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Configuring Firewall Log Files

Updated: February 18, 2010

Applies To: Windows 7, Windows Server 2008 R2

You can enable logging in Windows Firewall with Advanced Security to create a text file that contains information about which network connections the firewall allows and drops. You can create the following types of log files:

Before you can view firewall logs, you must configure Windows Firewall with Advanced Security to create log files.

  1. In the console tree of the Windows Firewall with Advanced Security snap-in, click Windows Firewall with Advanced Security, and then click Properties in the Actions pane.

  2. Click the tab of the profile for which you want to configure logging (Domain, Private, or Public), and then click Customize.

  3. Specify a name and location.

  4. Specify a log file size limit (Between 1 and 32767 Kbytes).

  5. Click Yes for Log dropped packets.

  6. Click Yes for Log successful connections and then click OK.


To view the firewall log file

Open Explorer to the path and filename you chose in the previous procedure, "To configure logging for a profile". To access the firewall log, you must be an administrator of the local computer.Windows Firewall with Advanced Security

You can view the log file in Notepad or any program that can open a text file.


Interpreting the firewall log file

The following log information is collected. Some data in the log file applies to only certain protocols (TCP flags, ICMP type and code, etc.), and some data applies only to dropped packets (size).

 

Fields Description Example

Date

Displays the year, month, and day that the recorded transaction occurred. Dates are recorded in the format YYYY-MM-DD, where YYYY is the year, MM is the month, and DD is the day.

2006-3-27

Time

Displays the hour, minute, and second when the recorded transaction occurred. Times are recorded in the format: HH:MM:SS, where HH is the hour in 24-hour format, MM is the minute, and SS is the second.

21:36:59

Action

Indicates the operation that was observed by the firewall. The actions available to the firewall are OPEN, CLOSE, DROP, and INFO-EVENTS-LOST. An INFO-EVENTS-LOST action indicates the number of events that occurred but that were not recorded in the log.

OPEN

Protocol

Displays the protocol that was used for the communication. A protocol entry can also be a number for packets that are not using TCP, UDP, or ICMP.

TCP

src-ip

Displays the IP address of the sending computer.

XXX.XXX.X.XX

dst-ip

Displays the IP address of the destination computer.

XXX.XXX.X.XX

src-port

Displays the source port number of the sending computer. A src-port entry is recorded in the form of a whole number, between 1 and 65,535. Only TCP and UDP display a valid src-port entry. All other protocols display a src-port entry of -.

4039

dst-port

Displays the port number of the destination computer. A dst-port entry is recorded in the form of a whole number, between 1 and 65,535. Only TCP and UDP display a valid dst-port entry. All other protocols display a dst-port entry of -.

53

size

Displays the packet size in bytes.

-

tcpflags

Displays the TCP control flags that are found in the TCP header of an IP packet:

  • Ack. Acknowledgment field significant

  • Fin. No more data from sender

  • Psh. Push function

  • Rst. Reset the connection

  • Syn. Synchronize sequence numbers

  • Urg. Urgent Pointer field significant

A flag appears as a single uppercase initial of the flagname. For example, the Fin flag appears as F, the single uppercase initial of the flagname.

AFP

tcpsyn

Displays the TCP sequence number in the packet.

1315819770

tcpack

Displays the TCP acknowledgment number in the packet.

0

tcpwin

Displays the TCP window size of the packet in bytes.

64240

icmptype

Displays a number that represents the Type field of the ICMP message.

8

icmpcode

Displays a number that represents the Code field of the ICMP message.

0

info

Displays an information entry that depends on the type of action that occurred. For example, an INFO-EVENTS-LOST action creates an entry for the number of events that occurred but were not recorded in the log since the time of the last occurrence of this event type.

23

noteNote
A hyphen (-) is used for fields where no information is available for an entry.

You can create two custom log files, one to view network statistics (lists all listening ports) and the other to view the task list of either programs or services. The task list will provide the process identifier (PID) of the event which you can look up in the network statistics file for details. The procedure to create these two files is as follows:

  1. At the command prompt, type netstat -ano > netstat.txt, and then press ENTER.

  2. At the command prompt, type tasklist > tasklist.txt, and then press ENTER. If you want to create a text file for services rather than programs, at the command prompt, type tasklist /svc > tasklist.txt.

  3. Open the tasklist.txt and the netstat.txt files.

  4. In the tasklist.txt file, write down the Process Identifier (PID) for the process you are troubleshooting. Compare the PID with that in the Netstat.txt file. Write down the protocol that is used. The information about the protocol used can be useful when reviewing the information in the firewall log file.

Netstat.txt

Proto Local Address Foreign Address State PID

TCP 0.0.0.0:XXX 0.0.0.0:0 LISTENING 122

TCP 0.0.0.0:XXXXX 0.0.0.0:0 LISTENING 322

Tasklist.txt

Image Name PID Session Name Session# Mem Usage

==================== ======== ================ =========== ============

svchost.exe 122 Services 0 7,172 K

XzzRpc.exe 322 Services 0 5,104 K

noteNote
The actual IP addresses have been changed to (X), and RPC service to (z).

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