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- 'ignore client-updates;' now has behaviour that is different from
'deny client-updates;'. The client's request is not truly ignored, rather it is encouraged. Should this value be configured, the server updates DNS as though client-updates were set to 'deny'. That is, it enters into DNS whatever it is configured to do already, provided it is configured to. Then it sends a response to the client that lets the client believe it is performing client updates (which it will), probably for a different name. In essence, this lets the client do as it will, ignoring this aspect of their request. [ISC-Bugs #16185]
This commit is contained in:
David Hankins
parent
567e85616c
commit
a396d25fba
10
RELNOTES
10
RELNOTES
@ -133,6 +133,16 @@ and for prodding me into improving it.
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increased from 16 to 128. This is intended to match Microsoft Windows
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DHCP Client behaviour, to increase compatibility.
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- 'ignore client-updates;' now has behaviour that is different from
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'deny client-updates;'. The client's request is not truly ignored,
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rather it is encouraged. Should this value be configured, the server
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updates DNS as though client-updates were set to 'deny'. That is, it
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enters into DNS whatever it is configured to do already, provided it is
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configured to. Then it sends a response to the client that lets the
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client believe it is performing client updates (which it will), probably
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for a different name. In essence, this lets the client do as it will,
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ignoring this aspect of their request.
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Changes since 3.0.4
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- A warning that host statements declared within subnet or shared-network
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121
server/ddns.c
121
server/ddns.c
@ -34,7 +34,7 @@
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#ifndef lint
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static char copyright[] =
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"$Id: ddns.c,v 1.20 2006/07/19 17:14:55 dhankins Exp $ Copyright (c) 2004-2005 Internet Systems Consortium. All rights reserved.\n";
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"$Id: ddns.c,v 1.21 2006/07/19 20:13:57 dhankins Exp $ Copyright (c) 2004-2005 Internet Systems Consortium. All rights reserved.\n";
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#endif /* not lint */
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#include "dhcpd.h"
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@ -232,7 +232,7 @@ int ddns_updates (struct packet *packet,
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isc_result_t rcode1 = ISC_R_SUCCESS, rcode2 = ISC_R_SUCCESS;
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int server_updates_a = 1;
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struct buffer *bp = (struct buffer *)0;
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int ignorep = 0;
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int ignorep = 0, client_ignorep = 0;
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if (ddns_update_style != 2)
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return 0;
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@ -252,10 +252,8 @@ int ddns_updates (struct packet *packet,
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record, see if the client wants to update its own A record. */
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if (!(oc = lookup_option(&server_universe, state->options,
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SV_CLIENT_UPDATES)) ||
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evaluate_boolean_option_cache (&ignorep, packet, lease,
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(struct client_state *)0,
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packet -> options,
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state -> options,
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evaluate_boolean_option_cache(&client_ignorep, packet, lease, NULL,
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packet->options, state->options,
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&lease->scope, oc, MDL)) {
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/* If there's no fqdn.no-client-update or if it's
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nonzero, don't try to use the client-supplied
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@ -589,14 +587,101 @@ int ddns_updates (struct packet *packet,
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&ddns_rev_name);
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}
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/* Set up the outgoing FQDN option if there was an incoming
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FQDN option. If there's a valid FQDN option, there should
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be an FQDN_ENCODED suboption, so we test the latter to
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detect the presence of the former. */
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noerror:
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if ((oc = lookup_option (&fqdn_universe,
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packet -> options, FQDN_ENCODED))
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&& buffer_allocate (&bp, ddns_fwd_name.len + 5, MDL)) {
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/* If we're ignoring client updates, then we tell a sort of 'white
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* lie'. We've already updated the name the server wants (per the
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* config written by the server admin). Now let the client do as
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* it pleases with the name they supplied (if any).
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*
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* We only form an FQDN option this way if the client supplied an
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* FQDN option that had FQDN_SERVER_UPDATE set false.
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*/
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if (client_ignorep &&
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(oc = lookup_option(&fqdn_universe, packet->options,
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FQDN_SERVER_UPDATE)) &&
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!evaluate_boolean_option_cache(&ignorep, packet, lease, NULL,
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packet->options, state->options,
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&lease->scope, oc, MDL)) {
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oc = lookup_option(&fqdn_universe, packet->options, FQDN_FQDN);
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if (oc && evaluate_option_cache(&d1, packet, lease, NULL,
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packet->options, state->options,
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&global_scope, oc, MDL)) {
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if (d1.len == 0 ||
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!buffer_allocate(&bp, d1.len + 5, MDL))
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goto badfqdn;
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/* Server pretends it is not updating. */
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bp->data[0] = 0;
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if (!save_option_buffer(&fqdn_universe, state->options,
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bp, &bp->data[0], 1,
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&fqdn_options[FQDN_SERVER_UPDATE],
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0))
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goto badfqdn;
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/* Client is encouraged to update. */
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bp->data[1] = 0;
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if (!save_option_buffer(&fqdn_universe, state->options,
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bp, &bp->data[1], 1,
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&fqdn_options[FQDN_NO_CLIENT_UPDATE],
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0))
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goto badfqdn;
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/* Use the encoding of client's FQDN option. */
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oc = lookup_option(&fqdn_universe, packet->options,
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FQDN_ENCODED);
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if (oc && evaluate_boolean_option_cache(&ignorep,
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packet, lease, NULL,
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packet->options,
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state->options,
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&lease->scope, oc,
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MDL))
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bp->data[2] = 1; /* FQDN is encoded. */
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else
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bp->data[2] = 0; /* FQDN is not encoded. */
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if (!save_option_buffer(&fqdn_universe, state->options,
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bp, &bp->data[2], 1,
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&fqdn_options[FQDN_ENCODED], 0))
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goto badfqdn;
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/* Current FQDN drafts indicate 255 is mandatory. */
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bp->data[3] = 255;
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if (!save_option_buffer(&fqdn_universe, state->options,
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bp, &bp->data[3], 1,
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&fqdn_options[FQDN_RCODE1], 0))
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goto badfqdn;
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bp->data[4] = 255;
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if (!save_option_buffer(&fqdn_universe, state->options,
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bp, &bp->data[4], 1,
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&fqdn_options[FQDN_RCODE2], 0))
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goto badfqdn;
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/* Copy in the FQDN supplied by the client. Note well
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* that the format of this option in the cache is going
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* to be in text format. If the fqdn supplied by the
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* client is encoded, it is decoded into the option
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* cache when parsed out of the packet. It will be
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* re-encoded when the option is assembled to be
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* transmitted if the client elects that encoding.
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*/
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memcpy(&bp->data[5], d1.data, d1.len);
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if (!save_option_buffer(&fqdn_universe, state->options,
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bp, &bp->data[5], 1,
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&fqdn_options[FQDN_FQDN], 0))
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goto badfqdn;
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data_string_forget(&d1, MDL);
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}
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/* Set up the outgoing FQDN option if there was an incoming
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* FQDN option. If there's a valid FQDN option, there MUST
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* be an FQDN_SERVER_UPDATES suboption, it's part of the fixed
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* length head of the option contents, so we test the latter
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* to detect the presence of the former.
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*/
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} else if ((oc = lookup_option(&fqdn_universe, packet->options,
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FQDN_ENCODED)) &&
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buffer_allocate(&bp, ddns_fwd_name.len + 5, MDL)) {
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bp -> data [0] = server_updates_a;
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if (!save_option_buffer (&fqdn_universe, state -> options,
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bp, &bp -> data [0], 1,
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@ -607,13 +692,10 @@ int ddns_updates (struct packet *packet,
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bp, &bp -> data [1], 1,
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FQDN_NO_CLIENT_UPDATE, 0))
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goto badfqdn;
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/* Do the same encoding the client did. */
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oc = lookup_option (&fqdn_universe, packet -> options,
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FQDN_ENCODED);
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if (oc &&
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evaluate_boolean_option_cache (&ignorep, packet, lease,
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(struct client_state *)0,
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packet -> options,
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if (evaluate_boolean_option_cache(&ignorep, packet, lease,
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NULL, packet->options,
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state->options,
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&lease->scope, oc, MDL))
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bp -> data [2] = 1;
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@ -649,6 +731,7 @@ int ddns_updates (struct packet *packet,
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/*
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* Final cleanup.
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*/
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data_string_forget(&d1, MDL);
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data_string_forget(&ddns_hostname, MDL);
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data_string_forget(&ddns_domainname, MDL);
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data_string_forget(&old_ddns_fwd_name, MDL);
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@ -28,7 +28,7 @@
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.\" see ``http://www.vix.com''. To learn more about Nominum, Inc., see
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.\" ``http://www.nominum.com''.
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.\"
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.\" $Id: dhcpd.conf.5,v 1.76 2006/07/19 17:14:55 dhankins Exp $
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.\" $Id: dhcpd.conf.5,v 1.77 2006/07/19 20:13:57 dhankins Exp $
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.\"
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.TH dhcpd.conf 5
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.SH NAME
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@ -1138,6 +1138,12 @@ name in the fqdn option, the server uses only the leftmost part of the
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domain name - in the example above, "jschmoe" instead of
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"jschmoe.radish.org".
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.PP
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Further, if the \fIignore client-updates;\fR directive is used, then
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the server will in addition send a response in the DHCP packet, using
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the FQDN Option, that implies to the client that it should perform its
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own updates if it chooses to do so. With \fIdeny client-updates;\fR, a
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response is sent which indicates the client may not perform updates.
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.PP
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Also, if the
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.I use-host-decl-names
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configuration option is enabled, then the host declaration's
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