[atlas] Disparity between reported results from probes and actual situation?

Hi there,


There are some sites that are being blocked by ISPs here in India. The 
two cases I checked are,

1. mega.nz

2. t.me

In some cases, It's the Consumer ISP that's blocking access to these 
domains and in other cases it's the upstream providers like 
Tata(AS17908) that are blocking access to these sites.

To figure out how many probes were effected, I ran 2 TLS tests. The 
results of those tests are here,

1. https://atlas.ripe.net/measurements/32358061/

2. https://atlas.ripe.net/measurements/32358052/


As you'll see that almost every probe received correct TLS Certificate 
with mega.nz and excluding 4-5 probes, All the other probes received 
correct certificates for t.me. These measurements include 2 probes that 
I run in AS9829 and AS45609. Somehow, Both of my probes reported that 
they received the correct/valid certificate in both of these measurement 
when it doesn't appear to be true.

I am presented with connection closed error when accessing these sites 
over HTTP and a connection reset error when accessing these sites over 
HTTPS over both WANs used by the two probes.


Have I misunderstood TLS tests? I am not sure what is happening here and 
I really appreciate any insight I can get on these results. I have also 
included the relevant section from the logs of 1 of my probes.


atlas_run: looking for 'evsslgetcert -4 -p 443 -h mega.nz -A "32358061" 
66.203.127.18'
eooqd: found cmd 'evsslgetcert' for 'evsslgetcert -4 -p 443 -h mega.nz 
-A "32358061" 66.203.127.18'
eooqd: atlas_run: argv[0] = 'evsslgetcert'
eooqd: atlas_run: argv[1] = '-4'
eooqd: atlas_run: argv[2] = '-p'
eooqd: atlas_run: argv[3] = '443'
eooqd: atlas_run: argv[4] = '-h'
eooqd: atlas_run: argv[5] = 'mega.nz'
eooqd: atlas_run: argv[6] = '-A'
eooqd: atlas_run: argv[7] = '32358061'
eooqd: atlas_run: argv[8] = '66.203.127.18'
eooqd: atlas_run: argv[9] = '-O'
eooqd: atlas_run: argv[10] = '/var/atlas-probe/data/new/ooq.2'
eooqd: init returned 0x738200 for 'evsslgetcert -4 -p 443 -h mega.nz -A 
"32358061" 66.203.127.18'
eooqd: check_resolv_conf2: no change (time 1632496526)
msgbuf_read: buf_read failed
ooqd: command is done for cmdstate 0x738200
sslgetcert_delete: state 0x738200, index 0, busy 0
total size in dir: 5982
httppost: before getaddrinfo
httppost: before connect
httppost: sending request
posting file '/var/atlas-probe/data/out/ooq/2'
httppost: getting result
httppost: getting reply headers
httppost: got line 'Server: nginx'
httppost: got line 'Date: Fri, 24 Sep 2021 15:56:32 GMT'
httppost: got line 'Content-Type: text/plain'
httppost: got line 'Transfer-Encoding: chunked'
httppost: got line 'Connection: close'
httppost: writing output
httppost: chunked 1, content_length -1
httppost: got chunk line '3'
httppost: chunk data 'OK



Regards
Ishan Jain