Please note! We are migrating our documentation to https://securityonion.net/docs/. You can find the latest version of this page at: https://securityonion.net/docs/Firewall-old.
This page contains legacy information for versions of Setup older than securityonion-setup - 20120912-0ubuntu0securityonion201.
If you're running securityonion-setup - 20120912-0ubuntu0securityonion201 or newer, please see the current firewall documentation.
The default firewall configuration tool for Ubuntu is
ufw
. ufw
is enabled by default on Security Onion.Enable/Disable
Allow/Deny
example: allow port 9876 for Xplico
example: allow irc port range 6667 - 7000
example: deny https
What Ports Are Opened/Listening
example
example output
More Info
For more info you can visit the UFW documentation site
Note: Gufw is a GUI front end for the ufw.
Tightening the firewall on a master server
By default, older versions of Setup configure a master server to allow connections to the following ports from any IP address:
- 22 - SSH
- 443 - Squert/ELSA/CapMe
- 514 - Syslog
- 1514/udp - OSSEC
- 7734 - Sguil client
- 7736 - sensor connection to sguild
You may want to restrict those ports to only accepting connections from a subset of IP addresses.
NOTE! Before attempting any firewall changes, you should always ensure you have a backup plan should you accidentally block your own connection. So make sure that you have DRAC/KVM/physical or some other form of access.
Firewall rules to allow sensors to connect to master
First, add a rule like the following for each of your sensors (replacing a.b.c.d with the actual IP address of the sensor) to connect to ports 22 (SSH) and 7736 (sguild):
-OR-
If you're running Salt, then sensors need to connect to ports 4505/tcp and 4506/tcp:
Firewall rules to allow syslog devices
Next add a rule like the following for the IP addresses that will be sending syslog (port 514 tcp and udp):
Firewall rules to allow OSSEC agents
Next add a rule like the following for the IP addresses that will be running the OSSEC agent (port 1514 udp):
Firewall rules to allow analysts/administrators to connect to master
Criminal case download for pc. Then add a rule like the following for the IP addresses or subnet that you'll be using to connect to the master as an analyst/administrator to ports 22 (SSH), 443 (Squert/ELSA/CapMe), 7734 (Sguil client):
Remove default 'allow from Anywhere' rules
Once you've added these new rules, then you can remove the default 'allow from Anywhere' rules.
Tightening the firewall on a sensor
By default, a sensor allows connections to the following ports from any IP address:
- 22 - SSH
- 514 - Syslog
- 1514/udp - OSSEC
You may want to restrict those ports to only accepting connections from a subset of IP addresses.
NOTE! Before attempting any firewall changes, you should always ensure you have a backup plan should you accidentally block your own connection. So make sure that you have DRAC/KVM/physical or some other form of access.
Firewall rules to allow syslog devices
First, add a rule like the following for the IP addresses that will be sending syslog (port 514 tcp and udp):
Firewall rules to allow OSSEC agents
Next add a rule like the following for the IP addresses that will be running the OSSEC agent (port 1514 udp):
Firewall rules to allow analysts/administrators to connect to master
Then add a rule like the following for the IP addresses or subnet that you'll be using to connect to the sensor as an analyst/administrator to ports 22:
Remove default 'allow from Anywhere' rules
Once you've added these new rules, then you can remove the default 'allow from Anywhere' rules.
I need an rsyslog regex to forward all the messages containing the word 'FIREWALL' to a remote server. The original log format is:
Jul 24 16:33:09 FW02 kernel: [3456825.472985] FIREWALL_DENY_IN: IN=eth2 OUT=MAC=ff:ff:ff:ff:ff:ff:00:1b:78:e4:b3:24:08:00 SRC=10.101.103.193 DST=10.101.103.255 LEN=237 TOS=0x00 PREC=0x00 TTL=64 ID=0 DF PROTO=UDP SPT=51512 DPT=694 LEN=217
The required log format is to be without the kernel times:
Jul 24 16:33:09 FW02 kernel: FIREWALL_DENY_IN: IN=eth2 OUT=MAC=ff:ff:ff:ff:ff:ff:00:1b:78:e4:b3:24:08:00 SRC=10.101.103.193 DST=10.101.103.255 LEN=237 TOS=0x00 PREC=0x00 TTL=64 ID=0 DF PROTO=UDP SPT=51512 DPT=694 LEN=217
My experience with regex is basic. I was able to match the part I need to exclude with:
[ *[0-9]*.[0-9]*]
but that's all. The regex must be validated on http://www.rsyslog.com/regex/
alexalex
1 Answer
Disclaimer: I have no idea how rsyslog works, but perhaps the regex below can help
^([^[]*).*](.*)$
Submatch 1:
'Jul 24 16:33:09 FW02 kernel: '
Submatch 2:
' FIREWALL_DENY_IN: IN=eth2 OUT=MAC=ff:ff:ff:ff:ff:ff:00:1b:78:e4:b3:24:08:00 SRC=10.101.103.193 DST=10.101.103.255 LEN=237 TOS=0x00 PREC=0x00 TTL=64 ID=0 DF PROTO=UDP SPT=51512 DPT=694 LEN=217'
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I have to open up a group of ports.
Adding the single ports to (g)ufw was easy enough but I can't work out how to open the range
11200
-11299
. How do I do that?
user383919
![Deny Deny](/uploads/1/2/3/7/123711747/851898803.png)
Pieter BreedPieter Breed
5 Answers
You can specify port ranges to
ufw
(the command-line one), using :
(colon) to separate the lowest and the highest port in the range. For example:Note that the protocol part (
/tcp
or /udp
) is mandatory with port ranges.This works at least since Ubuntu 10.04.
Riccardo MurriRiccardo Murri13.9k55 gold badges4444 silver badges4949 bronze badges
Either
or if you need to use a from source ip range you must use full syntax
see:
OJ LaBoeufOJ LaBoeuf
I believe you can specify the range in the last tab of new rule, tick the checkbox at the bottom of the window to add more options (just to be safe). The range can be specified as 1000:1010 to open ports 1000-1010.
evgenyevgeny7,15222 gold badges2020 silver badges2727 bronze badges
The cleanest command line way I've seen is a little script like this:
Oli♦Oli227k9292 gold badges580580 silver badges777777 bronze badges
Its worth adding that if you want to restrict to a specific IP address which is allowed access to those ports you can use the following:
ufw allow proto tcp from 1.2.3.4 to any port 40000:40100
AntonyAntony
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Contents
Introduction
Prerequisites
Components Used
Conventions
Principles of Secure Operations
Cisco Firewalls as Security Devices
Security Policies and Configuration
Physical Security
Monitor Cisco Security Advisories and Responses
Leverage Authentication, Authorization, and Accounting.
Centralize Log Collection and Monitoring
Use Secure Protocols When Possible
Gain Traffic Visibility with NetFlow
Configuration Management
Securing the Management Plane
General Management Plane Hardening
Securing Management Sessions
Password Management
Login Password Retry Lockout
Disabling Password Recovery
Disable Unused Services
Network Time Protocol
Session Timeout
Using Management Interfaces
Memory Threshold Notifications
CPU Thresholding Notification
ICMP Packet Filtering
Securing Interactive Management Sessions
Encrypting Management Sessions
Console Port
Control Management Sessions
Control Management Sessions for Security Services Modules
Warning Banners
Using Authentication, Authorization, and Accounting.
TACACS+ Authentication
Authentication Fallback
TACACS+ Command Authorization
TACACS+ Command Accounting
Fortifying the Simple Network Management Protocol
SNMP Community Strings
SNMP MIBs
SNMP Version 3
Logging Best Practices
Send Logs to a Central Location
Logging Level
Disable Logging to Monitor Sessions and the Console
Use Buffered Logging
Configure Logging Time Stamps
Software Configuration Management
Securing the Control Plane
General Control Plane Hardening
ICMP Redirects
ICMP Unreachables
Limiting ICMP Responses
Securing Routing Protocols
Routing Protocol Authentication
Securing the Data Plane
General Data Plane Hardening
Filtering Transit Traffic with Transit ACLs
ACL Configuration Best Practices
Security Levels
Content and URL Filtering
Content Filtering
URL Filtering
Modular Policy Framework
Anti-Spoofing Protections
Unicast Reverse Path Forwarding
Antispoofing with Access Lists
Inspection
Enable Inspection for Nondefault Applications
ACLs to Block Private and Bogon Addresses
Denial of Service Protections
Threat Detection
Connection Limiting
TCP Normalizer
Botnet Protection
Limiting the CPU Impact of Data Plane Traffic
Traffic Identification and Traceback
IPv6 Traffic Filtering
High Availability Security
Best Practices Checklist
Management Plane Checks
Control Plane Checks
Data Plane Checks
Conclusion
Acknowledgments
References
Prerequisites
Components Used
Conventions
Principles of Secure Operations
Cisco Firewalls as Security Devices
Security Policies and Configuration
Physical Security
Monitor Cisco Security Advisories and Responses
Leverage Authentication, Authorization, and Accounting.
Centralize Log Collection and Monitoring
Use Secure Protocols When Possible
Gain Traffic Visibility with NetFlow
Configuration Management
Securing the Management Plane
General Management Plane Hardening
Securing Management Sessions
Password Management
Login Password Retry Lockout
Disabling Password Recovery
Disable Unused Services
Network Time Protocol
Session Timeout
Using Management Interfaces
Memory Threshold Notifications
CPU Thresholding Notification
ICMP Packet Filtering
Securing Interactive Management Sessions
Encrypting Management Sessions
Console Port
Control Management Sessions
Control Management Sessions for Security Services Modules
Warning Banners
Using Authentication, Authorization, and Accounting.
TACACS+ Authentication
Authentication Fallback
TACACS+ Command Authorization
TACACS+ Command Accounting
Fortifying the Simple Network Management Protocol
SNMP Community Strings
SNMP MIBs
SNMP Version 3
Logging Best Practices
Send Logs to a Central Location
Logging Level
Disable Logging to Monitor Sessions and the Console
Use Buffered Logging
Configure Logging Time Stamps
Software Configuration Management
Securing the Control Plane
General Control Plane Hardening
ICMP Redirects
ICMP Unreachables
Limiting ICMP Responses
Securing Routing Protocols
Routing Protocol Authentication
Securing the Data Plane
General Data Plane Hardening
Filtering Transit Traffic with Transit ACLs
ACL Configuration Best Practices
Security Levels
Content and URL Filtering
Content Filtering
URL Filtering
Modular Policy Framework
Anti-Spoofing Protections
Unicast Reverse Path Forwarding
Antispoofing with Access Lists
Inspection
Enable Inspection for Nondefault Applications
ACLs to Block Private and Bogon Addresses
Denial of Service Protections
Threat Detection
Connection Limiting
TCP Normalizer
Botnet Protection
Limiting the CPU Impact of Data Plane Traffic
Traffic Identification and Traceback
IPv6 Traffic Filtering
High Availability Security
Best Practices Checklist
Management Plane Checks
Control Plane Checks
Data Plane Checks
Conclusion
Acknowledgments
References
This document provides administrators and engineers guidance on securing Cisco firewall appliances, which increases the overall security of an end-to end architecture. The functions of network devices are structured around three planes: management, control, and data. This document is structured around security operations (best practices) and the three functional planes of a network. In addition, this document provides an overview of each included feature and references to related documentation. For the purposes of this document, all mentions of 'Cisco firewall' refer explicitly to the Cisco ASA Adaptive Security Appliances, though the concepts may apply to other firewall and security devices.
The three functional planes of a network each provide different functionality that needs to be protected.
- Management plane: The management plane manages traffic that is sent to the Cisco firewall device and is composed of applications and protocols such as SSH and Simple Network Management Protocol (SNMP).
- Control plane: The control plane of a network device processes the traffic that is paramount to maintaining the functionality of the network infrastructure. The control plane consists of applications and protocols between network devices, which include the interior gateway protocols (IGPs) such as the Enhanced Interior Gateway Routing Protocol (EIGRP) and Open Shortest Path First (OSPF).
- Data plane: The data plane forwards data through a network device. The data plane does not include traffic that is sent to the local Cisco firewall device.
In addition to providing configuration details, this document serves primarily as a best practices guide. Therefore, security concepts will be recommended, although the exact configuration details may not be provided. The feature will be explained in a manner that allows the security practitioner and decision makers to determine whether the feature is required in a certain environment.
Engineers and administrators should possess a conceptual understanding of Cisco firewall product software and the basic configuration options available.
Components Used
This document addresses the capabilities of Cisco ASA versions 8.x and later. Earlier releases of Cisco ASA Software may not include all features or capabilities outlined. Security practitioners who are using any Cisco firewall devices or ASA versions other than 8.x are advised to consult the release notes and documentation for the respective release regarding details and supported features.
Note: Some of the features referenced in this document may refer to, or show, examples of options that use strong encryption algorithms. Not all encryption algorithms may be available in all releases of Cisco firewall device software in all countries because of U.S. government export regulations.
Note: Some of the features referenced in this document may refer to, or show, examples of options that use strong encryption algorithms. Not all encryption algorithms may be available in all releases of Cisco firewall device software in all countries because of U.S. government export regulations.
Conventions
Refer to Cisco Technical Tips Conventions for more information on document conventions. Some command line examples in this document are wrapped to enhance readability.
Secure network operations are a substantial topic. Although most of this document is devoted to the secure configuration of a Cisco firewall device, configurations alone do not completely secure a network. The operational procedures in use on the network contribute as much to security as the configuration of the underlying devices.
These topics contain operational recommendations that administrators and engineers are advised to implement. These topics highlight specific critical areas of network operations and are not comprehensive.
These topics contain operational recommendations that administrators and engineers are advised to implement. These topics highlight specific critical areas of network operations and are not comprehensive.
Cisco Firewalls as Security Devices
Cisco firewalls provide advanced stateful firewall and VPN concentrator functionality in one device. In addition, some models offer an integrated intrusion prevention system (IPS) module or an integrated content security and control (CSC) module. Cisco firewall platforms include many advanced features, such as multiple security contexts (similar to virtualized firewalls), transparent (Layer 2) firewall, or routed (Layer 3) firewall operation, advanced inspection engines, IP Security (IPsec) VPN, SSL VPN, and clientless SSL VPN support.
Cisco firewalls protect network segments from unauthorized access by users or miscreants while also enforcing security policies and posture.
Cisco firewalls protect network segments from unauthorized access by users or miscreants while also enforcing security policies and posture.
When discussing the networks connected to a firewall, the outside network is typically defined as being in front of the firewall (an unsecured area), while the inside network is protected (by default) and resides behind the firewall-a trusted area, and a demilitarized zone (DMZ), while behind the firewall, allows limited access to outside (external) and inside (internal) users. Because Cisco ASA allows administrators and engineers to configure many interfaces with varied security policies, these interface terms/names are used only in a general sense.
There are key details that establish a firewall as a firewall and not a Layer 3 forwarding device. The Cisco firewall performs numerous intrinsic functions to ensure the security of an environment. These functions include, but are not limited to, the following:
- Stateful inspection
- Layer 2-7 protocol inspection (application protocol visibility)
- TCP normalizer functions
- Connection limits
These are key functions that differentiate a Cisco firewall from a standard Layer 3 device. New vegas perk every level mod.
For further details see the Cisco ASA 5500 Series Configuration Guide.
Security Policies and Configuration
Firewall Deny The Parket Proto=6
Security policies are the top tier of formalized security documents. These high-level documents take into account a risk assessment, and subsequently offer general statements regarding the organization's assets and resources and the level of protection they should have. Furthermore, security policies do not provide detailed specifics on how to accomplish the stated goals. Those details are captured in the subsequent security standards, baselines, and procedure documents.
A security policy determines the standards and rules that an environment/organization must adhere to. This policy also dictates which architecture solutions should be adopted for a given environment. The policy should be used as a high-level guide when pursuing firewall configuration details, including which traffic should be permitted to pass through the firewall to access another network and which traffic should not be permitted to pass. The Cisco ASA leverages the construct of 'Security Levels' to allow (or deny) the flow of traffic from one interface to another. Each interface must have a security level assigned from 0 (lowest) to 100 (highest). For example, you should assign your most secure network, such as the inside host network, to level 100. While the outside network connected to the Internet can be level 0. Other networks, such as DMZs can be in between. You can assign interfaces to the same security level. By default, Cisco ASA allows traffic to flow freely from a higher security level interface to a lower security level interface. For more details on Cisco ASA security levels, see the Security Levels section of this document. Administrators and engineers can apply actions to traffic to customize and/or adjust the firewall to adhere to stated security policies.
Note: An organization's established security policies, and not product features, should be the key factor when determining configuration details.
For further details, see the Cisco ASA 5500 Series Configuration Guide in addition to the Resources section of this document.
A security policy determines the standards and rules that an environment/organization must adhere to. This policy also dictates which architecture solutions should be adopted for a given environment. The policy should be used as a high-level guide when pursuing firewall configuration details, including which traffic should be permitted to pass through the firewall to access another network and which traffic should not be permitted to pass. The Cisco ASA leverages the construct of 'Security Levels' to allow (or deny) the flow of traffic from one interface to another. Each interface must have a security level assigned from 0 (lowest) to 100 (highest). For example, you should assign your most secure network, such as the inside host network, to level 100. While the outside network connected to the Internet can be level 0. Other networks, such as DMZs can be in between. You can assign interfaces to the same security level. By default, Cisco ASA allows traffic to flow freely from a higher security level interface to a lower security level interface. For more details on Cisco ASA security levels, see the Security Levels section of this document. Administrators and engineers can apply actions to traffic to customize and/or adjust the firewall to adhere to stated security policies.
Note: An organization's established security policies, and not product features, should be the key factor when determining configuration details.
For further details, see the Cisco ASA 5500 Series Configuration Guide in addition to the Resources section of this document.
Physical Security
The security of a device should begin with a progression up the Open Systems Interconnection (OSI) reference model, beginning with the physical layer. Though obvious, the details surrounding the physical security of a device are often overlooked. Physical security, as it applies to a firewall, refers to ensuring the device is placed in a physical location that is restricted to authorized personnel. Most often firewalls are installed in a restricted-access room; however, many levels of personnel have access to the room. Therefore, consider establishing and using role-based access control (RBAC). In this scenario, in addition to having the firewall placed in a restricted-access room, the firewall may also be housed in a locking rack/sector in the restricted room.
Furthermore, environmental factors should also be verified because most Cisco firewalls have an operating temperature of 32 to 104 degrees F (0 to 40 degrees C). For details regarding the environmental factors and statistics, refer to the product data sheets for the respective firewall on the Cisco website.
Furthermore, environmental factors should also be verified because most Cisco firewalls have an operating temperature of 32 to 104 degrees F (0 to 40 degrees C). For details regarding the environmental factors and statistics, refer to the product data sheets for the respective firewall on the Cisco website.
Monitor Cisco Security Advisories and Responses
The Cisco Product Security Incident Response Team (PSIRT) creates and maintains publications, commonly referred to as PSIRT advisories, for security-related issues in Cisco products. The method for communication of less-severe issues is the Cisco Security Response. Security advisories and responses are available at http://www.cisco.com/go/psirt.
Additional information about these communication vehicles is available in the Cisco Security Vulnerability Policy.
To maintain a secure network, one must be aware of the Cisco advisories and responses that have been released. Moreover, one must have knowledge of a vulnerability before evaluating the threat it can pose to a network. Refer to Risk Triage for Security Vulnerability Announcements for assistance with this evaluation process.
Additional information about these communication vehicles is available in the Cisco Security Vulnerability Policy.
To maintain a secure network, one must be aware of the Cisco advisories and responses that have been released. Moreover, one must have knowledge of a vulnerability before evaluating the threat it can pose to a network. Refer to Risk Triage for Security Vulnerability Announcements for assistance with this evaluation process.
Leverage Authentication, Authorization, and Accounting
The authentication, authorization, and accounting (AAA) framework is vital to securing network devices. The AAA framework provides authentication of management sessions and can also limit users to specific, administrator-defined commands in addition to logging all commands entered by all users. See the Leverage Authentication, Authorization, and Accounting section of this document for more information about using AAA. Also, it is highly recommended to implement least privilege, in which every program and every user of the system should operate using the least set of privileges necessary to complete the job.
Centralize Log Collection and Monitoring
To understand existing, emerging, and historic events related to security incidents, an organization needs a unified strategy for event logging and correlation. This strategy must employ logging from all network devices and use prepackaged and customizable correlation capabilities.
After centralized logging is implemented, one must develop a structured approach to log analysis and incident tracking. Based on the needs of the organization, this approach can range from a simple, diligent review of log data to advanced rule-based analysis.
See the Logging Best Practices section of this document for more information about implementing logging on Cisco firewall devices.
After centralized logging is implemented, one must develop a structured approach to log analysis and incident tracking. Based on the needs of the organization, this approach can range from a simple, diligent review of log data to advanced rule-based analysis.
See the Logging Best Practices section of this document for more information about implementing logging on Cisco firewall devices.
Use Secure Protocols When Possible
Many protocols are used to carry sensitive network management data. One must use secure protocols whenever possible. A secure protocol choice includes using SSH instead of Telnet so that both authentication data and management information are encrypted. In addition, one must use secure file transfer protocols when copying configuration data. An example is the use of the Secure Copy Protocol (SCP) in place of FTP or TFTP.
See the Securing Interactive Management Sessions section of this document for more information about the secure management of Cisco firewall devices.
See the Securing Interactive Management Sessions section of this document for more information about the secure management of Cisco firewall devices.
Gain Traffic Visibility with NetFlow
Cisco firewalls support NetFlow version 9 services. In particular, the Cisco ASA implementation of NetFlow Secure Event Logging (NSEL) is a stateful, IP flow tracking method that exports only records that indicate significant events in a flow. In stateful flow tracking, tracked flows go through a series of state changes. NSEL events are used to export data about flow status and are triggered by the event that caused the state change.
The significant events that are tracked include flow-create, flow-teardown, and flow-denied (excluding flows that are denied by EtherType access control lists [ACLs]). Each NSEL record has an event ID and an extended event ID field, which describes the flow event.
For details regarding NSEL on Cisco firewalls, refer to the Configuring Network Secure Event Logging (NSEL) section of the Cisco ASA Configuration Guide.
The significant events that are tracked include flow-create, flow-teardown, and flow-denied (excluding flows that are denied by EtherType access control lists [ACLs]). Each NSEL record has an event ID and an extended event ID field, which describes the flow event.
For details regarding NSEL on Cisco firewalls, refer to the Configuring Network Secure Event Logging (NSEL) section of the Cisco ASA Configuration Guide.
Configuration Management
Configuration management, also known as change management, is a process by which configuration changes are proposed, reviewed, approved, and deployed. In the context of a Cisco firewall device configuration, two additional aspects of configuration management are critical: configuration archiving and security.
One can use configuration archives to roll back changes that are made to network devices. In a security context, configuration archives can also be used to determine which security changes were made and when these changes occurred. In conjunction with AAA log data, this information can assist in the security auditing of network devices.
The configuration of a Cisco firewall device contains many sensitive details. Usernames, passwords, and the contents of ACLs are examples of this type of information. The repository used to archive Cisco firewall device configurations needs to be secured. Insecure access to this information can undermine the security of the entire network.
One can use configuration archives to roll back changes that are made to network devices. In a security context, configuration archives can also be used to determine which security changes were made and when these changes occurred. In conjunction with AAA log data, this information can assist in the security auditing of network devices.
The configuration of a Cisco firewall device contains many sensitive details. Usernames, passwords, and the contents of ACLs are examples of this type of information. The repository used to archive Cisco firewall device configurations needs to be secured. Insecure access to this information can undermine the security of the entire network.
The management plane consists of functions that achieve the management goals of the network. This includes interactive management sessions using SSH in addition to statistics gathering with SNMP or NetFlow. When considering the security of a network device, it is critical that the management plane be protected. If a security incident can undermine the functions of the management plane, the administrator may not be able to 'recover' (stabilize) the network.
The Management Plane sections of this document provide the security features and configurations available in Cisco ASA Software that help fortify the management plane.
The Management Plane sections of this document provide the security features and configurations available in Cisco ASA Software that help fortify the management plane.
General Management Plane Hardening
The purpose of the management plane is to provide the capability to access, configure, and manage a device and to monitor its operations and the network on which it is deployed. The management plane receives and sends traffic for these functions. One must secure both the management plane and control plane of a device because operations of the control plane directly affect operations of the management plane. The following is a list of common protocols and tools used by the management plane:
- SNMP
- Telnet
- SSH
- FTP
- TFTP
- SCP
- TACACS+
- RADIUS
- NetFlow
- Network Time Protocol (NTP)
- Syslog
Steps must be taken to ensure the survival of the management and control planes during security incidents. If one of these planes is successfully exploited, all planes can be compromised. Ghost windows 7 32 bit auto driver all programs 2018. Moreover, exploitation can heavily impact the incident handling process, specifically regarding postmortem and lessons learned.
Securing Management Sessions
Password Management
Firewall Deny The Parket Prototype
Passwords control access to resources and devices when they are required for request authentication. When a request for access to a resource or device is received, the request is challenged for verification of the password and identity. Access can be granted, denied, or limited based on the result. As a security best practice, passwords must be managed with a TACACS+ or RADIUS authentication server. However, note that a locally configured password for privileged access will still be needed in the event of TACACS+ or RADIUS services failure. A device may also have other password information present in its configuration. Examples include an NTP key, SNMP community string, and failover or routing protocol keys.
The enable password command is used to set the password that grants privileged administrative access to the Cisco firewall system. This command uses Message Digest 5 (MD5) for password hashing. This algorithm has had considerable public review and is not known to be reversible. However, the algorithm is subject to dictionary attacks, in which an attacker attempts various dictionary words in addition to other lists of candidate passwords to search for a match. For resilience against dictionary attacks, a salt value is added to the password before it is hashed and stored. As a general precaution, configuration files must be securely stored and shared only with trusted individuals.
User passwords are also hashed using the MD5 algorithm after they have been concatenated with a salt value that provides resilience against dictionary attacks.
Other Cisco firewall passwords (such as OSPF keys and VPN keys) are not encrypted on the firewall device by default, but the configured passwords will not be shown in the show running-configuration command output. Any Cisco firewall configuration file that contains passwords must be treated with care.
Beginning with Cisco ASA version 8.3, the firewall can store plaintext passwords in an encrypted format. The encryption algorithm is the Advanced Encryption Standard (AES). The feature requires the definition of an encryption passphrase that is used to encrypt and decrypt the keys/passwords. Keys that can be encrypted include keys for routing protocol authentication, VPN, failover, AAA servers, logging, shared licenses, and more. Refer to Configuring the Master Passphrase section of the Cisco ASA 5500 Series Configuration Guide for further information on the feature
The enable password command is used to set the password that grants privileged administrative access to the Cisco firewall system. This command uses Message Digest 5 (MD5) for password hashing. This algorithm has had considerable public review and is not known to be reversible. However, the algorithm is subject to dictionary attacks, in which an attacker attempts various dictionary words in addition to other lists of candidate passwords to search for a match. For resilience against dictionary attacks, a salt value is added to the password before it is hashed and stored. As a general precaution, configuration files must be securely stored and shared only with trusted individuals.
User passwords are also hashed using the MD5 algorithm after they have been concatenated with a salt value that provides resilience against dictionary attacks.
Other Cisco firewall passwords (such as OSPF keys and VPN keys) are not encrypted on the firewall device by default, but the configured passwords will not be shown in the show running-configuration command output. Any Cisco firewall configuration file that contains passwords must be treated with care.
Beginning with Cisco ASA version 8.3, the firewall can store plaintext passwords in an encrypted format. The encryption algorithm is the Advanced Encryption Standard (AES). The feature requires the definition of an encryption passphrase that is used to encrypt and decrypt the keys/passwords. Keys that can be encrypted include keys for routing protocol authentication, VPN, failover, AAA servers, logging, shared licenses, and more. Refer to Configuring the Master Passphrase section of the Cisco ASA 5500 Series Configuration Guide for further information on the feature
Firewall Deny The Parket Proto 2
Login Password Retry Lockout
The ASA allows an administrator to lock out a local user account after a configured number of unsuccessful login attempts. Once a user is locked out, the account is locked until the administrator unlocks it. An authorized user who is configured with privilege level 15 cannot be locked out with this feature. The number of users with privilege level 15 must be kept to a minimum.
Note that authorized users can lock themselves out of a device if the number of unsuccessful login attempts is reached. In addition, a malicious user can create a denial of service (DoS) condition with repeated attempts to authenticate with a valid username.
This example shows how to enable the login password retry lockout feature:
Note that authorized users can lock themselves out of a device if the number of unsuccessful login attempts is reached. In addition, a malicious user can create a denial of service (DoS) condition with repeated attempts to authenticate with a valid username.
This example shows how to enable the login password retry lockout feature: