Linux / Unix logtop: Realtime Log Line Rate Analyser

by on July 22, 2014 · 6 comments· LAST UPDATED July 23, 2014

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How can I analyze line rate taking log file as input on a Linux system? How do I find the IP flooding my Apache/Nginx/Lighttpd web-server on a Debian or Ubuntu Linux?

Tutorial details
DifficultyEasy (rss)
Root privilegesYes
Estimated completion timeN/A
You need to use a tool called logtop. It is a system administrator tool to analyze line rate taking log file as input. It reads on stdin and print a constantly updated result displaying, in columns in the following format:

Line number, count, frequency, and the actual line

How do install logtop on a Debian or Ubuntu based system?

Simply type the following apt-get command:
$ sudo apt-get install logtop
Sample outputs:

Reading package lists... Done
Building dependency tree
Reading state information... Done
The following NEW packages will be installed:
0 upgraded, 1 newly installed, 0 to remove and 3 not upgraded.
Need to get 15.7 kB of archives.
After this operation, 81.9 kB of additional disk space will be used.
Get:1 precise/universe logtop amd64 0.3-1 [15.7 kB]
Fetched 15.7 kB in 0s (0 B/s)
Selecting previously unselected package logtop.
(Reading database ... 114954 files and directories currently installed.)
Unpacking logtop (from .../logtop_0.3-1_amd64.deb) ...
Processing triggers for man-db ...
Setting up logtop (0.3-1) ...


The syntax is as follows:

logtop [OPTIONS] [FILE]
command | logtop
command1 | filter | logtop
command1 | filter | logtop [options] [file]


Here are some common examples of logtop.

Show the IP address flooding your LAMP server

Type the following command:

tail -f www.cyberciti.biz_access.log | cut -d' ' -f1 | logtop

Sample outputs:

Fig.01: logtop command in action

Fig.01: logtop command in action

See squid cache HIT and MISS log

tail -f cache.log | grep -o "HIT\|MISS" | logtop

To see realtime hit / miss ratio on some caching software log file, enter:
tail -f access.log | cut -d' ' -f1 | logtop -s 20000
The -s option set logtop to work with the maximum of K lines instead of 10000.

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{ 6 comments… read them below or add one }

1 Charles July 22, 2014 at 5:24 pm

This looks really cool, possibly invaluable during a DoS attack.

Any chance there’s instructions on how to install on FreeBSD? logtop is not in the ports collection :(


2 John July 22, 2014 at 6:38 pm

Agreed. Good tool to find out during a DoS attack. Download it from git repo and may be compile from source? ?


3 Rabin July 23, 2014 at 7:48 am

how is this diffrent then just using `sort | uniq -c`


4 Yordan Georgiev July 27, 2014 at 6:16 am

*** how is this different than just using `sort | uniq -c`
sudo cat /var/log/httpd/access_log | cut -d’ ‘ -f1 | logtop
2453 lines, 2453.00 lines/s
1 1213 1213.00
2 201 201.00
3 157 157.00 ::1
4 105 105.00
5 83 83.00
6 77 77.00
7 40 40.00
8 37 37.00
9 37 37.00
10 27 27.00


5 Marco July 23, 2014 at 8:18 am

Here is my guide to install it on CentOS 7 (should also apply to RHEL 7)


6 mauron85 August 11, 2014 at 8:58 pm

I believe that difference is that it works incrementaly. With uniq sort combo you have to proces whole log again. With this only inctlrements thanks to tail.


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