I am no able to connect to mongodb via mongo shell.


sudo mongo --tls --tlsCertificateKeyFile server.pem --tlsCAFile CA_INTERMEDIATE --host "mongodb://xxx:xxx@some-url:27020/data_base?ssl=true"


MongoDB shell version v4.4.3
connecting to: mongodb://some-url:27020/data_base?compressors=disabled&gssapiServiceName=mongodb&ssl=true
{"t":{"$date":"2021-01-08T14:55:17.158Z"},"s":"E",  "c":"NETWORK",  "id":23256,   "ctx":"js","msg":"SSL peer certificate validation failed","attr":{"error":"SSL peer certificate validation failed: unable to verify the first certificate"}}
Error: couldn't connect to server some-url:27020, connection attempt failed: SSLHandshakeFailed: SSL peer certificate validation failed: unable to verify the first certificate :
exception: connect failed
exiting with code 1

However, this works when I am using the same keys, certificate and parameters with mongoDB Compas.

enter image description here

can someone please tell me what I am doing wrong?

1 Answer 1


I suspect Compass is falling back on the system trust store while the command line tool is not.

Capture the certificate presented by the server:

openssl s_client -connect some-url:27020 </dev/null > retrieved_cert.pem

And then validate using the CA certificate:

openssl verify -CAfile CA_INTERMEDIATE retrieved_cert.pem

If validation succeeds, you should see

retrieved_cert.pem: OK

If that doesn't work, take a look at the subject and issuer of each certificate, and ensure that the file passed to --tlsCAFile contains the self-signed root certificate at the head of the chain.

  • I've tried the same command with same keys on the instance where Compass is running and it worked. so you are right, it is using the system trust store. is there anyway to find out which certificate from system store being used in this case?
    – roAl
    Jan 8, 2021 at 18:57
  • Run openssl x509 -in CA_INTERMEDIATE -noout -subject -issuer to see which CA issued that certificate.
    – Joe
    Jan 11, 2021 at 10:00
  • I've noticed something strange. when I do openssl verify on windows 10 instance from git bash I get "ok" response. but when I do it on ubuntu 20 instance then I get the (unable to get local issuer certificate) error
    – roAl
    Jan 11, 2021 at 10:21

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