Tag Archives: HowTo

Windows Server 2008 / IIS 7.5: client source port logging

Many countermeasures taken by ISPs to face IPv4 exhaustion (DS-Lite, NAT64, NAT44, CGN) need more than the old IP-address/timestamp couple to uniquely identify an end-user on Internet. Even with a full logging of activities and sessions an ISP can’t trace a specific user if no source TCP/UDP port is given. So content providers, whether large or small, need to enable clients source port logging; it doesn’t matter if they run an enormous e-commerce website or a small blog like this, if they want to provide Law Enforcement Agencies (LEAs) a set of information capable of uniquely trace a user they need client source port logging.

Many software products have simple builtin configuration commands to accomplish this task, here I write how to enable this feature under Microsoft Windows Server 2008 R2 – IIS 7.5.

Advanced Logging IIS extension

The IIS builtin logging module doesn’t allow client source port logging, so an extension is needed: Advanced Logging. Once installed a new icon appears in the IIS Management Console:

IIS Advanced Logging icon

IIS Advanced Logging icon

Enable client port logging

Configuration can be done at any level: global, web site, directory. Open the Advanced Logging icon then, in the Actions pane, click Enable Advanced Logging. Once enabled the feature you just need to add the client port to the list of logged fields: always from the Action pane click Edit Logging Fields, then the Add field button and use the following data:

Field ID: Client-IP
Source type: Server variables
Source name: REMOTE_PORT

Hit the OK button a couple of time and go back to the main window, where you find the default log definition named %COMPUTERNAME%-Server; double click it in order to open details then select your logging preferences, being careful to add the Client-IP field ID to the list of the selected ones (from the Selected Fields section click the Select Fields button and check it).

After you have done some activity on your web site you can check the log content clicking View log files from the Actions pane; client port will be there somewhere, depending on the fields sequence you have on the log definition Selected Fields list.

Cisco HSRP monitoring using SNMP

Cisco HSRP MIB is defined in CISCO-HSRP-MIB and CISCO-HSRP-EXT-MIB; for a basic SNMP monitoring the first MIB is more than enough.

The most important table in order to get HSRP status information is cHsrpGrpTable, where we can find as many cHsrpGrpEntry objects as HSRP groups configured in the router. Each cHsrpGrpEntry object represents the HSRP configuration and status for a given HSRP group number on a given interface; it has, so, a double index: SNMP interface ID and HSRP group number.

Here is an example of a snmpwalk over a router:

root@NMS:~# snmpwalk -v 2c -c public .
iso. = STRING: "cisco"
iso. = Gauge32: 255
iso. = INTEGER: 1
iso. = Gauge32: 0
iso. = INTEGER: 2
iso. = Gauge32: 0
iso. = Gauge32: 0
iso. = Gauge32: 3000
iso. = Gauge32: 10000
iso. = IpAddress:
iso. = INTEGER: 1
iso. = IpAddress:
iso. = IpAddress:
iso. = INTEGER: 6
iso. = Hex-STRING: 00 00 0C 07 AC 0A
iso. = INTEGER: 1

The first highlighted value is the SNMP interface ID: you can get the SNMP ID for a given interface using the show snmp mib ifmib ifindex command:

CiscoRouter#show snmp mib ifmib ifindex FastEthernet 0/1
Interface = GigabitEthernet0/1, Ifindex = 2.

The second highlighted value is the HSRP group, the one you use while configuring HSRP:

interface FastEthernet0/1
 standby 10 ip
 standby 10 priority 255

In order to monitor the HSRP group state you just have to grab the cHsrpGrpStandbyState parameter (OID iso., which can have one of the following values:

1: initial
2: learn
3: listen
4: speak
5: standby
6: active

In my previous example the router was in the active state.


Cisco.com: Hot Standby Router Protocol Features and Functionality



Wikipedia: HSRP

Zabbix: send SMS using gammu-smsd

Recently I needed to setup a Zabbix distribution with SMS notifications. I had a Momo Design MD-@ USB Internet key to be used as GSM modem, with a BT Italia (Vodafone) SIM card. I used the 1.8.5 version of Zabbix, installed using the apt tool on a Ubuntu 11.10.

The Zabbix built-in SMS notification system seemed to have a bug, which cause a triple notification to be sent on every trigger action (bug ID ZBX-3507), so I preferred to use an external (custom) script and a third party tool: gammu-smsd.

This daemon connects to the GSM modem and listens for an outgoing queue; when you need to send a message, you just have to “inject” it into its queue, then it does the rest.


As soon as I plugged the USB key into the server, Ubuntu recognized it:

Oct 27 13:57:08 MyMachineName kernel: [764858.260009] usb 4-1: new full speed USB device number 2 using uhci_hcd
Oct 27 13:57:08 MyMachineName kernel: [764858.481158] cdc_acm 4-1:1.0: ttyACM0: USB ACM device
Oct 27 13:57:08 MyMachineName kernel: [764858.484118] usbcore: registered new interface driver cdc_acm
Oct 27 13:57:08 MyMachineName kernel: [764858.484121] cdc_acm: USB Abstract Control Model driver for USB modems and ISDN adapters

Then I installed gammu-smsd and edited its configuration file:

apt-get install gammu-smsd
cat /etc/gammu-smsdrc

# Configuration file for Gammu SMS Daemon

# Gammu library configuration, see gammurc(5)
# Please configure this!
port = /dev/ttyACM0
connection = at
# Debugging
logformat = textall

# SMSD configuration, see gammu-smsdrc(5)
service = files
logfile = /var/log/gammu-smsd
# Increase for debugging information
debuglevel = 0
ReceiveFrequency = 300
# Paths where messages are stored
inboxpath = /var/spool/gammu/inbox/
outboxpath = /var/spool/gammu/outbox/
sentsmspath = /var/spool/gammu/sent/
errorsmspath = /var/spool/gammu/error/

The port parameter is the device where the modem is mapped. This may change on other system.

I changed the logfile parameter also, because by default it is configured to log to syslog. You need to give the right permissions to it:

chmod a+rw /var/log/gammu-smsd

The ReceiveFrequency is used to tell gammu-smsd how often to check for incoming SMS; by default it is every 1 second, but in my case I didn’t need to receive SMS, so I raised it to 5 minutes.

An important parameter is PIN on the [smsd] section: in my case I removed the PIN check from my SIM card, so I didn’t use it in the configuration file.

In order to avoid “Cannot open file” errors, I also granted access to the device to everyone:

chmod a+rw /dev/ttyACM0

At this time I reloaded gammu-smsd and tested the configuration:

/etc/init.d/gammu-smsd restart
echo "Test message" | gammu-smsd-inject TEXT 335123456

(replace 335123456 with your mobile phone number!)

The gammu-smsd-monitor utility let you to check your modem status too.

In order to rotate gammu-smsd log file, I wrote a logrotate.d configuration file too:

cat /etc/logrotate.d/gammu-smsd
/var/log/gammu-smsd {
    rotate 7

Zabbix configuration

As first I configured a new media type using the Zabbix administration front-end:

Administration / Media types -> Create Media Type

Description: SMS-via-gammu
Type: Script
Script name: sendsms

sendsms is the name of the external script I used for my custom notification system.

Then I configured the new media type for my Zabbix user:

Administration / Users -> select Users in the top right corner – edit your user Media: Add

Type: SMS-via-gammu
Send to: 335123456
When active, Use if severity: as you wish
Status: Enabled

Of course, I had an Action configured too, but for more information I suggest you to read about it on the official documentation page.

In order to configure Zabbix to use external notification scripts, I verified that the AlertScriptsPath was present in the configuration file:

cat /etc/zabbix/zabbix_server.conf | grep AlertScriptsPath

/etc/zabbix/alert.d is the directory where notifications script have to be.

Then I added the zabbix user to the gammu group, in order to give it the right permissions to inject messages into the outgoing gammu queue…

adduser zabbix gammu

… then I restarted Zabbix:

/etc/init.d/zabbix-server restart

This is the script I used to inject Zabbix notifications into the gammu outgoing queue (/etc/zabbix/alert.d/sendsms):


# $1    recipient
# $2    subject
# $3    message

TMPFILE=`mktemp -t`

echo "$3" >> $TMPFILE

cat $TMPFILE | gammu-smsd-inject TEXT $1

chmod a+x /etc/zabbix/alert.d/sendsms

At this time I tested it by creating a new trigger with fake values (temperature < 100 °C, or everything else could let an action to be raised).


Zabbix.com: Configuration page on the official documentation site

gammu-smsd: Gammu SMSD

NetFlow: installation and configuration of NFDUMP and NfSen on Debian

After the brief overview about the installation of flow-tools and FlowViewer, in this post I’d like to share my experience about the setup of a basic solution based on another pair of tools: NFDUMP and NfSen. As always on my posts, the starting point is a fresh Debian 5.0 setup.

UPDATE: you may be interested in FlowGraph too, a tool that allows to dynamically build graphs based on previously collected netflow data and to use them in a web-based front-end, adding details about Autonomous System Number holders, IPv4 and IPv6 prefixes, inet(6)num objects, netnames from RIPE Stat.

Read more …

NetFlow: how to install and configure flow-tools and FlowViewer on a fresh Debian setup

NetFlow is a very useful tool/protocol to monitor network traffic’s patterns. Many tools have been developed to collect and analyze NetFlow data, here I chose flow-tools and FlowViewer packages, and I would like to show how to get them work on a fresh Debian 5.0 (Lenny) setup.

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