问题描述：
使用Kafka客户端通过21007端口访问开启Kerberos的集群报以下错误：
javax.security.sasl.SaslException: An error: (java.security.PrivilegedActionException: javax.security.sasl.SaslException: GSS initiate failed [Caused by GSSException: No valid credentials provided (Mechanism level: Server not found in Kerberos database (7) - UNKNOWN_SERVER)]) occurred when evaluating SASL token received from the Kafka Broker、This may be caused by Java's being unable to resolve the Kafka Broker's hostname correctly、You may want to try to adding '-Dsun.net.spi.nameservice.provider.1=dns,sun' to your client's JVMFLAGS environment、Users must configure FQDN of kafka brokers when authenticating using SASL and `socketChannel.socket().getInetAddress().getHostName()` must match the hostname in `principal/hostname@realm` Kafka Client will go to AUTH_FAILED state.
at org.apache.kafka.common.security.authenticator.SaslClientAuthenticator.createSaslToken(SaslClientAuthenticator.java:293)
at org.apache.kafka.common.security.authenticator.SaslClientAuthenticator.sendSaslToken(SaslClientAuthenticator.java:210)
at org.apache.kafka.common.security.authenticator.SaslClientAuthenticator.authenticate(SaslClientAuthenticator.java:178)
at org.apache.kafka.common.network.KafkaChannel.prepare(KafkaChannel.java:64)
at org.apache.kafka.common.network.Selector.pollSelectionKeys(Selector.java:338)
at org.apache.kafka.common.network.Selector.poll(Selector.java:291)
at org.apache.kafka.clients.NetworkClient.poll(NetworkClient.java:260)
at org.apache.kafka.clients.producer.internals.Sender.run(Sender.java:236)
at org.apache.kafka.clients.producer.internals.Sender.run(Sender.java:135)
at java.lang.Thread.run(Thread.java:745)
Caused by: javax.security.sasl.SaslException: GSS initiate failed
at com.sun.security.sasl.gsskerb.GssKrb5Client.evaluateChallenge(GssKrb5Client.java:211)
at org.apache.kafka.common.security.authenticator.SaslClientAuthenticator$2.run(SaslClientAuthenticator.java:275)
at org.apache.kafka.common.security.authenticator.SaslClientAuthenticator$2.run(SaslClientAuthenticator.java:273)
at java.security.AccessController.doPrivileged(Native Method)
at javax.security.auth.Subject.doAs(Subject.java:422)
at org.apache.kafka.common.security.authenticator.SaslClientAuthenticator.createSaslToken(SaslClientAuthenticator.java:273)
..、9 common frames omitted
Caused by: org.ietf.jgss.GSSException: No valid credentials provided (Mechanism level: Server not found in Kerberos database (7) - UNKNOWN_SERVER)
at sun.security.jgss.krb5.Krb5Context.initSecContext(Krb5Context.java:770)
at sun.security.jgss.GSSContextImpl.initSecContext(GSSContextImpl.java:248)
at sun.security.jgss.GSSContextImpl.initSecContext(GSSContextImpl.java:179)
at com.sun.security.sasl.gsskerb.GssKrb5Client.evaluateChallenge(GssKrb5Client.java:192)
..、14 common frames omitted
Caused by: sun.security.krb5.KrbException: Server not found in Kerberos database (7) - UNKNOWN_SERVER
at sun.security.krb5.KrbTgsRep.
(KrbTgsRep.java:73) at sun.security.krb5.KrbTgsReq.getReply(KrbTgsReq.java:259)
at sun.security.krb5.KrbTgsReq.sendAndGetCreds(KrbTgsReq.java:270)
at sun.security.krb5.internal.CredentialsUtil.serviceCreds(CredentialsUtil.java:302)
at sun.security.krb5.internal.CredentialsUtil.acquireServiceCreds(CredentialsUtil.java:120)
at sun.security.krb5.Credentials.acquireServiceCreds(Credentials.java:458)
at sun.security.jgss.krb5.Krb5Context.initSecContext(Krb5Context.java:693)
..、17 common frames omitted
Caused by: sun.security.krb5.Asn1Exception: Identifier doesn't match expected value (906)
at sun.security.krb5.internal.KDCRep.init(KDCRep.java:140)
at sun.security.krb5.internal.TGSRep.init(TGSRep.java:65)
at sun.security.krb5.internal.TGSRep.
(TGSRep.java:60) at sun.security.krb5.KrbTgsRep.
(KrbTgsRep.java:55) ..、23 common frames omitted
刚开始遇到报访问timeout或者程序运行卡着看不到或者看到很少的报错信息，后来在项目里添加了日志相关依赖包，才看到比较完整的错误信息。
参考日志依赖：
ch.qos.logback logback-core
1.2.3
ch.qos.logback lagback-classic
1.2.3
org.slf4j slf4j-api
1.7.26
解决方法：
通过报错信息确认可能是服务名称不对，查看KDCServer日志发现：
账号名@xxxx.com for kafka/hadoop.hadoop.com@xxxx.com, Server not found in Kerveros database
对比访问正常的日志使用的服务名是：
kafka/hadoop.xxxx.com@xxxx.com
后在创建Kafka生产者时添加配置项：
kerberos.domain.name = hadoop.xxxx.com
问题解决