daemon.log is growing, only if connected to the Internet

My Notebook is connected to the Internet by a Router.
There is also a DHCP server included.
The file /var/log/daemon.log contains the following lines (which repeat oneself).

Sep 1 18:32:39 laptop pumpd[169]: bresp: vendor: 0x63 0x82 0x53 0x63
Sep 1 18:32:39 laptop pumpd[169]: bresp: vendor: 53 1 0x05
Sep 1 18:32:39 laptop pumpd[169]: bresp: vendor: 54 4 0xc0 0xa8 0x01 0x01
Sep 1 18:32:39 laptop pumpd[169]: bresp: vendor: 51 4 0xff 0xff 0xff 0xc4
Sep 1 18:32:39 laptop pumpd[169]: bresp: vendor: 58 4 0xff 0xff 0xff 0xe2
Sep 1 18:32:39 laptop pumpd[169]: bresp: vendor: 59 4 0xff 0xff 0xff 0xcc
Sep 1 18:32:39 laptop pumpd[169]: bresp: vendor: 1 4 0xff 0xff 0xff 0x00
Sep 1 18:32:39 laptop pumpd[169]: bresp: vendor: 3 4 0xc0 0xa8 0x01 0x01
Sep 1 18:32:39 laptop pumpd[169]: bresp: vendor: 6 4 0xc0 0xa8 0x01 0x01
Sep 1 18:32:39 laptop pumpd[169]: bresp: vendor: 15 1 0x00
Sep 1 18:32:39 laptop pumpd[169]: bresp: vendor: 0xff
Sep 1 18:32:39 laptop pumpd[169]: renewed lease for interface eth0
Sep 1 18:32:39 laptop pumpd[169]: breq: opcode: 1
Sep 1 18:32:39 laptop pumpd[169]: breq: hw: 1
Sep 1 18:32:39 laptop pumpd[169]: breq: hwlength: 6
Sep 1 18:32:39 laptop pumpd[169]: breq: hopcount: 0
Sep 1 18:32:39 laptop pumpd[169]: breq: xid: 0xfca2b5d7
Sep 1 18:32:39 laptop pumpd[169]: breq: secs: 0
Sep 1 18:32:39 laptop pumpd[169]: breq: flags: 0x0000
Sep 1 18:32:39 laptop pumpd[169]: breq: ciaddr: 192.168.1.6
Sep 1 18:32:39 laptop pumpd[169]: breq: yiaddr: 0.0.0.0
Sep 1 18:32:39 laptop pumpd[169]: breq: server_ip: 0.0.0.0
Sep 1 18:32:39 laptop pumpd[169]: breq: bootp_gw_ip: 0.0.0.0
Sep 1 18:32:39 laptop pumpd[169]: breq: hwaddr:
Sep 1 18:32:39 laptop pumpd[169]: breq: servername:
Sep 1 18:32:39 laptop pumpd[169]: breq: bootfile:
Sep 1 18:32:39 laptop pumpd[169]: breq: vendor: 0x63 0x82 0x53 0x63
Sep 1 18:32:39 laptop pumpd[169]: breq: vendor: 53 1 0x03
Sep 1 18:32:39 laptop pumpd[169]: breq: vendor: 12 7 0x6c 0x61 0x70 0x74
Sep 1 18:32:39 laptop pumpd[169]: breq: vendor: ++++++ 0x6f 0x70 0x00
Sep 1 18:32:39 laptop pumpd[169]: breq: vendor: 51 4 0x00 0x00 0xa8 0xc0
Sep 1 18:32:39 laptop pumpd[169]: breq: vendor: 0xff
Sep 1 18:32:39 laptop pumpd[169]: bresp: opcode: 2
Sep 1 18:32:39 laptop pumpd[169]: bresp: hw: 1
Sep 1 18:32:39 laptop pumpd[169]: bresp: hwlength: 6
Sep 1 18:32:39 laptop pumpd[169]: bresp: hopcount: 0
Sep 1 18:32:39 laptop pumpd[169]: bresp: xid: 0xfca2b5d7
Sep 1 18:32:39 laptop pumpd[169]: bresp: secs: 0
Sep 1 18:32:39 laptop pumpd[169]: bresp: flags: 0x0000
Sep 1 18:32:39 laptop pumpd[169]: bresp: ciaddr: 192.168.1.6
Sep 1 18:32:39 laptop pumpd[169]: bresp: yiaddr: 192.168.1.6
Sep 1 18:32:39 laptop pumpd[169]: bresp: server_ip: 192.168.1.1
Sep 1 18:32:39 laptop pumpd[169]: bresp: bootp_gw_ip: 0.0.0.0
Sep 1 18:32:39 laptop pumpd[169]: bresp: hwaddr:
Sep 1 18:32:39 laptop pumpd[169]: bresp: servername:
Sep 1 18:32:39 laptop pumpd[169]: bresp: bootfile:

Sep 1 18:32:39 laptop pumpd[169]: bresp: vendor: 0x63 0x82 0x53 0x63

The file daemon.log is getting too big (4 GB).
Can anybody help me ?