In my case krb5kdc ist running out of leck mich, cause the host system hasn't realy enough system resources.

The correct thing to do is adjust net.ipv4.tcp_max_syn_backlog to a high enough value that it no longer fires this warning.

You will probably also want to adjust the TCP stack in general to have more memory.

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Sometimes you'll need to setup a single point of authentification for e.g. to centralize stuff. 

I've found a nice Document, about Integrating Linux systems with Active Directory using Open Source Tools from 2017.

Redhat, Autor: Torsten Scherf

And an additional Link from Redhat with an interesstig post from Dmitri Pal from 2014.




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is about a locale issue during a foreman setup on CentOS 7.

locale environment variables were bad; continuing with LANG=C

In my case the output of locale -a showed en_US.utf8 but the output of env and the line line in /etc/locale.conf reads different.
en_US.UTF-8 which seams to be wrong or not translated correctly.
Long Story short, either export the correct settings or update the /etc/locales.conf file so that it read like this for example


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short but sweet

firewall-cmd --permanent --zone=public --add-service=http
firewall-cmd --permanent --zone=public --add-service=https
firewall-cmd --reload

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as a fix solution you can use google, as smtp relay for e.g. notifications. In this example I am working on a Fedora 27 Host.

Install needed packages

dnf -y install postfix mailx cyrus-sasl-plain

Restart and enable services

systemctl restart postfix && systemctl enable postfix

Adjust /etc/postfix/ depends your needs (marked in red)

myhostname =

relayhost = []:587
smtp_use_tls = yes
smtp_sasl_auth_enable = yes
smtp_sasl_password_maps = hash:/etc/postfix/sasl_passwd
smtp_tls_CAfile = /etc/ssl/certs/ca-bundle.crt
smtp_sasl_security_options = noanonymous
smtp_sasl_tls_security_options = noanonymous

Setup the secret

vim /etc/postfix/sasl_passwd
[]:587 username:password

Issue the command postmap to read the new secret

postmap /etc/postfix/sasl_passwd

Set correct owner and permissons

chown root:postfix /etc/postfix/sasl_passwd
chmod 640 /etc/postfix/sasl_passwd

Reload the service

systemctl reload postfix

Verify the setup, by sending you a Test Notification Mail

echo "Test Mail" | mail -s "Test Notification Mail"


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