On Tuesday, May 24, 2016 10:07:57 AM Ken Bass wrote:
On 05/23/2016 11:21 AM, Ken Bass wrote:
> I enabled krb5 in my audisp-remote and audispd-remote reports "GSS-API
> error sending token length" and fails to log remotely.
>
> If I reboot the destination auditd server AFTER the clients are
> running it appears to work. But if I reboot any clients machine,
> logging from that rebooted machine fails.
> I created my service principals using freeipa - all systems are clean
> installs of Centos 7.2.
>
> For now, I disabled krb5, but that is not a good solution.
After disabling krb5 and rebooting the client servers several times I am
seeing similar problems. I am seeing a dozen or so log file entries of
Too many connections from 10.10.10.10:39107 - rejected
I only have 2 clients and all I am doing is rebooting them. I tried
increasing the tcp_listen_queue to 20 (from the default of 5) which made
no difference.
I seem to have traced it to needing to specify the tcp_client_ports to
60 rather than using whatever the default was. What would have been
blocking this?
I think 60 is the default in the audit config files. IPtables/firewalld needs to
be opened and selinux is expecting port 60.
And why only when the clients are rebooted second does it
fail?
After changing this the Kerberos works, so I think the 'error sending
token length' is basically the same message but in a different code path
to indicate the connection is rejected / cannot write to the TCP socket.
Was the commented out ##tcp_client_ports parameter supposed to be
changed by the end user? Was the defaults supposed to work?
There is some discussion of this in the man pages. Ports < 1024 are
privileged. If its higher they you can have someone dump spoofed log events in
the aggregating server. So, setting the port low gives a small amount of trust
that it might be real events from a real system. You should also use
tcp_wrappers to make sure specific systems are sending events. Kerberos though
is supposed to help ensure that you have even more trust.
-Steve
On a related note, using krb5 causes a problem with selinux. Unless
I
disable it (or figure out a rule) auditd fails to start because it is
denied permission to create /var/tmp/auditd_0 kerberos replay cache file.
Is there a rule or procedure to properly fix that?
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