Something

deb ftp://ftp.ro.debian.org/debian stable main non-free contrib

ns:~# apt-cache policy
Package files:
 100 /var/lib/dpkg/status
     release a=now
 500 ftp://ftp.lug.ro stable/contrib Packages
     release v=3.1r2,o=Debian,a=stable,l=Debian,c=contrib
     origin ftp.lug.ro
 500 ftp://ftp.lug.ro stable/non-free Packages
     release v=3.1r2,o=Debian,a=stable,l=Debian,c=non-free
     origin ftp.lug.ro
 500 ftp://ftp.lug.ro stable/main Packages
     release v=3.1r2,o=Debian,a=stable,l=Debian,c=main
     origin ftp.lug.ro
Pinned packages:

ns:~# apt-cache policy perl libc6
perl:
  Installed: (none)
  Candidate: 5.8.4-8sarge4
  Version table:
     5.8.4-8sarge4 0
        500 ftp://ftp.lug.ro stable/main Packages
libc6:
  Installed: 2.3.5-13
  Candidate: 2.3.5-13
  Version table:
 *** 2.3.5-13 0
        100 /var/lib/dpkg/status
     2.3.2.ds1-22sarge3 0
        500 ftp://ftp.lug.ro stable/main Packages