IPv6 Transition on Red Hat Linux

With IPv4 address exhaustion accelerating, organizations running Red Hat-based distributions need a smooth transition to IPv6. Zwiegnet specializes in configuring dual-stack and IPv6-only networking on AlmaLinux, Rocky Linux, Oracle Linux, and RHEL using industry-standard tools like NetworkManager (nmcli).

Our Red Hat IPv6 Services Include

• Dual-Stack Setup – Run IPv4 and IPv6 simultaneously for maximum compatibility.
• IPv6-Only Deployments – Pure IPv6 with optional NAT64/DNS64 for legacy IPv4 access.
• Static IPv6 Configuration – Using nmcli or ifcfg files with proper prefix delegation.
• Firewall Hardening – firewalld rules for both IPv4 and IPv6 (rich rules or direct ip6tables).
• Service IPv6 Enablement – Make Apache, Nginx, PostgreSQL, Postfix, LDAP, Kerberos, and DNS listen on IPv6.
• sysctl Tuning & Security – Privacy extensions, forwarding, accept_ra, and best practices.
• Testing & Validation – Connectivity, performance, and fallback testing.

Dual-Stack Configuration Example (nmcli – Recommended on RHEL 9 / AlmaLinux 9 / Rocky Linux 9)

# Replace "ens192" with your actual interface name (check with nmcli device)
sudo nmcli connection modify "ens192" ipv4.method manual \
    ipv4.addresses "192.0.2.10/24" \
    ipv4.gateway "192.0.2.1"

sudo nmcli connection modify "ens192" ipv6.method manual \
    ipv6.addresses "2001:db8:1234::10/64" \
    ipv6.gateway "2001:db8:1234::1" \
    ipv6.dns "2001:4860:4860::8888"

# Apply changes
sudo nmcli connection up "ens192"

# Verify
ip -4 addr show ens192
ip -6 addr show ens192

Making Services IPv6-Ready on Red Hat Linux

Many services listen on IPv6 by default once the OS has an IPv6 address, but some require explicit configuration:

• Apache (httpd) – Usually automatic. Add or ensure: Listen [::]:80 and Listen [::]:443 in /etc/httpd/conf/httpd.conf or ssl.conf. Restart: systemctl restart httpd
• Nginx – Add listen [::]:80; and listen [::]:443 ssl; in your server blocks. Reload: nginx -s reload
• PostgreSQL – Edit postgresql.conf: listen_addresses = '*'. Update pg_hba.conf to allow IPv6 connections (e.g., host all all ::/0 md5). Restart PostgreSQL.
• Postfix – Default is usually inet_protocols = all. For IPv6-only: postconf -e "inet_protocols = ipv6". Then postfix reload.
• OpenLDAP – Ensure olcListen or /etc/openldap/slapd.d includes IPv6. Common: ldap://[::]:389 and ldaps://[::]:636.
• Kerberos (krb5) – Add IPv6 addresses to kdc lines in krb5.conf and ensure the KDC listens on IPv6.
• BIND (DNS) – In named.conf: listen-on-v6 { any; };. Restart named.

We also configure firewalld to allow the necessary IPv6 traffic:

sudo firewall-cmd --permanent --add-service=http --add-service=https
sudo firewall-cmd --permanent --add-port=5432/tcp   # PostgreSQL example
sudo firewall-cmd --reload

Located between Madison and Milwaukee, Wisconsin since 2009 — hands-on Red Hat Linux expertise with real-world IPv6 transition experience.