After I replaced all the contents of /etc/network/interfaces with the above lines, the result is:
ertugrul eva:~$ sudo ifup eth1
Password:
Internet Systems Consortium DHCP Client
V3.0.3
Copyright 2004-2005 Internet Systems Consortium.
All rights reserved.
For info, please visit
http://www.isc.org/products/DHCPListening on LPF/eth1/00:13:02:46:28:1e
Sending on LPF/eth1/00:13:02:46:28:1e
Sending on Socket/fallback
DHCPDISCOVER on eth1 to
255.255.255.255 port 67 interval 6
DHCPDISCOVER on eth1 to
255.255.255.255 port 67 interval 8
DHCPDISCOVER on eth1 to
255.255.255.255 port 67 interval 18
DHCPDISCOVER on eth1 to
255.255.255.255 port 67 interval 19
DHCPDISCOVER on eth1 to
255.255.255.255 port 67 interval 10
No DHCPOFFERS received.
No working leases in persistent database - sleeping.
ertugrul eva:~$ sudo ifup eth1
ifup: interface eth1 already configured