Dhcpd.leases(5): dhcp client lease database - linux man page

the Lease Declaration
the Failover Peer Condition Declaration
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Lease descriptions are kept in a format that’s parsed through the same recursive descent parser used

to see the dhcpd.conf(5) and dhclient.conf(5) files. Lease files can contain lease declarations, as well as group and subgroup

declarations, host declarations and failover condition declarations. Group, subgroup and host declarations are utilized to record objects produced while using OMAPI

protocol.

The lease file is really a log-structured file – each time a lease changes, the items in that lease are written towards the finish from the file. Which means that it’s

possible and quite cost effective for there to become several declarations of the identical lease within the lease file simultaneously. For the reason that situation, the

demonstration of that specific lease that seems last within the file is the one which is within effect.

Group, subgroup and host declarations within the lease file are handled very much the same, with the exception that if these objects are deleted, a rubout is

written towards the lease file. This really is likewise declaration, with within the scope from the declaration. Once the lease file is re-written, any

such rubouts that may be eliminated are eliminated. You’ll be able to delete a declaration within the dhcpd.conf file within this situation, the rubout can’t ever be

eliminated in the dhcpd.leases file.

the Lease Declaration

lease ip-address

Each lease declaration includes the only Ip that’s been leased towards the client. The statements inside the braces define the time period of the

lease and also to whom it’s assigned.

starts dateends datetstp datetsfp dateatsfp datecltt dateThe beginning and finish duration of a lease are recorded while using starts and ends statements. The tstp statement is specified when the failover protocol has been

used, and signifies what time the peer continues to be told the lease expires. The tsfp statement can also be specified when the failover protocol has been used, and

signifies the lease expiry time the peer has acknowledged. The atsfp statement may be the actual time sent in the failover partner. The cltt statement is

the client’s last transaction time.

The date is specified by two ways, with respect to the configuration value for that db-time-format parameter. Whether it was set to default,

then your date fields appear the following:

week day year/month/day hour:minute:second

The week day exists to allow an individual to inform whenever a lease expires – it’s specified like a number from zero to 6, with zero being Sunday. The

day’s week is overlooked on input. The entire year is specified using the century, therefore it should generally be four digits aside from really lengthy leases. The month is

specified like a number beginning with 1 for The month of january. Your day from the month is specified beginning with 1. The hour is really a number between and 23, the

minute several between and 59, and also the second additionally a number between and 59.

Lease occasions are specified by Universal Coordinated Time (UTC), away from the local time zone. There’s most likely nowhere on the planet in which the occasions recorded

on the lease will always be just like wall clock occasions. Of all unix machines, you are able to display the present amount of time in UTC by typing date -u.

When the db-time-format was configured to local, then your date fields appear the following:

epoch #

The seconds-since-epoch is really as based on the system’s local clock (frequently known as “unix time”). The # symbol offers a comment that

describes what actual time this is because based on the system’s configured timezone, at that time the worth was written. It’s provided just for human

inspection.

If your lease won’t ever expire, date is never rather of the actual date.

hardware hardware-type mac-address

The hardware statement records the MAC address from the network interface which the lease is going to be used. It’s specified as a number of hexadecimal octets,

separated by colons.

uid client-identifier

The uid statement records the customer identifier utilized by the customer to get the lease. Customers are not needed to transmit client identifiers, and

this statement only seems when the client did actually send one. Client identifiers are usually an ARP type (1 for ethernet) adopted through the MAC address, just

as with the hardware statement, but this isn’t needed.

The customer identifier is recorded like a colon-separated hexadecimal list or like a quoted string. If it’s recorded like a quoted string also it contains

a number of non-printable figures, individuals figures are symbolized as octal escapes – a backslash character adopted by three octal digits.

client-hostname “hostname“

Most DHCP clients will be sending their hostname within the host-name option. If your client transmits its hostname in this manner, the hostname is documented on the lease

having a client-hostname statement. This isn’t needed through the protocol, however, a lot of specialized DHCP clients don’t send a number-name option.

abandoned

The abandoned statement signifies the DHCP server has abandoned the lease. For the reason that situation, the abandoned statement will be employed to indicate

the lease shouldn’t be reassigned. Please visit the dhcpd.conf(5) manual page for details about abandoned leases.

binding condition condition next binding condition condition

The binding condition statement declares the lease’s binding condition. Once the DHCP server isn’t configured to make use of the failover protocol, a lease’s

binding condition is going to be either active or free. The failover protocol adds extra transitional states, along with the backup condition,

which signifies the lease can be obtained for allocation through the failover secondary.

The next binding condition statement signifies what condition the lease will proceed to once the current condition expires. Time once the current condition expires

is specified by the ends statement.

option agent.circuit-id string option agent.remote-id string

The option agent.circuit-id and option agent.remote-id statements are utilized to record the circuit ID and remote ID options send through the relay

agent, when the relay agent uses the relay agent information option. This enables these options for use consistently in conditional evaluations even

once the client is contacting the server directly instead of through its relay agent.

set variable = value

The set statement sets the need for a flexible around the lease. For general info on variables, begin to see the dhcp-eval(5) manual page.

The ddns-text variable

The ddns-text variable can be used to record the need for the client’s TXT identification record once the interim ddns update style has been utilized

to update the DNS for the lease.

The ddns-fwd-name variable

The ddns-fwd-name variable records the need for the name utilized in updating the client’s An archive if your DDNS update continues to be effectively made by the

server. The server might also used this name to update the client’s PTR record.

The ddns-client-fqdn variable

When the server is configured to make use of the interim ddns update style, and it is configured to permit clients to update their very own fqdns, and also the client did

actually update its very own fqdn, then your ddns-client-fqdn variable records the name the client has indicated it’s using. This is actually the name that

the server may have accustomed to update the client’s PTR record within this situation.

The ddns-rev-name variable

When the server effectively updates the client’s PTR record, this variable will record the name the DHCP server employed for the PTR record. The name to

that the PTR record points is going to be either the ddns-fwd-name or even the ddns-client-fqdn.

on occasions The on statement records a summary of statements to complete if your certain event occurs. The potential occasions

that may occur to have an active lease are release and expiry. Several event could be specified – if that’s the case, the occasions are

separated by ” figures.

bootp reserved Both of these statements are effectively flags. If there are any, they indicate the BOOTP and RESERVED failover flags,

correspondingly, ought to be set. BOOTP and RESERVED dynamic leases are treated differently than usual dynamic leases, because they may be utilised by the customer to

that they are presently allotted.

the Failover Peer Condition Declaration

The condition associated with a failover peering plans can also be recorded within the

lease file, while using failover peer statement:

failover peer “name” condition condition condition at datepeer condition condition at

dateThe states from the peer named name has been recorded. Both condition from the running server (my condition) and yet another failover partner (peer

condition) are recorded. The next states are possible: unknown-condition, partner-lower, normal, communications-interrupted,

resolution-interrupted, potential-conflict, recover, recover-done, shutdown, stopped, and startup.

/var/lib/dhcpd/dhcpd.leases