- SAM - Virus

Is your computer infected by virus named -SAM - ? Are you not able to surf your favorite websites like orkut or proxy sites ? Irritated due to activities of that virus? Here is the solution !!


One thing I want make clear is that, This is not a “Computer virus”. (You may check the definition of that word on the net) Then what exactly is it ?

It is actually a computer program designed to block the website not expected in colleges, companies or any other official places. This -SAM- program will only block pornographic sites, harmful sites and sites like orkut, my space n so on.

What can be assured is it will not harm your computer in any way, also its not having any kind of destructive purpose. Instead if -SAM- is running, rest of the viruses cant exist in the same computer, yes this is one of the best features of -SAM- program.

-SAM- was actually a module of our project “System Maintenance Suite” - one of the top 8 softwares awarded in India in IIT TechFest !

-SAM- was spread by mistake while experimenting on college PCs, want to say that it was not spread desperately. Still if you don’t like that you may run the removal of -SAM- provided above.

S.M.A.R.T. Server

Following is the abstract of my B.E. final year project :


1.1. Preface

We all are living in the computer era where almost everything is automated and computer controlled. This SMART Server also aims to have complete network management. The system administrator or analyst of the company or organization would be pleased if he is given something that will automatically keep track of all inventories present in the campus, something that manages the clients and the web traffic, something that helps him to solve the problems remotely. Now the wait is over. Yes, that abstract “something” is realized as SMART Server. Its acronym for Self Monitoring, Analysis and Reporting Technology based Server. 

In today’s world, all the things mentioned above are of extreme importance. The organization can see the quick snapshot of organization’s IT structure and assure that everything is alright. If not, then it can take the appropriate actions. The real-time reports can surely help the system controller to work more efficiently and fast. The implementation is totally based on “open source projects” like Apache, PHP, etc. So, in turn, the SMART Server inherits the powerful features, for instance, fast and flexible client-server interaction, security, platform independence, etc.



1.2. Statement of Problem

Consider an organization where there are many computers and other related inventory. Now it is quite necessary for the system administrator or analyst to:

  1. Know all devices connected to IT network.
  2. Know which software or hardware component is installed on a computer.
  3. Have ability to deploy software or configuration scripts on computers.
  4. Keep something between users and the Internet to handle web requests.
  5. Provide protection for users and use a web cache to make browsing faster.
  6. Have total traffic management and content filtering.
  7. Be able to solve software related problems remotely.



1.3. Objectives of Project 

Considering the problem statement, moving towards the solution, our project has following objectives.

SMART Server - 

  • Should have a proxy server that allows Total Access Control, Total Content Security, allows easy scalability in really large environments and most importantly, easy to implement, manage and tweak, as per every-day needs. 
  • Should determine what the components of your network are, how they are configured and when they change. 
  • System administrator should be able to resolve the problems remotely. 
  • It should be platform independent that is works perfectly under Windows, Linux or any other system architecture. 
  • Should have web based interface so that it must be accessible from any browsers. 

Thus, SMART Server, an automated network management suite is exactly “What you want is what you get.”


1.4. Scope of the Project 

Keeping track of your machines is an essential enterprise task that facilitates hardware and software management, license compliance, regulatory compliance, and security. Indeed, a successful asset management solution can save companies time, money, and lots of management headaches. 

Such a solution is essential for tracking all of your hardware and software assets. It can tell you where they're located, how they're configured, and when any changes are made to them. An asset management solution can provide an audit of manufacturer model and serial number, processor configuration, and even memory installed with free slots. An asset management solution can audit this information quickly and thus help an organization.

Another major job of IT manager is to let the clients use the network bandwidth efficiently. This can be achieved using the caching technique. A proxy server helps in monitoring, controlling the network traffic in extra-ordinary way. Use of Virtual Computing technology to solve the client problems is a good idea, which allows one to control the remote computer machine virtually from any location in the world. 


1.5. Organization of the Project

Its acronym for Self Monitoring, Analysis and Reporting Technology based Server. As its name suggests, it provides self monitoring, analysing and reporting of the related data. For this purpose, SMART Server is organized of the following basic modules – 

· SMART Proxy

· SMART AudIT

· SMART Virtual Computing


SMART Proxy:

It is a proxy server is a server which services the requests of its clients by forwarding requests to other servers. A client connects to the proxy server, requesting some service, such as a file, connection, web page, or other resource, available from a different server. 

A SMART Proxy can reply to service requests without contacting the specified server, by retrieving content saved from a previous request, made by the same client or even other clients. This is called caching. Caching proxies keep local copies of frequently requested resources, allowing large organizations to significantly reduce their upstream bandwidth usage and cost, while significantly increasing performance. Proxy programs provide a means to deny access to certain URLs in a blacklist, thus providing content filtering. 

SMART AudIT:

The auditing module intelligently “discovers” software installed across the computer network, and collects software file information such as title, product ID, size, date, path, and version. It also compares software inventory data with purchasing information to reveal license deficits and ensure that organizations remain compliant with their licensing agreements.


SMART Virtual Computing:

SMART Virtual Computing is a remote control software package derived from the popular VNC software. With SMART Virtual Computing, you can see the desktop of a remote machine and control it with your local mouse and keyboard, just like you would do it sitting in the front of that computer.


System Maintenance Suite

This is the project that I show cased at IIT Mumbai while pursuing my engineering from SSGMCE and was among the top 8 projects throughout India. Here is an abstract :


1. Idea of project:

Every computer user thinks that his/her computer should work smoothly without any problem, may be caused by the viruses, faulty application softwares, registry errors, etc. One has to use various applications to defeat each problem respectively. For instance, registry cleaner for cleaning registry only. Still it’s not guaranteed that the error will be resolved. For example, an antivirus may remove the viruses but not cure the damages created by the viruses. The idea behind creating this software is to aid computer user to enjoy problem free computer. As maintenance is a part of any system, an all in one reliable solution may prove better for dealing with the various situations.

2. How does this Software work? 

As stated earlier, problems and errors in the computers are mainly due to the viruses, Trojans, registry errors, application faults, etc. If we analyze all the problems, it can be seen that actually windows registry gets infected. Now windows registry is the place where all the configuration information is stored. Windows every now and then refers to this registry for its operation.

As soon as any value in this registry is disturbed, windows may give unwanted results accordingly. Same is the case with the application faults, missing or changing of any file throws an error to user. All this may lead to slowing down the speed of computer. Thus if we could prevent files or the registry values from being changed, we can keep our system safe and sound. And that’s the principle of this software. We are actually resetting the original configuration of computer to get rid of the problems. That is our AHK based interface allows us to use amazing power of registry to completely conquer the system. Here it doesn’t require remembering all the paths to registry values or monitoring of any file changed or missed. All these facilities are provided in excellent Graphical User Interface.
  • H/W required: Any PC (P4)
  • S/W required: Compatible OS: Windows XP with Administrative privileges.
  • Programming Languages Used: Shell Scripting, AHK scripts, VB.

In this suite, AHK scripting, which is most popular script used to create applications, is used for performing background executions such as editing registry or system monitoring. And rest of the Interface is provided by VB and Shell scripting, visible to computer user.

3. Problem for which the project is worked out as a solution:

The problem can be seen as a set of all the unwanted errors in computer system which interrupts the normal processing of system. It also involves problem of slowing down the speed of computer even though it’s having good configuration. Thus the problem is to convert a dull system to the level of performance where it is expected to be.

In order to make the system ability to noticeable state, all the necessary tweaks must be accomplished. It incorporates:

Ø Registry correction,
Ø Increasing speed of computer,
Ø Implementing security matters,
Ø Removing of most irritating viruses,
Ø Correcting problems caused by them,
Ø Increasing browsing speed,
Ø Instant access to frequently used utilities,
Ø System optimizing and one stop cleaning
Ø Blocking of Obscene websites permanently, etc

4. Marketability of the project and its commercial applications:

As no software product is available in the market which incorporates all the features stated earlier, this System Maintenance Suite has a wide scope. It’s actually a market requirement to have such multipurpose product which does basic functions.

After installing a fresh XP on all the PCs of any organization, just like other essential drivers and programs, this is “must have” software for complete system maintenance.


5. Other aspect of the project:

With a higher level of performance, one more important pros of this product is its extensibility facility. Yes, any time new definitions of the viruses or the tweaks can be added or deleted according to our need. Thus requirements of updating itself just like other good products are also fulfilled, which makes the software completely flexible.

20 Linux System Monitoring Tools Every SysAdmin Should Know


Need to monitor Linux server performance? Try these built-in command and a few add-on tools. Most Linux distributions are equipped with tons of monitoring. These tools provide metrics which can be used to get information about system activities. You can use these tools to find the possible causes of a performance problem. The commands discussed below are some of the most basic commands when it comes to system analysis and debugging server issues such as:

  1. Finding out bottlenecks.
  2. Disk (storage) bottlenecks.
  3. CPU and memory bottlenecks.
  4. Network bottlenecks.



#1: top - Process Activity Command


The top program provides a dynamic real-time view of a running system i.e. actual process activity. By default, it displays the most CPU-intensive tasks running on the server and updates the list every five seconds.


Fig.01: Linux top command

Fig.01: Linux top command

Commonly Used Hot Keys


The top command provides several useful hot keys:

Hot Key Usage
t Displays summary information off and on.
m Displays memory information off and on.
A Sorts the display by top consumers of various system resources. Useful for quick identification of performance-hungry tasks on a system.
f Enters an interactive configuration screen for top. Helpful for setting up top for a specific task.
o Enables you to interactively select the ordering within top.
r Issues renice command.
k Issues kill command.
z Turn on or off color/mono






#2: vmstat - System Activity, Hardware and System Information


The command vmstat reports information about processes, memory, paging, block IO, traps, and cpu activity.

# vmstat 3

 
Sample Outputs:

 
 
procs -----------memory---------- ---swap-- -----io---- --system-- -----cpu------ 
 
 r  b   swpd   free   buff  cache   si   so    bi    bo   in   cs us sy id wa st
 0  0      0 2540988 522188 5130400    0    0     2    32    4    2  4  1 96  0  0
 1  0      0 2540988 522188 5130400    0    0     0   720 1199  665  1  0 99  0  0
 0  0      0 2540956 522188 5130400    0    0     0     0 1151 1569  4  1 95  0  0
 0  0      0 2540956 522188 5130500    0    0     0     6 1117  439  1  0 99  0  0
 0  0      0 2540940 522188 5130512    0    0     0   536 1189  932  1  0 98  0  0
 0  0      0 2538444 522188 5130588    0    0     0     0 1187 1417  4  1 96  0  0
 0  0      0 2490060 522188 5130640    0    0     0    18 1253 1123  5  1 94  0  0

Display Memory Utilization Slabinfo


# vmstat -m

Get Information About Active / Inactive Memory Pages


# vmstat -a




#3: w - Find Out Who Is Logged on And What They Are Doing


w command displays information about the users currently on the machine, and their processes.
# w username
# w Snehal
 
Sample Outputs:

 
  17:58:47 up 5 days, 20:28,  2 users,  load average: 0.36, 0.26, 0.24 
 
USER     TTY      FROM              LOGIN@   IDLE   JCPU   PCPU WHAT 
root     pts/0    10.1.3.145       14:55    5.00s  0.04s  0.02s vim /etc/resolv.conf
root     pts/1    10.1.3.145       17:43    0.00s  0.03s  0.00s w
 
 


#4: uptime - Tell How Long The System Has Been Running


The uptime command can be used to see how long the server has been running. The current time, how long the system has been running, how many users are currently logged on, and the system load averages for the past 1, 5, and 15 minutes.
# uptime

Output:

 18:02:41 up 41 days, 23:42,  1 user,  load average: 0.00, 0.00, 0.00

1 can be considered as optimal load value. The load can change from system to system. For a single CPU system 1 - 3 and SMP systems 6-10 load value might be acceptable.


#5: ps - Displays The Processes


ps command will report a snapshot of the current processes. To select all processes use the -A or -e option:
# ps -A

Sample Outputs:

  PID TTY          TIME CMD
    1 ?        00:00:02 init
    2 ?        00:00:02 migration/0
    3 ?        00:00:01 ksoftirqd/0
    4 ?        00:00:00 watchdog/0
    5 ?        00:00:00 migration/1
    6 ?        00:00:15 ksoftirqd/1
....
.....
 4881 ?        00:53:28 java
 4885 tty1     00:00:00 mingetty
 4886 tty2     00:00:00 mingetty
 4887 tty3     00:00:00 mingetty
 4888 tty4     00:00:00 mingetty
 4891 tty5     00:00:00 mingetty
 4892 tty6     00:00:00 mingetty
 4893 ttyS1    00:00:00 agetty
12853 ?        00:00:00 cifsoplockd
12854 ?        00:00:00 cifsdnotifyd
14231 ?        00:10:34 lighttpd
14232 ?        00:00:00 php-cgi
54981 pts/0    00:00:00 vim
55465 ?        00:00:00 php-cgi
55546 ?        00:00:00 bind9-snmp-stat
55704 pts/1    00:00:00 ps

ps is just like top but provides more information.

Show Long Format Output


# ps -Al
To turn on extra full mode (it will show command line arguments passed to process):
# ps -AlF

To See Threads ( LWP and NLWP)


# ps -AlFH

To See Threads After Processes


# ps -AlLm

Print All Process On The Server


# ps ax
# ps axu

Print A Process Tree


# ps -ejH
# ps axjf
# pstree

Print Security Information


# ps -eo euser,ruser,suser,fuser,f,comm,label
# ps axZ
# ps -eM

See Every Process Running As User Vivek


# ps -U vivek -u vivek u

Set Output In a User-Defined Format


# ps -eo pid,tid,class,rtprio,ni,pri,psr,pcpu,stat,wchan:14,comm
# ps axo stat,euid,ruid,tty,tpgid,sess,pgrp,ppid,pid,pcpu,comm
# ps -eopid,tt,user,fname,tmout,f,wchan

Display Only The Process IDs of Lighttpd


# ps -C lighttpd -o pid=
OR
# pgrep lighttpd

OR
# pgrep -u vivek php-cgi

Display The Name of PID 55977


# ps -p 55977 -o comm=

Find Out The Top 10 Memory Consuming Process


# ps -auxf | sort -nr -k 4 | head -10

Find Out top 10 CPU Consuming Process


# ps -auxf | sort -nr -k 3 | head -10


#6: free - Memory Usage


The command free displays the total amount of free and used physical and swap memory in the system, as well as the buffers used by the kernel.
# free

Sample Output:

            total       used       free     shared    buffers     cached
Mem:      12302896    9739664    2563232          0     523124    5154740
-/+ buffers/cache:    4061800    8241096
Swap:      1052248          0    1052248





#7: iostat - Average CPU Load, Disk Activity


The command iostat report Central Processing Unit (CPU) statistics and input/output statistics for devices, partitions and network filesystems (NFS).
# iostat

Sample Outputs:

Linux 2.6.18-128.1.14.el5 (www03.nixcraft.in)  06/26/2009

avg-cpu:  %user   %nice %system %iowait  %steal   %idle
           3.50    0.09    0.51    0.03    0.00   95.86

Device:            tps   Blk_read/s   Blk_wrtn/s   Blk_read   Blk_wrtn
sda              22.04        31.88       512.03   16193351  260102868
sda1              0.00         0.00         0.00       2166        180
sda2             22.04        31.87       512.03   16189010  260102688
sda3              0.00         0.00         0.00       1615          0
 
 


#8: sar - Collect and Report System Activity


The sar command is used to collect, report, and save system activity information. To see network counter, enter:
# sar -n DEV | more

To display the network counters from the 24th:
# sar -n DEV -f /var/log/sa/sa24 | more

You can also display real time usage using sar:
# sar 4 5

Sample Outputs:

Linux 2.6.18-128.1.14.el5 (www03.nixcraft.in)   06/26/2009

06:45:12 PM       CPU     %user     %nice   %system   %iowait    %steal     %idle
06:45:16 PM       all      2.00      0.00      0.22      0.00      0.00     97.78
06:45:20 PM       all      2.07      0.00      0.38      0.03      0.00     97.52
06:45:24 PM       all      0.94      0.00      0.28      0.00      0.00     98.78
06:45:28 PM       all      1.56      0.00      0.22      0.00      0.00     98.22
06:45:32 PM       all      3.53      0.00      0.25      0.03      0.00     96.19
Average:          all      2.02      0.00      0.27      0.01      0.00     97.70
 
 


#9: mpstat - Multiprocessor Usage


The mpstat command displays activities for each available processor, processor 0 being the first one. mpstat -P ALL to display average CPU utilization per processor:
# mpstat -P ALL

Sample Output:

Linux 2.6.18-128.1.14.el5 (www03.nixcraft.in)   06/26/2009

06:48:11 PM  CPU   %user   %nice    %sys %iowait    %irq   %soft  %steal   %idle    intr/s
06:48:11 PM  all    3.50    0.09    0.34    0.03    0.01    0.17    0.00   95.86   1218.04
06:48:11 PM    0    3.44    0.08    0.31    0.02    0.00    0.12    0.00   96.04   1000.31
06:48:11 PM    1    3.10    0.08    0.32    0.09    0.02    0.11    0.00   96.28     34.93
06:48:11 PM    2    4.16    0.11    0.36    0.02    0.00    0.11    0.00   95.25      0.00
06:48:11 PM    3    3.77    0.11    0.38    0.03    0.01    0.24    0.00   95.46     44.80
06:48:11 PM    4    2.96    0.07    0.29    0.04    0.02    0.10    0.00   96.52     25.91
06:48:11 PM    5    3.26    0.08    0.28    0.03    0.01    0.10    0.00   96.23     14.98
06:48:11 PM    6    4.00    0.10    0.34    0.01    0.00    0.13    0.00   95.42      3.75
06:48:11 PM    7    3.30    0.11    0.39    0.03    0.01    0.46    0.00   95.69     76.89
 



#10: pmap - Process Memory Usage


The command pmap report memory map of a process. Use this command to find out causes of memory bottlenecks.
# pmap -d PID

To display process memory information for pid # 47394, enter:
# pmap -d 47394

Sample Outputs:

47394:   /usr/bin/php-cgi
Address           Kbytes Mode  Offset           Device    Mapping
0000000000400000    2584 r-x-- 0000000000000000 008:00002 php-cgi
0000000000886000     140 rw--- 0000000000286000 008:00002 php-cgi
00000000008a9000      52 rw--- 00000000008a9000 000:00000   [ anon ]
0000000000aa8000      76 rw--- 00000000002a8000 008:00002 php-cgi
000000000f678000    1980 rw--- 000000000f678000 000:00000   [ anon ]
000000314a600000     112 r-x-- 0000000000000000 008:00002 ld-2.5.so
000000314a81b000       4 r---- 000000000001b000 008:00002 ld-2.5.so
000000314a81c000       4 rw--- 000000000001c000 008:00002 ld-2.5.so
000000314aa00000    1328 r-x-- 0000000000000000 008:00002 libc-2.5.so
000000314ab4c000    2048 ----- 000000000014c000 008:00002 libc-2.5.so
.....
......
..
00002af8d48fd000       4 rw--- 0000000000006000 008:00002 xsl.so
00002af8d490c000      40 r-x-- 0000000000000000 008:00002 libnss_files-2.5.so
00002af8d4916000    2044 ----- 000000000000a000 008:00002 libnss_files-2.5.so
00002af8d4b15000       4 r---- 0000000000009000 008:00002 libnss_files-2.5.so
00002af8d4b16000       4 rw--- 000000000000a000 008:00002 libnss_files-2.5.so
00002af8d4b17000  768000 rw-s- 0000000000000000 000:00009 zero (deleted)
00007fffc95fe000      84 rw--- 00007ffffffea000 000:00000   [ stack ]
ffffffffff600000    8192 ----- 0000000000000000 000:00000   [ anon ]
mapped: 933712K    writeable/private: 4304K    shared: 768000K

The last line is very important:

  • mapped: 933712K total amount of memory mapped to files
  • writeable/private: 4304K the amount of private address space
  • shared: 768000K the amount of address space this process is sharing with others
  •  


#11 and #12: netstat and ss - Network Statistics


The command netstat displays network connections, routing tables, interface statistics, masquerade connections, and multicast memberships. ss command is used to dump socket statistics. It allows showing information similar to netstat. 

#13: iptraf - Real-time Network Statistics


The iptraf command is interactive colorful IP LAN monitor. It is an ncurses-based IP LAN monitor that generates various network statistics including TCP info, UDP counts, ICMP and OSPF information, Ethernet load info, node stats, IP checksum errors, and others. It can provide the following info in easy to read format:

  • Network traffic statistics by TCP connection
  • IP traffic statistics by network interface
  • Network traffic statistics by protocol
  • Network traffic statistics by TCP/UDP port and by packet size
  • Network traffic statistics by Layer2 address

Fig.02: General interface statistics: IP traffic statistics by network interface

Fig.02: General interface statistics: IP traffic statistics by network interface 


Fig.03 Network traffic statistics by TCP connection

Fig.03 Network traffic statistics by TCP connection


 

#14: tcpdump - Detailed Network Traffic Analysis



The tcpdump is simple command that dump traffic on a network. However, you need good understanding of TCP/IP protocol to utilize this tool. For.e.g to display traffic info about DNS, enter:
# tcpdump -i eth1 'udp port 53'

To display all IPv4 HTTP packets to and from port 80, i.e. print only packets that contain data, not, for example, SYN and FIN packets and ACK-only packets, enter:
# tcpdump 'tcp port 80 and (((ip[2:2] - ((ip[0]&0xf)<<2)) - ((tcp[12]&0xf0)>>2)) != 0)'

To display all FTP session to 202.54.1.5, enter:
# tcpdump -i eth1 'dst 202.54.1.5 and (port 21 or 20'

To display all HTTP session to 192.168.1.5:
# tcpdump -ni eth0 'dst 192.168.1.5 and tcp and port http'

Use wireshark to view detailed information about files, enter:
# tcpdump -n -i eth1 -s 0 -w output.txt src or dst port 80


#15: strace - System Calls


Trace system calls and signals. This is useful for debugging webserver and other server problems. See how to use to trace the process and see What it is doing.


#16: /Proc file system - Various Kernel Statistics


/proc file system provides detailed information about various hardware devices and other Linux kernel information. See Linux kernel /proc documentations for further details. Common /proc examples:
# cat /proc/cpuinfo
# cat /proc/meminfo
# cat /proc/zoneinfo
# cat /proc/mounts


 

#17: Nagios - Server And Network Monitoring


Nagios is a popular open source computer system and network monitoring application software. You can easily monitor all your hosts, network equipment and services. It can send alert when things go wrong and again when they get better. FAN is "Fully Automated Nagios". FAN goals are to provide a Nagios installation including most tools provided by the Nagios Community. FAN provides a CDRom image in the standard ISO format, making it easy to easilly install a Nagios server. Added to this, a wide bunch of tools are including to the distribution, in order to improve the user experience around Nagios.



#18: Cacti - Web-based Monitoring Tool


Cacti is a complete network graphing solution designed to harness the power of RRDTool's data storage and graphing functionality. Cacti provides a fast poller, advanced graph templating, multiple data acquisition methods, and user management features out of the box. All of this is wrapped in an intuitive, easy to use interface that makes sense for LAN-sized installations up to complex networks with hundreds of devices. It can provide data about network, CPU, memory, logged in users, Apache, DNS servers and much more. See how to install and configure Cacti network graphing tool under CentOS / RHEL.


#19: KDE System Guard - Real-time Systems Reporting and Graphing


KSysguard is a network enabled task and system monitor application for KDE desktop. This tool can be run over ssh session. It provides lots of features such as a client/server architecture that enables monitoring of local and remote hosts. The graphical front end uses so-called sensors to retrieve the information it displays. A sensor can return simple values or more complex information like tables. For each type of information, one or more displays are provided. Displays are organized in worksheets that can be saved and loaded independently from each other. So, KSysguard is not only a simple task manager but also a very powerful tool to control large server farms.


Fig.05 KDE System Guard

Fig.05 KDE System Guard {Image credit: Wikipedia}

See the KSysguard handbook for detailed usage.


#20: Gnome System Monitor - Real-time Systems Reporting and Graphing


The System Monitor application enables you to display basic system information and monitor system processes, usage of system resources, and file systems. You can also use System Monitor to modify the behavior of your system. Although not as powerful as the KDE System Guard, it provides the basic information which may be useful for new users:

  • Displays various basic information about the computer's hardware and software.
  • Linux Kernel version
  • GNOME version
  • Hardware
  • Installed memory
  • Processors and speeds
  • System Status
  • Currently available disk space
  • Processes
  • Memory and swap space
  • Network usage
  • File Systems
  • Lists all mounted filesystems along with basic information about each.

Fig.06 The Gnome System Monitor application

Fig.06 The Gnome System Monitor application

Bonus: Additional Tools


A few more tools:

  • nmap - scan your server for open ports.
  • lsof - list open files, network connections and much more.
  • ntop web based tool - ntop is the best tool to see network usage in a way similar to what top command does for processes i.e. it is network traffic monitoring software. You can see network status, protocol wise distribution of traffic for UDP, TCP, DNS, HTTP and other protocols.
  • Conky - Another good monitoring tool for the X Window System. It is highly configurable and is able to monitor many system variables including the status of the CPU, memory, swap space, disk storage, temperatures, processes, network interfaces, battery power, system messages, e-mail inboxes etc.
  • GKrellM - It can be used to monitor the status of CPUs, main memory, hard disks, network interfaces, local and remote mailboxes, and many other things.
  • vnstat - vnStat is a console-based network traffic monitor. It keeps a log of hourly, daily and monthly network traffic for the selected interface(s).
  • htop - htop is an enhanced version of top, the interactive process viewer, which can display the list of processes in a tree form.
  • mtr - mtr combines the functionality of the traceroute and ping programs in a single network diagnostic tool.

Did I miss something? Please add your favorite system motoring tool in the comments.