Using version from GIT. When DHCP-Message-Type = 0 the server must not sending reply. But in this code set DHCP-Message-Type value from 0 to 1024 and reply sending to client.
src/main/dhcpd.c ... vp = pairfind(request->reply->vps, DHCP2ATTR(53)); /* DHCP-Message-Type */ if (vp) { request->reply->code = vp->vp_integer; if (request->reply->code < PW_DHCP_OFFSET) { request->reply->code += PW_DHCP_OFFSET; } } ... I think it must be something like this: if (vp) { request->reply->code = vp->vp_integer; if ((request->reply->code < PW_DHCP_OFFSET) && (request->reply->code != 0)) { request->reply->code += PW_DHCP_OFFSET; } } - List info/subscribe/unsubscribe? See http://www.freeradius.org/list/users.html