Category: Networking

Use TCP wrappers with care

Real life story.   DMZ based server dedicated to SFTP was configured with sshd rules in /etc/hosts.allow sshd : ALL@16.89.97.*:ALLOW sshd : ALL@14.251.*:ALLOW sshd : AAL@208.94.61.*:ALLOW Should have been: sshd : ALL@16.89.97.*:ALLOW sshd : ALL@14.251.*:ALLOW sshd : ALL@208.94.61.*:ALLOW That network was the firewall to the outside world. The end users were inconvenienced and the firewall […]

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DNS configuration checklist

BIND has always been a dark art. Recent configuration nuances made in the name of improving security have made things all the more fun. Here is a simple checklist that can avoid trouble and downed websites. Note that on RHEL6/CentOS/ and clones the /var/named/chroot structure has been made obsolete. Before starting cp /etc/named.conf /root  # […]

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Network Channel Bonding (teaming) RHEL 6.0

This procedure did not actually change very much from RHEL 5.0. Knowing the changes however are pretty critical to getting it right. Gone is the Administrator’s friend and potential cestpool, /etc/modpprobe.conf Its replaced by anything you want to load in /etc/modprobe.d Naming guidelines? Who needs them. Name the file anything you want. Procedure: Still pretty […]

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