Logging DHCP lease duration in seconds

[Denis Laventure]

The client will renew the lease at half the max-lease-time. So seeing 150 sec for a 300 sec lease seems normal.

Hi,

I have an easy question I believe, I want to log DHCP lease durations given to clients, I tried the following, however it appears most of the time, logs are showing half of the lease duration.

log(info, concat( "IP: ", binary-to-ascii(10, 8, ".", leased-address), " ; ", "leasetime:", binary-to-ascii(10,32,"",encode-int(lease-time,32)) ));

I have set the following lease time values for a pool:

subnet 172.16.2.0 netmask 255.255.255.0 {
  option routers 172.16.2.1;
  pool {
    failover peer "failover-partner";
    default-lease-time 300;
    min-lease-time 300;
    max-lease-time 300;
    range 172.16.2.10 172.16.2.250;
  }
}

And this configuration produces an output like this:

Oct  2 14:34:44 mercan dhcpd: IP: 172.16.2.127 ; leasetime:155
Oct  2 14:37:10 mercan dhcpd: IP: 172.16.2.127 ; leasetime:154
Oct  2 14:37:13 mercan dhcpd: IP: 172.16.2.127 ; leasetime:297
Oct  2 14:39:37 mercan dhcpd: IP: 172.16.2.127 ; leasetime:156
Oct  2 14:42:03 mercan dhcpd: IP: 172.16.2.127 ; leasetime:154
Oct  2 14:44:28 mercan dhcpd: IP: 172.16.2.127 ; leasetime:155
Oct  2 14:46:53 mercan dhcpd: IP: 172.16.2.127 ; leasetime:155
Oct  2 14:49:18 mercan dhcpd: IP: 172.16.2.127 ; leasetime:155
Oct  2 14:49:54 mercan dhcpd: IP: 172.16.2.127 ; leasetime:264
Oct  2 14:50:47 mercan dhcpd: IP: 172.16.2.127 ; leasetime:247
Oct  2 14:51:18 mercan dhcpd: IP: 172.16.2.127 ; leasetime:269

How can log the precise lease durations, would be great if anyone has any suggestions?

Thanks in advance.
Alp

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