DHCP Server for Windows » settings

IgnoreRequestedAddress

uwe — Tue, 17 Sep 2024 07:12:33 +0000

Changes how the DHCP Server interprets the requested address submitted from a client.

[Settings]
IgnoreRequestedAddress=1        ; Default: 0 (don't ignore)

If IgnoreRequestedAddress is set to 0 (default): The DHCP server will take the requested address from an unknown client into account when selecting an address to offer, matching the requested address as long as it is free and inside the IP pool.

If IgnoreRequestedAddress is set to 1: The DHCP server will ignore unknown clients suggestion on IP address. Leading to the DHCP server not taking the client request for a specific IP address in account when selection an address to offer the client.

This behavior might not be fully confirmative with the DHCP specification and is not recommended in general usage. But might be useful in special cases.

This feature was an added in V2.10.0.0.

BalloonTimeFormat

uwe — Tue, 01 Mar 2022 06:43:12 +0000

Specifies the time and date format used in balloon messages. The default is %b %d, %H:%M.

[Settings]
BalloonTimeFormat=        ; Default: %b %d, %H:%M

This feature was an added in V2.9.2.0.
The format supports the following (strftime style) sepcifications:

%a	Abbreviated weekday name
%A	Full weekday name
%b	Abbreviated month name
%B	Full month name
%c	Date and time representation appropriate for locale
%d	Day of month as decimal number (01 – 31)
%H	Hour in 24-hour format (00 – 23)
%I	Hour in 12-hour format (01 – 12)
%j	Day of year as decimal number (001 – 366)
%m	Month as decimal number (01 – 12)
%M	Minute as decimal number (00 – 59)
%p	Current locale’s A.M./P.M. indicator for 12-hour clock
%S	Second as decimal number (00 – 59)
%U	Week of year as decimal number, with Sunday as first day of week (00 – 53)
%w	Weekday as decimal number (0 – 6; Sunday is 0)
%W	Week of year as decimal number, with Monday as first day of week (00 – 53)
%x	Date representation for current locale
%X	Time representation for current locale
%y	Year without century, as decimal number (00 – 99)
%Y	Year with century, as decimal number
%z, %Z	Time-zone name or abbreviation; no characters if time zone is unknown
%%	Percent sign

Specify an empty BalloonTimeFormat=, in case no timestamp shall be shown in the balloon message.

SyncServer

uwe — Mon, 31 Aug 2020 07:07:49 +0000

Specifies the other DHCP server to load data from. This is a new feature in V2.9 and allows to setup redundant configurations for DNS. The idea is when you setup the split scope redundancy, as described in the FAQ, then you need to handle local DNS requests. See the FAQ for more information.

[Settings]
SyncServer=other-server:80  ; load data from other-server

In order for this to work you need to configure the HTTP function on the other server. IP addresses or names are allowed optionally followed by a colon and the port number of the server.

ReceiveWindow

uwe — Sat, 16 Nov 2019 07:22:36 +0000

Specifies the size of the windows UDP receive buffer in KBytes. The default is 64, which should be enough to allow 256 clients to request an IP address at the same time. It should only be necessary to change this in very rare cases.

[Settings]
ReceiveWindow=8        ; Default: 64 [KBytes]

This feature was an added in V2.7.

TraceFileMaxSize

uwe — Fri, 27 Oct 2017 05:19:16 +0000

Specifies the maximum size of the trace file (dhcptrc.txt) See also Trace. Once the trace file reached the specified limit in size, it is copied to dhcptrc.bak and a new trace file is created.

[Settings]
TraceFileMaxSize=256000        ; Default: 128000

This feature was an added in V2.6.0.

ReadOnly

uwe — Fri, 27 Oct 2017 05:16:02 +0000

When ReadOnly is set to 1, then no changes to the INI file will be made by the DHCP server. All newly recognized clients will get an IP address assigned but the respective client entry is not created. Which has the effect that the same IP address will be used next time for another client! This might be useful for test labs, that test one device after the other and explicitly want to assign the same IP address to each one.

[Settings]
ReadOnly=1        ; Default: 0

This feature was an added in V2.6.0.

DeleteClientsFromWrongIndex

uwe — Fri, 27 Oct 2017 05:10:39 +0000

All newly created clients will get an entry in the client section Index=n where n is the number of the IPBIND_n. If the same client tries to acquire a new IP address but from a different IPBIND_k interface then the software will recognize that n != k meaning the client section is created from a different IPBIND. In that situation and when DeleteClientsFromWrongIndex is 1, then DHCP server will delete the client entry and create a new one. Please keep in mind that this will work only, when the client section includes the Index=n entry which is only the case after the client has been acquiring a new lease.

[Settings]
DeleteClientsFromWrongIndex=1        ; Default: 0

This feature was an added in V2.6.0.

ReserveByOffer

uwe — Sun, 13 Sep 2015 08:33:18 +0000

Controls the behavior of the DHCP Server when offering an IP address to the client. In case of ReserveByOffer=1, the client section is written to the INI file with a lease time of 1 second when answering with a DHCPOFFER message. In case of 0, no INI file entry is made at the time of offering an IP address. Only the actual assignment (reaction to DHCPREQUEST) of the IP address creates a client section. Of course, the lease time is updated upon assignment to the requested lease time.

[Settings]
ReserveByOffer=0          ; Default: 1

This was an undocumented feature until V2.5.0.

VENDORCLASS

uwe — Sat, 06 Sep 2014 16:37:43 +0000

Configure a VENDORCLASS.

[Settings]
VENDORCLASS=MSFT 5.0          ; Default: -

If a VENDORCLASS is specified as an entry in the [Settings] section, then only clients with the same vendor class defined in their DHCP request get an IP address assigned.

Trace

uwe — Sat, 06 Sep 2014 16:35:39 +0000

Enabling the Trace.

[Settings]
Trace=1          ; Default: 0
TraceFile=c:\temp\dhcptrc.txt

You can switch the trace on by putting a Trace=1 entry into the [Settings] section. The trace file is called dhcptrc.txt and is written into the same folder as the dhcpsrv.exe and the dhcpsrv.ini files. I recommend to switch the trace on, if you encounter any problems and attach the trace file to the e-mail that you are sending to me to report it. If you want the trace to have a different name (and/or directory) then use TraceFile for that. Example:

[Settings]
Trace=1  ; 1= enable,  0=disable
TraceFile=c:\temp\dhcptrc.txt  ; this is where the trace goes

If the TraceFile setting in not set then the default is dhcptrc.txt in the dhcpsrv.exe directory. TraceFile is a new feature in V1.5.2. Since V2.7 you may also use a relative path to specifiy the trace file name. Relative paths are interpreted relative to the INI file location.