2.3 Deciding which mirror is the best to include in the sources.list file: netselect, netselect-apt

A very frequent doubt, mainly among the newest users is: "which Debian mirror to include in sources.list?". There are many ways to decide which mirror. The experts probably have a script that measures the ping time through the several mirrors. But there's a program that does this for us: netselect.

To install netselect, as usual:

     # apt-get install netselect

Executing it without parameters shows the help. Executing it with a space-separated list of hosts (mirrors), it will return a score and one of the hosts. This score takes in consideration the estimated ping time and the hops (hosts by which a network query will pass by to reach the destination) number and is inversely proportional to the estimated download speed (so, the lower, the better). The returned host is the one that had the lowest score (the full list of scores can be seen adding the -vv option). See this example:

     # netselect ftp.debian.org http.us.debian.org ftp.at.debian.org download.unesp.br ftp.debian.org.br
       365 ftp.debian.org.br
     #

This means that, from the mirrors included as parameters to netselect, ftp.debian.org.br was the best, with an score of 365. (Attention!! As it was done on my computer and the network topography is extremely different depending on the contact point, this value is not necessarily the right speed in other computers).

Now, just put the fastest mirror found by netselect in the /etc/apt/sources.list file (see The /etc/apt/sources.list file, Section 2.1) and follow the tips in Managing packages, Chapter 3.

Note: the list of mirrors may always be found in the file https://www.debian.org/mirror/mirrors_full.

Beginning with the 0.3.ds1 version, the netselect source package includes the netselect-apt binary package, which makes the process above automatic. Just enter the distribution tree as parameter (the default is stable) and the sources.list file will be generated with the best main and non-US mirrors and will be saved under the current directory. The following example generates a sources.list of the stable distribution:

     # ls sources.list
     ls: sources.list: File or directory not found
     # netselect-apt stable
     (...)
     # ls -l sources.list
     sources.list
     #

Remember: the sources.list file is generated under the current directory, and must be moved to the /etc/apt directory.

Then, follow the tips in Managing packages, Chapter 3.