DHCPv6 Server
What is Port 547?
Port 547 is the server port for DHCPv6, where DHCPv6 servers and relay agents listen for client requests. When an IPv6 client needs configuration, it sends a Solicit message to the All_DHCP_Relay_Agents_and_Servers multicast address (ff02::1:2) with a destination port of 547. The server responds from port 547 to the client's port 546. DHCPv6 relay agents also use port 547 to forward client messages to servers on different network segments. The protocol supports four main message types: Solicit, Advertise, Request, and Reply, similar to DHCP's DORA process. DHCPv6 prefix delegation (DHCPv6-PD) is particularly important for ISPs to assign IPv6 prefixes to customer routers.
Common Uses
- Serving IPv6 address configurations to network clients
- IPv6 prefix delegation to downstream routers
- DHCPv6 relay for multi-segment networks
- Centralized IPv6 address policy enforcement
Technical Details
Copy-paste commands to check port 547 (DHCPv6 Server) from your terminal
Test connectivity
nmap -p 547 -sU -sV example.com
(echo > /dev/tcp/example.com/547) 2>/dev/null && echo "open" || echo "closed"
Open port in firewall
sudo ufw allow 547/udp
sudo iptables -A INPUT -p udp --dport 547 -j ACCEPT
sudo firewall-cmd --permanent --add-port=547/udp && sudo firewall-cmd --reload
Security Considerations
Protect DHCPv6 servers with DHCPv6 snooping and RA guard on switches. Rogue DHCPv6 servers can redirect traffic and perform man-in-the-middle attacks. Use network segmentation to isolate the DHCP infrastructure. Monitor for unauthorized DHCPv6 responses on the network. Implement logging for all address assignments.
Popular Ports Reference
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