Openwrt isc-dhcpd-4.2.4

Every time the dhcp service starts, it listens not only on 0.0.0.0:67 but also on 0.0.0.0:PORT where PORT is a random number.

Anyone knows where this behaviour comes from?

root@OpenWrt:/# netstat -ntapue
Active Internet connections (servers and established)
Proto Recv-Q Send-Q Local Address           Foreign Address         State       PID/Program name    
tcp        0      0 10.0.16.1:22            0.0.0.0:*               LISTEN      898/sshd
netstat: /proc/net/tcp6: No such file or directory
udp        0      0 10.0.16.1:514           0.0.0.0:*                           922/syslog-ng
udp        0      0 0.0.0.0:60738           0.0.0.0:*                           1290/dhcpd
udp        0      0 0.0.0.0:67              0.0.0.0:*                           1290/dhcpd
udp        0      0 10.0.16.1:69            0.0.0.0:*                           974/tftpd-hpa
netstat: /proc/net/udp6: No such file or directory

My config is:

# dhcpd.conf

ddns-updates off;

authoritative;

# don't let clients modify their own A records
ignore client-updates;

default-lease-time 3600;
max-lease-time 86400;

option domain-name "lan";

option domain-name-servers 212.24.188.130, 212.24.188.131;

subnet 10.0.16.0 netmask 255.255.255.0 {
        host marvin
        { hardware ethernet 48:5D:11:2F:22:31;
        fixed-address 10.0.16.202; }
      range 10.0.16.207 10.0.16.209;
      option subnet-mask 255.255.255.0;
      option broadcast-address 10.0.16.255;
      option routers 10.0.16.1;
      deny unknown-clients;

      next-server 10.0.16.1;
      filename "pxelinux.0";
}