Jichao Wang created DIRKRB-761:
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Summary: The ticket validity period obtained by the Kerberos
client may be larger than the maximum set on the KDC
Key: DIRKRB-761
URL: https://issues.apache.org/jira/browse/DIRKRB-761
Project: Directory Kerberos
Issue Type: Bug
Affects Versions: 2.0.2, 2.0.1, 2.0.0
Reporter: Jichao Wang
Fix For: 2.0.3
The ticket lifetime obtained by the Kerberos client may be greater than the
maximum lifetime configured on the KDC (maximum_ticket_lifetime)
The contents of kdc.conf are as follows:
{code:java}
[kdcdefaults]
kdc_host = krb-wjc-kerberos-0
kdc_udp_port = 88
kdc_tcp_port = 88
kdc_realm = HADOOP.COM
encryption_types = aes256-cts-hmac-sha1-96 aes128-cts-hmac-sha1-96
preauth_required = false
maximum_renewable_lifetime = 0
maximum_ticket_lifetime = 86400
minimum_ticket_lifetime = 0 {code}
Based on the above configuration, the maximum ticket lifetime obtained by the
Kerberos client should be 1 day. However, when I use the following krb5.conf
and methods to obtain the ticket, the lifetime of the ticket is 3 days, which
is larger than the maximum set on KDC of 1 day.
The contents of krb5.conf are as follows:
{code:java}
[libdefaults]
dns_lookup_realm = false
dns_lookup_kdc = false
ticket_lifetime = 72h
renew_lifetime = 0
forwardable = false
renewable = false
rdns = false
default_realm = HADOOP.COM
default_ccache_name = /tmp/krb5cc_%{uid}
udp_preference_limit = 1
[realms]
HADOOP.COM = {
kdc = krb-wjc-kerberos-0
} {code}
First install the Kerberos client on the Centos7 operating system by running
the following command:
yum install -y krb5-devel krb5-workstation
Then use kinit to get the ticket from KDC and use the klist command to view the
ticket:
{code:java}
[root@localhost wjc]# kinit had...@hadoop.com
Password for had...@hadoop.com:
[root@localhost wjc]# klist
Ticket cache: FILE:/tmp/krb5cc_0
Default principal: had...@hadoop.com
Valid starting Expires Service principal
12/03/2022 16:44:10 12/06/2022 16:44:10 krbtgt/hadoop....@hadoop.com
renew until 12/03/2022 16:44:10 {code}
We can see that the lifetime of the Kerberos ticket is 3 days, which is larger
than the 1 day set in kdc.conf. This may cause security risks.
So I think this is a bug.
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