  Ukrcom Ltd                      21151                                                      105.668  
  12.    Ukrcom Ltd                      21151                    95.683  

As a consequence of the greatly increased geographic distance traveled, the overall latencies from Kyiv to Kherson jumped up to over 70ms - greater than a round-trip time across the Atlantic Ocean.

Following the liberation of Kherson, traceroutes revert to a shorter, more direct path:

Traceroute from to at 2022-12-06 22:50:52 (GAPLIMIT):

  1.    PJSC Datagroup        3326  18.287  
  2.     UA-EUROLINE-20210701  None               0.41    
  3.  Ukrcom Ltd            21151         10.254  
  4.   Ukrcom Ltd            21151                                    10.253  
  5.   Ukrcom Ltd            21151      9.983  

Not every Kherson AS switched back to Ukrainian transit. Russia still occupies half of the region, and a few ASes operate in that half. RubinTelecom (AS49465) is one of them and remains on Russian transit. It also suffered extended outages.

RubinTelecom Outages

Connectivity to Donbas

Measurements to Russian-held Donetsk and Luhansk also exhibited clear changes in latency and path. We can’t be sure whether these changes were due to a technical failure along a more direct path or an administrative disabling of the link. On February 17, 2022 — one full week before the invasion — we saw latencies to Luhansk double from 35ms to 70ms.

Measurements from Kiev to Russian-held Luhansk

Looking at the individual traceroutes shows a clear change in path. Initially, the measurements heading to Russian-held Luhansk headed directly to the Moscow Internet Exchange (MSK-IX) by way of Kharkiv on Ukraine’s northeast border with Russia, as illustrated in the traceroute below:

Traceroute from to at 2022-02-14 19:39:45 (COMPLETED):

  1.    PJSC Datagroup        3326           0.244
  2.    PJSC Datagroup        3326  31.632 
  3.      PJSC Datagroup        3326   35.792 
  4.   MSK-IX                None                                              42.23
  5.  Telematika LLC        43201                                             33.902 
  6.     Luganet               39728                           34.875 
  7.   Luganet               39728                                             35.3 

After the change, traceroutes had to head west to DECIX in Frankfurt before getting carried to Moscow in Rostelecom and then on to Luhansk in Eastern Ukraine.

Traceroute from to at 2022-02-17 23:44:13 (COMPLETED):

  1.    PJSC Datagroup       3326          0.583
  2.    PJSC Datagroup       3326  30.813
  3.     DE-CIX Management    6695           32.264
  4.  PJSC Rostelecom      12389                                            94.839
  5.    PJSC Rostelecom      12389                                            67.917
  6.  Telematika LLC       43201                                            94.294
  7.     Luganet              39728                         67.113
  8.   Luganet              39728                                            69.986

Datagroup’s connection to Russia via Kharkiv appears to have been disabled ahead of the invasion, perhaps as a measure to thwart cyberattacks from Russia.

In mid-March, traceroutes from Kyiv to Russian-held Donetsk exhibited a similar leap in latency, from as low as 34ms to over 80ms:

Traceroutes from Kiev to Russian-held Donetsk

Connectivity to Russia

Below is an illustration of the traceroutes from the Ark server in Kyiv through Russian state telecom, Rostelecom (AS12389), to any global destination. These are traceroutes that received responses from the target addresses (i.e., status = COMPLETED) and, again, are plotted by the overall latency (y-axis), time of measurement (x-axis), and AS origin of the target IP (color).

Traceroutes from Kiev through Rostelecom

The chart above reveals that traceroutes destined for address space originated by Rostelecom (AS12389, AS42610, AS25490, etc.) and many other Russian networks became unreachable. But the traceroutes didn’t begin and then stop at a certain point. Instead, beginning around 09:00 UTC on February 28, 2022, Datagroup appeared to simply no longer carry any routes from many Russian ASNs in its routing table.

The Ark server did, however, continue to successfully run traceroutes through Rostelecom on to other countries: notably Kazakhstan and Iran. In the graphic above, traceroutes to Kazakh Telecom (AS9198) appear in green, while traceroutes to Iran’s Information Technology Company (AS58224) appear in purple. This is to be expected as both countries normally utilize Russian transit.

The lower band of measurements in yellow and dark gray represent successful traceroutes into Russian-held Donbas and Crimea — perhaps demonstrating a reluctance to block traffic to any parts of Ukraine, even if occupied by Russian forces.


The analysis above only scratches the surface of what is contained in the measurement data that was produced by CAIDA’s Ark server in Kyiv. Traceroutes performed from inside Ukraine can reveal changes in latency and path for domestic traffic that isn’t possible to observe from outside of the country.

In the case of Kherson, the internal view provided by Ark revealed the performance impact of forcibly re-routing domestic traffic through an external country. Of course, the issue of increased latency pales in comparison to the security concerns that arise from having one’s communications re-routed through an invading country.

Recall Skynet (formerly Kherson Telecom) was the first ISP in Kherson to begin using Russian transit in May of 2022. It was an action that the CEO defended on social media. After the Ukrainian counteroffensive in the fall of 2022 recaptured much of the region of Kherson and ISPs there started using Ukrainian transit again, Skynet went dark. Since then, it hasn’t appeared in the global routing table.

The war in Ukraine has devastated the country, and its telecommunications infrastructure, while still operational, has paid a heavy price. For most of Ukraine, the Russian-held Donbas got further away, both in terms of internet distance and national cohesion, while much of the Russian internet became unreachable.

Ukrainian telecommunications technicians are continuing to face unforgiving challenges while working to keep Ukriane connected to the outside world and, of course, from the inside.

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