nixCraft Linux Sys Admin Blog

Lighttpd Control a Directory Listing With mod_dirlisting

Posted: 07 Mar 2008 10:48 PM CST

Lighttpd web server will generate a directory listing if a directory is requested and no index-file was found in that directory. mod_dirlisting is one of the modules that is loaded by default and doesn’t have to be specified on server.modules to work.

Task: Enable Directory Listings Globally

Open lighttpd configuration file:
# vi /etc/lighttpd/lighttpd.conf
Append / modify
server.dir-listing = "enable"
OR
dir-listing.activate = "enable"
Save and close the file. Restart lighttpd:
# /etc/init.d/lighttpd restart
To disable directory listing, use:
dir-listing.activate = "disable"

Enable directory listing only for a directory

You can also enable or disable listing on selected url / directory combination. For example, display directory listing only for /files/:
$HTTP["url"] =~ "^/files($|/)" { server.dir-listing = "enable" }
OR
$HTTP["url"] =~ "^/files($|/)" { dir-listing.activate = "enable" }

Further readings:

mod_dirlist

Display IP Address Allocation Table According to Subnet Mask

Posted: 07 Mar 2008 10:24 PM CST

If you need a tabular representation of relationships and source of the various variables representing a chunk from /32 to /0 subnets use iptab command. This is useful if you are allocating IPs to end users. Following information is displayed with the command:
=> CIDR notation

=> Network Mask

=> Available Networks

=> Available Hosts per network

=> Total usable hosts

$ iptab
Sample output:

+----------------------------------------------+ | addrs   bits   pref   class  mask            | +----------------------------------------------+ |     1      0    /32          255.255.255.255 | |     2      1    /31          255.255.255.254 | |     4      2    /30          255.255.255.252 | |     8      3    /29          255.255.255.248 | |    16      4    /28          255.255.255.240 | |    32      5    /27          255.255.255.224 | |    64      6    /26          255.255.255.192 | |   128      7    /25          255.255.255.128 | |   256      8    /24      1C  255.255.255.0   | |   512      9    /23      2C  255.255.254.0   | |    1K     10    /22      4C  255.255.252.0   | |    2K     11    /21      8C  255.255.248.0   | |    4K     12    /20     16C  255.255.240.0   | |    8K     13    /19     32C  255.255.224.0   | |   16K     14    /18     64C  255.255.192.0   | |   32K     15    /17    128C  255.255.128.0   | |   64K     16    /16      1B  255.255.0.0     | |  128K     17    /15      2B  255.254.0.0     | |  256K     18    /14      4B  255.252.0.0     | |  512K     19    /13      8B  255.248.0.0     | |    1M     20    /12     16B  255.240.0.0     | |    2M     21    /11     32B  255.224.0.0     | |    4M     22    /10     64B  255.192.0.0     | |    8M     23     /9    128B  255.128.0.0     | |   16M     24     /8      1A  255.0.0.0       | |   32M     25     /7      2A  254.0.0.0       | |   64M     26     /6      4A  252.0.0.0       | |  128M     27     /5      8A  248.0.0.0       | |  256M     28     /4     16A  240.0.0.0       | |  512M     29     /3     32A  224.0.0.0       | | 1024M     30     /2     64A  192.0.0.0       | | 2048M     31     /1    128A  128.0.0.0       | | 4096M     32     /0    256A  0.0.0.0         | +----------------------------------------------+

iptab is nothing but a perl script and part of perl-Net-IP package. Here is script listing (download link):

#!/usr/bin/perl  eval 'exec /usr/bin/perl  -S $0 ${1+"$@"}'     if 0; # not running under some shell  use Net::IP; use strict;  print "+----------------------------------------------+ | addrs   bits   pref   class  mask            | +----------------------------------------------+ ";  my ($ip,$size,$class,$bits,$len);  my $ip = new Net::IP('0');  for my $len (reverse (0..32)) {          $ip->set("0.0.0.0/$len");          $size = $ip->size();          if ($size >=1048576) # 1024*1024         {                 $size /= 1048576;                 $size .= 'M';         }         elsif ($size >= 1024)         {                 $size /= 1024;                 $size .= 'K';         };          $len = $ip->prefixlen();         $bits = 32 - $len;          if ($bits >= 24)         {                 $class = 2**($bits-24);                 $class.= 'A';         }         elsif ($bits >= 16)         {                 $class = 2**($bits-16);                 $class.= 'B';         }         elsif ($bits >=          {                 $class = 2**($bits-8);                 $class.= 'C';         }          printf ("| %5s %6s %6s %7s  %-15s |\n",                 $size,$bits,'/'.$len,$class,$ip->mask());  };  print "+----------------------------------------------+\n";

Linux sudo Configuration

Posted: 08 Mar 2008 01:09 AM CST

Q. Can you tell me how to configure sudo to provide access to end users? How do I allow to run programs with the security privileges of another user using sudo?

Answer to "Linux sudo Configuration"