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@@ -0,0 +1,85 @@ +odhcpd - Embedded DHCP/DHCPv6/RA Server & Relay + +** Abstract ** + +odhcpd is a daemon for serving and relaying IP management protocols to +configure clients and downstream routers. It tries to follow the RFC 6204 +requirements for IPv6 home routers. + +odhcpd provides server services for DHCP, RA, stateless and stateful DHCPv6, +prefix delegation and can be used to relay RA, DHCPv6 and NDP between routed +(non-bridged) interfaces in case no delegated prefixes are available. + + +** Features ** + +1. Router Discovery support (solicitations and advertisements) with 2 modes + server: RD server for slave interfaces + a) automatic detection of prefixes, delegated prefix and default routes, MTU + b) automatic reannouncement when changes to prefixes or routes occur + + relay: RD relay between master and slave interfaces + a) support for rewriting announced DNS-server addresses in relay mode + +3. DHCPv6-support with 2 modes of operation + server: minimalistic server mode + a) stateless and stateful address assignment + b) prefix delegation support + c) dynamic reconfiguration in case prefixes change + d) hostname detection and hosts-file creation + + relay: mostly standards-compliant DHCPv6-relay + a) support for rewriting announced DNS-server addresses + +4. Proxy for Neighbor Discovery messages (solicitations and advertisments) + a) support for auto-learning routes to the local routing table + b) support for marking interfaces "external" not proxying NDP for them + and only serving NDP for DAD and for traffic to the router itself + [Warning: you should provide additional firewall rules for security] + + +** Compiling ** + +odhcpd uses cmake: +* To prepare a Makefile use: "cmake ." +* To build / install use: "make" / "make install" afterwards. +* To build DEB or RPM packages use: "make package" afterwards. + + +** Server Mode ** + +0. Server mode is used as a minimalistic alternative for full-blown servers + like radvd or ISC DHCP if simplicity or a small footprint matter. + Note: The master interface is unused in this mode. It should be set to '.'. + +1. If there are non-local addresses assigned to the slave interface when a + router solicitation is received, said prefixes are announced automatically + for stateless autoconfiguration and also offered via stateful DHCPv6. + If all prefixes are bigger than /64 all but the first /64 of these prefixes + is offered via DHCPv6-PD to downstream routers. + +2. If DNS servers should be announced (DHCPv6 server-mode) then a local DNS- + proxy (e.g. dnsmasq) needs to be run on the router itself because 6relayd + will always announce a local address as DNS-server (if not otherwise + configured). + +3. odhcpd is run with the appropriate configuration. + + +** Relay Mode ** + +0. Relay mode is used when a /64-bit IPv6-Prefix should be distributed over + several links / isolated layer 2 domains (e.g. if no prefix delegation + is available). In this mode NDP (namely Router Discovery and Neighbor + Discovery) messages and DHCPv6-messages are proxied. For DHCPv6 also + server mode can be used instead of relaying if desired. + +1. When starting 6relayd it is required that the master interface - where + IPv6-service is already provided - is configured and usable. + +2. If the upstream router doesn't provide or announce a DNS-service that is + reachable in an at least site-local scope, a local DNS proxy (e.g. dnsmasq) + needs to be run and configued on the same router where 6relayd is running. + (This step can most likely be skipped in most environments.) + +3. odhcpd is run with the appropriate configuration. |