I recently started using the HEC with TLS on my standalone testing instance and now I am seeing some behavior that I cannot make sense of. I assume that it is related to the fact that I configured both, TCP Input and HEC Input to use different certificates. The HEC Input is working fine, but when a UF tries to connect to the TCP Input, I get this error: 05-22-2025 07:39:18.469 +0000 ERROR TcpInputProc [2339416 FwdDataReceiverThread] - Error encountered for connection from src=REDACTED:31261. error:14089086:SSL routines:ssl3_get_client_certificate:certificate verify failed - please check the output of the `openssl verify` command for the certificates involved; note that if certificate verification is enabled (requireClientCert or sslVerifyServerCert set to "true"), the CA certificate and the server certificate should not have the same Common Name.
05-22-2025 07:39:18.555 +0000 ERROR X509Verify [2339416 FwdDataReceiverThread] - Client X509 certificate (CN=REDACTED,CN=A,OU=B,DC=C,DC=D,DC=E) failed validation; error=19, reason="self signed certificate in certificate chain"
05-22-2025 07:39:18.555 +0000 WARN SSLCommon [2339416 FwdDataReceiverThread] - Received fatal SSL3 alert. ssl_state='error', alert_description='unknown CA'.
05-22-2025 07:39:18.555 +0000 ERROR TcpInputProc [2339416 FwdDataReceiverThread] - Error encountered for connection from src=10.253.192.20:32991. error:14089086:SSL routines:ssl3_get_client_certificate:certificate verify failed - please check the output of the `openssl verify` command for the certificates involved; note that if certificate verification is enabled (requireClientCert or sslVerifyServerCert set to "true"), the CA certificate and the server certificate should not have the same Common Name. On the UF, I can see the following error message: 05-22-2025 07:39:17.953 +0000 WARN SSLCommon [1074 TcpOutEloop] - Received fatal SSL3 alert. ssl_state='SSLv3 read server session ticket A', alert_description='unknown CA'.
05-22-2025 07:39:17.953 +0000 ERROR TcpOutputFd [1074 TcpOutEloop] - Connection to host=REDACTED:9997 failed Below are my config files. I appreciate any pointers as to what I did wrong. Note: All files which are storing certificates are the "usual" order: For clientCert and serverCert First certificate, then private key For sslRootCAPath First issuing, then Root CA Standalone/Indexer: Server.conf [sslConfig]
sslRootCAPath = /opt/splunk/etc/auth/mycerts/cert.pem Inputs.conf [splunktcp-ssl:9997]
disabled=0
[SSL]
serverCert = /opt/splunk/etc/auth/mycerts/cert0.pem
sslPassword = REDACTED
requireClientCert = true
sslVersions = tls1.2
[http]
disabled = 0
enableSSL = 1
serverCert = /opt/splunk/etc/auth/mycerts/cert1.pem
sslPassword = REDACTED
[http://whatthehec]
disabled = 0
token = REDACTED UF: server.conf [sslConfig]
serverCert = /mnt/certs/cert0.pem
sslPassword = REDACTED
sslRootCAPath = /mnt/certs/cert.pem
sslVersions = tls1.2 outputs.conf: [tcpout]
defaultGroup = def
forwardedindex.2.whitelist = (_audit|_introspection|_internal)
[tcpout:def]
useACK = true
server = server:9997
autoLBFrequency = 180
forceTimebasedAutoLB = false
autoLBVolume = 5000000
maxQueueSize =100MB
connectionTTL = 300
heartbeatFrequency = 350
writeTimeout = 300
sslVersions = tls1.2
clientCert = /mnt/certs/cert0.pem
sslRootCAPath = /mnt/certs/cert.pem
sslPassword = REDACTED
sslVerifyServerCert = true
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