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Description of problem: According to the Networking Guide "The [DHCP] server, client and relay agents support both IPv4 and IPv6. However, the client and the server can only manage one protocol at a time — for dual support they must be started separately for IPv4 and IPv6" There is no documentation about how to correctly start DHCPv4 and DHCPv6 services on the SAME machine. This prevents users of adopting IPv6 on production systems. There is no documentation for specyfing DHCPv4 and DHCPv6 interfaces, if different on the same Red Hat system. Version-Release number of selected component (if applicable): Networking Guide for Red Hat Enterprise Linux 7 Beta, as of 21.12.2013. System Administrators Reference Guide for Red Hat Enterprise Linux 7 Beta, as of 21.12.2013 (for the /etc/sysconfig/dhcpd file) https://access.redhat.com/site/documentation/en-US/Red_Hat_Enterprise_Linux/7-Beta/html-single/Networking_Guide/index.html#s1-dhcp_for_ipv6_dhcpv6 https://access.redhat.com/site/documentation/en-US/Red_Hat_Enterprise_Linux/7-Beta/html-single/System_Administrators_Reference_Guide/index.html#sect-sysconfig-dhcpd How reproducible: Check https://access.redhat.com/site/documentation/en-US/Red_Hat_Enterprise_Linux/7-Beta/html-single/Networking_Guide/index.html#s1-dhcp_for_ipv6_dhcpv6 Check https://access.redhat.com/site/documentation/en-US/Red_Hat_Enterprise_Linux/7-Beta/html-single/System_Administrators_Reference_Guide/index.html#sect-sysconfig-dhcpd Actual results: There is no documentation about how to correctly start DHCPv4 and DHCPv6 services on the SAME Red Hat System. Expected results: Consistent documentation about how to correctly start DHCPv4 and DHCPv6 services on the SAME Red Hat System should exist.
Thank you Răzvan for raising this bug.
Created attachment 847198 [details] notes to Networking Guide 'Chapter 10. DHCP Servers' Hi Stephen, I've reviewed the 'Chapter 10. DHCP Servers' in Networking Guide and have few notes, see the attachment. The '2.1.5. /etc/sysconfig/dhcpd' section in System Administrators Reference Guide can be removed, see the attachment. Regarding the "please explain how to start DHCPv4 and DHCPv6 services on the SAME machine" request: If you want to run both DHCPv4 and DHCPv6 servers on one machine, simply configure and start them both, i.e. # vim /etc/dhcp/dhcpd6.conf # systemctl start dhcpd6 # vim /etc/dhcp/dhcpd.conf # systemctl start dhcpd
Hello and thanks, The main problem seems to be exactly the /etc/sysconfig/dhcpd file, so, IMHO, the section should be clarified, not removed. On a system with many network interfaces (multihomed), it's usually necessary to start the DHCP server on *some* interfaces only. For example, on a NAT Linux router/gateway + DHCP server, for a typical small office network, the DHCP server working for the private computers must be active on the LAN interface only, not toward the ISP (public network). In order to start the DHCP server on the correct interface (automatically, at boot), the /etc/sysconfig/dhcpd file *is* needed. Even more confusing, on a system providing both IPv4 and IPv6 addreses via DHCP, with simultaneous DHCPv4 and DHCPv6 processes, a mechanism is needed to clearly identify the network interfaces for *each* process. How can one specify all this in a single /etc/sysconfig/dhcpd file? Please explain... Thanks, Răzvan
Răzvan, /etc/sysconfig/dhcpd is not used anymore. Since dhcp-4.2.5-13 it contains the following comment: # If you are here to restrict what interfaces should dhcpd listen on, # be aware that dhcpd listens *only* on interfaces for which it finds subnet # declaration in dhcpd.conf. It means that explicitly enumerating interfaces # also on command line should not be required in most cases. # If you still insist on adding some command line options, # copy dhcpd.service from /lib/systemd/system to /etc/systemd/system and modify # it there. # https://fedoraproject.org/wiki/Systemd#How_do_I_customize_a_unit_file.2F_add_a_custom_unit_file.3F # example: # $ cp /usr/lib/systemd/system/dhcpd.service /etc/systemd/system/ # $ vi /etc/systemd/system/dhcpd.service # $ ExecStart=/usr/sbin/dhcpd -f -cf /etc/dhcp/dhcpd.conf -user dhcpd -group dhcpd --no-pid <your_interface_name(s)> # $ systemctl --system daemon-reload # $ systemctl restart dhcpd.service The same is true also for dhcpd6.service and Stephen is currently working on the documentation.
As the chapter has passed review I will close this as "current release".