MRTG Introduction
MRTG is wonderful tool. You can use it to monitor traffic on your
router or leased server located at remote IDC. Since it is written in
Perl and some code in C language, it is portable and high performance
tool.
What is MRTG?
As explained in official mrtg(1) man page "The Multi Router Traffic
Grapher (MRTG) is a tool to monitor the traffic load on network-links.
MRTG generates HTML pages containing GIF images which provide a LIVE
visual representation of this traffic." Here is public view of my
own
site. Please note following discussion based upon Red Hat Linux Enterprise version 3 update 2 and RHEL v4.0.
What is SNMP and why should I care?
SNMP is Simple Network Management Protocol. It is use to manage IP
network devices such as servers, routers, switches etc. Administrator
can find or manage network performance, solve problem or even optimize
Assumptions
These installation instructions assume you have:
Step # 2 : Determine if snmp server is running or not
Run 'ps' command to see if snmp server is running or not:
# ps -aux | grep snmp
Output:
root 5512 0.0 2.3 5872 3012 pts/0 S 22:04 0:00 /usr/sbin/snmpd
Alternatively, you can try any of the following two commands as well:
# lsof -i :199
Output:
COMMAND PID USER FD TYPE DEVICE SIZE NODE NAME
snmpd 5512 root 4u IPv4 34432 TCP *:smux (LISTEN)
OR try out netstat command:
# netstat -natv | grep ':199'
Output:
tcp 0 0 0.0.0.0:199 0.0.0.0:* LISTEN
If you found service is running or listing on port 199 then please see
step #3; otherwise start service using following command:
# service snmpd start
Make sure snmpd service starts automatically, when linux comes us (add snmpd service):
# chkconfig --add snmpd
Step # 3 : Make sure snmp server configured properly
Run snmpwalk utility to request for tree of information about network
entity. In simple words query snmp server for your IP address (assigned
to eth0, eth1, lo etc):
# snmpwalk -v 1 -c public localhost IP-MIB::ipAdEntIfIndex
ip.ipAddrTable.ipAddrEntry.ipAdEntIfIndex.127.0.0.1 = 1
ip.ipAddrTable.ipAddrEntry.ipAdEntIfIndex.192.168.0.3 = 2
If you can see your IP address then please proceed to step 4; else it is a time to configure snmp server as follows (by default RHEL and RH 8/9 are not
configured for snmp server for security reason):
**********Configure SNMP*****************
(1) Edit file /etc/snmp/snmpd.conf using text editor:
# vi /etc/snmp/snmpd.conf
Change/Modify line(s) as follows:
Find following Line:
com2sec notConfigUser default public
Replace with (make sure you replace 192.168.0.0/24 replace with your network IPs) following lines:
com2sec local localhost public
com2sec mynetwork 192.168.0.0/24 public
Scroll down bit and change:
Find Lines:
group notConfigGroup v1 notConfigUser
group notConfigGroup v2c notConfigUser
Replace with:
group MyRWGroup v1 local
group MyRWGroup v2c local
group MyRWGroup usm local
group MyROGroup v1 mynetwork
group MyROGroup v2c mynetwork
group MyROGroup usm mynetwork
Again scroll down bit and locate following line:
Find line:
view systemview included system
Replace with:
view all included .1 80
Again scroll down bit and change:
Find line:
access notConfigGroup "" any noauth exact systemview none none
Replace with:
access MyROGroup "" any noauth exact all none none
access MyRWGroup "" any noauth exact all all none
Scroll down bit and change:
Find lines:
syslocation Unknown (edit /etc/snmp/snmpd.conf)
syscontact Root (configure /etc/snmp/snmp.local.conf)
Replace with (make sure you supply appropriate values):
syslocation Linux (RH3_UP2), Home Linux Router.
syscontact Vivek G Gite <vivek@nixcraft.com>
For your convenient, here is my /etc/snmp/snmpd.conf file. Feel free to use this file. Make sure you make backup of your existing file if you use this file as it is.
Start your snmp server and test it:
(a) Make sure when linux comes up snmpd always starts:
# chkconfig snmpd on
(b) Make sure service start whenever Linux comes up (after reboot):
# service snmpd start
(c) Finally test your snmp server:
# snmpwalk -v 1 -c public localhost IP-MIB::ipAdEntIfIndex
Step # 4 : Install mrtg if not installed
Mrtg software may install during initial installation; you can verify if MRTG installed or not with following RPM command:
#rpm -qa | grep mrtg
If mrtg already installed please see
step # 5; else use
rpmfind.net to find MRTG rpm or up2date command to install MRTG software:
# up2date -v -i mrtg
Fedora Linux user can use yum command as follows to install MRTG:
# yum install mrtg
Step # 5 : Commands to Configure mrtg
(a) Create document root to store mrtg graphs/html pages:
# mkdir -p /var/www/html/mymrtg/
(b) Run any one of the following cfgmaker command to create mrtg configuration file:
# cfgmaker --global 'WorkDir: /var/www/html/mymrtg' --output /etc/mrtg/mymrtg.cfg public@localhost
OR (make sure your FQDN resolves, in following example i'm using rh9.test.com which is my router FQDN address)
# cfgmaker --global 'WorkDir: /var/www/html/mymrtg' --output /etc/mrtg/mymrtg1.cfg public@rh9.test.com
(c) Create default index page for your MRTG configuration:
# indexmaker --output=/var/www/html/mymrtg/index.html /etc/mrtg/mymrtg.cfg
(d) Copy all tiny png files to your mrtg path:
# cp -av /var/www/html/mrtg/*.png /var/www/html/mymrtg/
Step # 6 First test run of mrtg
(a) Run mrtg command from command line with your configuration file:
# mrtg /etc/mrtg/mymrtg.cfg
Note: You may get few warning message for first time; ignore them.
(b) Fire your favorite web browser (like FireFox :D ) and type url http://www.your.com/mymrtg/ or http://your-ip/mymrtg/
Step # 7 Create crontab entry so that mrtg graph / images get generated every 5 minutes
(a) Login as a root user or login as a mrtg user and type following command:
# crontab -e
(b) Add mrtg cron job entry to configuration file (append following line to it):
*/5 * * * * /usr/bin/mrtg /etc/mrtg/mymrtg.cfg --logging /var/log/mrtg.log
Save file and you are done with MRTG config issues :)
Step # 8 Block ports 161 & 162 at firewall
You do not want to give access to everyone to your snmp server for
security reasons. SNMP server uses UDP 161, 162 ports for communication.
Use Linux IPTABLES firewall to restrict access to SNMP server
(a) Allow outgoing SNMP server request from your Linux computer. This
is useful when you query remote host/router (replace SERVER IO with
your real IP):
SERVER="xxx.xxx.xxx.xxx"
iptables -A OUTPUT -p udp -s $SERVER --sport 1024:65535 -d 0/0 --dport 161:162 -m state --state NEW,ESTABLISHED -j ACCEPT
iptables -A INPUT -p udp -s 0/0 --sport 161:162 -d $SERVER --dport 1024:65535 -m state --state ESTABLISHED -j ACCEPT
(b
)Allow incoming SNMP client request via iptables. This is useful when
you wish to accept queries for rest of the world (replace SERVER IP with
your real IP):
SERVER="xxx.xxx.xxx.xxx"
iptables -A INPUT -p udp -s 0/0 --sport 1024:65535 -d $SERVER --dport 161:162 -m state --state NEW,ESTABLISHED -j ACCEPT
iptables -A OUTPUT -p udp -s $SERVER --sport 161:162 -d 0/0 --dport 1024:65535 -m state --state ESTABLISHED -j ACCEPT
Pleae
note that above two are just SNMP specific iptables rules. Please
consult iptables(8) man page for complete information on iptables
tep # 9 Optional: Protect your MRTG graphs/html pages with password protected directory
Once again, you would like to restrict access to your MRTG reports.
This can easily accomplished with Apache webserver's .htaccess file. If
you are on webhosting server with control panel (such as ensim or plesk)
then you can use control panel itself to create password-protected
directory.
Below is process outlined to protect graphs using apache's .htaccess file and htpasswd command:
Step # 1: Create .htaccess file in /var/www/html/mymrtg/ directory (add text as follows):
vi /var/www/html/mymrtg/.htaccess
Add following text to file:
AuthName "MRTG Graphs/Html restricted access"
AuthType Basic
AuthUserFile /var/members/.htpasswd
require user mrtgadmin
Step # 2: Create a user and password name (-c assumes first time you are using .htpasswd file):
# htpasswd -c /var/members/.htpasswd mrtgadmin
**********************************************************
OUTPUT:
Traffic Analysis for DOT COM INFOWAY LTD.
| Max Speed: | 2048 Kbps |
| Port@Router/Switch: | \GigabitEthernet5/1/0.3507:@CHN-ISP-ACC-RTR-172 |
| Wan Ip: | 182.72.163.152/30 |
The statistics were last updated
Friday, 8 June 2012 at 15:24,
at which time
'CHN-ISP-ACC-RTR-172' had been up for
76 days, 10:05:21.
`Daily' Graph (5 Minute Average)
|
Max |
Average |
Current |
| In |
1966.9 kb/s (96.0%) |
153.9 kb/s (7.5%) |
644.9 kb/s (31.5%) |
| Out |
313.6 kb/s (15.3%) |
21.6 kb/s (1.1%) |
124.4 kb/s (6.1%) |
`Weekly' Graph (30 Minute Average)
|
Max |
Average |
Current |
| In |
2046.8 kb/s (99.9%) |
286.0 kb/s (14.0%) |
450.1 kb/s (22.0%) |
| Out |
2033.3 kb/s (99.3%) |
62.6 kb/s (3.1%) |
90.5 kb/s (4.4%) |
`Monthly' Graph (2 Hour Average)
|
Max |
Average |
Current |
| In |
2047.2 kb/s (100.0%) |
304.7 kb/s (14.9%) |
581.2 kb/s (28.4%) |
| Out |
2033.3 kb/s (99.3%) |
60.3 kb/s (2.9%) |
102.5 kb/s (5.0%) |
`Yearly' Graph (1 Day Average)
|
Max |
Average |
Current |
| In |
2047.6 kb/s (100.0%) |
229.3 kb/s (11.2%) |
410.3 kb/s (20.0%) |
| Out |
2033.8 kb/s (99.3%) |
42.8 kb/s (2.1%) |
87.2 kb/s (4.3%) |
| GREEN ### |
Incoming Traffic in Bits per Second |
| BLUE ### |
Outgoing Traffic in Bits per Second |
| DARK GREEN ### |
Maximal 5 Minute Incoming Traffic |
| MAGENTA ### |
Maximal 5 Minute Outgoing Traffic |
error's:
[root@new-host mrtg]# mrtg /etc/mrtg/mrtg.cfg
-----------------------------------------------------------------------
ERROR: Mrtg will most likely not work properly when the environment
variable LANG is set to UTF-8. Please run mrtg in an environment
where this is not the case. Try the following command to start:
env LANG=C /usr/bin/mrtg /etc/mrtg/mrtg.cfg
-----------------------------------------------------------------------
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