Free monitoring software for linux

Skipole Network Monitor project is a simple network monitor with built in web server.

It allows the user to input host IP addresses, it then pings these hosts every five minutes and displays their status via a built-in web server, on port 8000.

So calling http://your_pc_address:8000 will display pages showing green, yellow or red host or group symbols.

Each host is pinged four times every five minutes, and symbols are displayed as:

green : if three or four pings are successfull
yellow : if only one or two are successfull
red : if all four fail

As well as hosts, group symbols are displayed, and can be opened to show hosts, or sub-groups nested within. The operator can create groups, and sub-groups via the gui.

Devel::Monitor is a Perl module that can monitor your variables/objects for memory leaks.

You have memory leaks, and you want to remove it... You can use this tool to help you find which variables/objects that are not destroyed when they should be, and thereafter, you can visualise exactly where is the circular reference for some specific variables/objects.

WHAT IT CANT DO

Even if your modules are memory leak free, it doesnt mean that external modules that you are using dont have it. So, before running your application on mod_perl, you should be sure that EVERY modules are ok. (In particular those perl extensions calling C++ code)

SYNOPSIS

use Devel::Monitor qw(:all);

#-----------------------------------------------------------------------------
# Monitor scalars, arrays, hashes, references, constants
#-----------------------------------------------------------------------------
my ($a,$b) = (Foo::Bar->new(), Foo::Bar->new());
my ($c, @d, %e);
use constant F => [1,2];
monitor(name for a => $a,
name for b => $b,
name for c => $c,
name for d => @d,
name for e => %e,
name for F => &F); #NOTE : Dont add parentheses to the end of the constant (&F())

#-----------------------------------------------------------------------------
# Print circular references
#-----------------------------------------------------------------------------
# NOTE : You cannot use print_circular_ref on a monitored/tied variable
# (See "We cannot use tied objects references because it reuse memory space" doc)
print_circular_ref($a);
print_circular_ref($b);
print_circular_ref($c);
print_circular_ref(@d);
print_circular_ref(%e);
print_circular_ref(&F); #NOTE : Dont add parentheses to the end of the constant (&F())

USAGE : monitor

Example with a circular reference
+----------------------+
| Code |
+----------------------+
{
my @a;
monitor(a => @a);
$a[0] = @a; #Add a circular reference
print STDERR "Leaving scopen";
}
print STDERR "Scope leftn";

+----------------------+
| Output |
+----------------------+
MONITOR ARRAY a
Leaving scope
Scope left
DESTROY ARRAY a

+----------------------+
| Meaning |
+----------------------+
The line "DESTROY ARRAY a" should be between scope prints.
@a were deleted on program exit.

Example without a circular reference

+----------------------+
| Code |
+----------------------+
{
my @a;
monitor(a => @a);
print STDERR "Leaving scopen";
}
print STDERR "Scope leftn";

+----------------------+
| Output |
+----------------------+
MONITOR ARRAY a
Leaving scope
DESTROY ARRAY a
Scope left

+----------------------+
| Meaning |
+----------------------+
Everything is ok

Now that you know there is a circular reference, you can track it down using the print_circular_ref method

tk_docapp project is a small GUI for mounting devices and ACPI energy monitoring under NetBSD.

User of other *nix operating systems can only use the mount option.

GroundWork Monitor Open Source is a complete availability monitoring solution that ensures IT infrastructure uptime while identifying issues before they become real problems.

Unifies best-of-breed open source tools - Nagios*, Nmap, SNMP TT, PHP, Apache, MySQL and more — through PHP/AJAX-based components and an integrated user interface to deliver the extensible functionality you require.

bandwidth monitor is a small application which polls /proc/net/dev for the byte counts for a given network device , and calculates the RX and TX bandwidths. Originally a shell script, then a Perl script, now rewritten in C so that it can easily be used on embedded devices like the Linksys WRT54G as well as.

This program started as a shell script that I ran on my home-brew firewall wireless router (Linux, of course, on a 486/66) to keep track of my incoming and outgoing bandwidth. This let me know that I was getting the bandwidth that I paid for, and it also helped me keep an eye on the throttling of bulk traffic so that I didnt choke out my interactive sessions. Of course, that was before I had QOS.

The program is probably tied to Linux, since it grabs the byte counts for the requested interface right from /proc/net/dev. It could pretty easily be modified to grab the same information from the output of /sbin/ifconfig, but that would waste resources to spawn a new process to parse the /proc/net/dev file and regurgitate it to us. Also, I havent bothered to look at how uniform the output of the byte counts from /sbin/ifconfig is on other operating systems.

As a side note, the C version also uses nanosleep() and gettimeofday() to get more accurate polling intervals and track the overall time (since sleep(), usleep(), nanosleep(), et. al. only guaruntee to wait at least as long as you request, but do not guaruntee that it wont be possibly much longer...) So, if you were interested in porting it, youd have to make sure that nanosleep() and gettimeofday() were also available, or lose the resolution of the time used in bandwidth calculations.

BUILDING

$ gcc -O3 -o bandwidth_monitor bandwidth_monitor.c