The permission errors we're seeing stem from BIND's inability to create and modify journal files (.jnl) during dynamic DNS updates. The key symptoms appear in syslog:

Nov 12 08:00:53 ps133045 named[14314]: /etc/bind/zones/mydomain.com.zone.jnl: create: permission denied
Nov 12 08:00:53 ps133045 named[14314]: client 78.72.53.42#50135: updating zone 'mydomain.com/IN': error: journal open failed

Common mistakes include:

• Incorrect directory ownership (needs bind:bind)
• Wrong permission bits (directories need execute bit)
• SELinux/AppArmor restrictions (often overlooked)

Here's the correct setup:

# Directory structure
sudo chown -R bind:bind /etc/bind/zones
sudo chmod -R 775 /etc/bind/zones
sudo chmod g+s /etc/bind/zones  # Set SGID bit

# For journal files
touch /etc/bind/zones/mydomain.com.zone.jnl
chown bind:bind /etc/bind/zones/mydomain.com.zone.jnl
chmod 664 /etc/bind/zones/mydomain.com.zone.jnl

Ensure your named.conf includes proper update policies:

zone "mydomain.com" {
    type master;
    file "/etc/bind/zones/mydomain.com.zone";
    allow-update { key "www.mydomain.com"; };
    journal "/etc/bind/zones/mydomain.com.zone.jnl";
};

When basic permission fixes don't work:

# Check if SELinux is blocking:
sudo ausearch -m avc -ts recent

# Or for AppArmor:
sudo aa-status
sudo journalctl -u apparmor --no-pager | grep named

# Temporary test:
sudo setenforce 0  # For SELinux
sudo systemctl stop apparmor  # For AppArmor

Here's a complete remediation script:

#!/bin/bash
# Fix BIND permissions
ZONE_DIR="/etc/bind/zones"
ZONE_FILE="mydomain.com.zone"

sudo systemctl stop named
sudo chown -R bind:bind $ZONE_DIR
sudo chmod -R 775 $ZONE_DIR
sudo chmod g+s $ZONE_DIR
sudo touch $ZONE_DIR/$ZONE_FILE.jnl
sudo chown bind:bind $ZONE_DIR/$ZONE_FILE.jnl
sudo chmod 664 $ZONE_DIR/$ZONE_FILE.jnl
sudo restorecon -Rv $ZONE_DIR  # For SELinux
sudo systemctl start named

Test with nsupdate:

nsupdate -k Kwww.mydomain.com.+157.17183.key <<EOF
server ns1.mydomain.com
zone mydomain.com
update add test.mydomain.com 300 A 192.168.1.1
send
EOF

Check logs for success messages. Properly configured systems should show:

client x.x.x.x#port: updating zone 'mydomain.com/IN': update successful

When working with BIND and nsupdate for dynamic DNS updates, the most common roadblock developers face is permission-related errors. The log entries clearly show the named daemon is failing to create/modify journal files and configuration files:

Nov 12 08:00:53 ps133045 named[14314]: /etc/bind/zones/mydomain.com.zone.jnl: create: permission denied
Nov 12 08:40:10 ps133045 named[21169]: /etc/bind/named.conf.local:9: open: /var/named/dnskeys.conf: permission denied

The key misconception in the original setup was applying 666 permissions indiscriminately. Here's the correct approach:

# Directory structure should have execute permissions
chmod 775 /etc/bind
chmod 775 /var/named

# Zone files should be readable by bind group
chown root:bind /etc/bind/zones/mydomain.com.zone
chmod 640 /etc/bind/zones/mydomain.com.zone

# Journal files need proper ownership
chown bind:bind /etc/bind/zones/mydomain.com.zone.jnl
chmod 660 /etc/bind/zones/mydomain.com.zone.jnl

Modern Linux systems often have additional security layers that might block BIND operations:

# For AppArmor (Ubuntu/Debian):
sudo aa-complain /etc/apparmor.d/usr.sbin.named

# For SELinux (RHEL/CentOS):
sudo chcon -R -t named_zone_t /etc/bind/zones/
sudo restorecon -Rv /var/named

Here's a properly configured named.conf.local snippet for dynamic updates:

zone "mydomain.com" {
    type master;
    file "/etc/bind/zones/mydomain.com.zone";
    allow-update { key "www.mydomain.com"; };
    journal "/etc/bind/zones/mydomain.com.zone.jnl";
};

include "/var/named/dnskeys.conf";

When testing updates, use this verbose nsupdate command:

nsupdate -k Kwww.mydomain.com.+157.17183.key -v
> server ns1.mydomain.com
> zone mydomain.com
> update add test.mydomain.com. 300 A 192.168.1.1
> send
> quit

Check the journal file status immediately after:

ls -la /etc/bind/zones/mydomain.com.zone.jnl
journalprint -j /etc/bind/zones/mydomain.com.zone.jnl