Snort Ids And Ips Toolkit Pdf
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- Snort IDS & IPS Toolkit pdf
- Snort IDS and IPS Toolkit by Brian Caswell
- Snort Intrusion Detection and Prevention Toolkit
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Snort IDS & IPS Toolkit pdf
What Is Intrusion Detection? How an IDS Works. What About Intrusion Protection? Solutions Fast Track. Frequently Asked Questions. All right, this might be a bit dramatic for a prelude to a discussion of intrusion detection, but most security administrators experience a moment of anxiety when a beeper goes off. Is this the big one? Did they get in? How many systems could have been compromised? What data was stored on or accessible by those systems? What sort of liability does this open us up to?
Are more systems similarly vulnerable? Is the press going to have a field day with a data leak? These and many other questions flood the mind of the well-prepared security administrator.
On the other hand, the ill-prepared security administrator, being totally unaware of the intrusion, experiences little anxiety. For him, the anxiety comes later. Okay, so how can a security-minded administrator protect his network from intrusions?
The answer to that question is quite simple. An intrusion detection system IDS can help to detect intrusions and intrusion attempts within your network, allowing a savvy admin to take appropriate mitigation and remediation steps.
A pure IDS will not prevent these attacks, but it will let you know when they occur. When we speak of intrusion detection, we are referring to the act of detecting an unauthorized intrusion by a computer on a network. This unauthorized access, or intrusion, is an attempt to compromise, or otherwise do harm, to other network devices. A body of American legislation surrounds what counts as a computer intrusion, but although the term computer intrusion is used to label the relevant laws, there is no single clear and useful definition of a computer intrusion.
Knowingly accessed a computer without authorization or exceeding authorized access is a common thread in several definitions. However, all the definitions go on to further require theft of government secrets, financial records, government data, or other such things. There is also a lack of legislative clarity regarding what access is. For example, a portscan gathers data about which ports on the target computer are listening, but does not attempt to use any services.
Nevertheless, some people argue that this constitutes accessing those services. A security scanner such as Nessus or Retina may check the versions of listening services and compare them against a database of known security vulnerabilities. This is more intrusive than a simple portscan, but merely reports the presence of vulnerabilities rather than actually exploiting them.
Is this accessing the service? Should it count as an intrusion? Finally, there are the blatant cases where the system is actually compromised. Most people would agree that this counts as an intrusion. For our purposes, we can define an intrusion as an unwanted and unauthorized intentional access of computerized network resources. An IDS is the high-tech equivalent of a burglar alarm, one that is configured to monitor information gateways, hostile activities, and known intruders.
This data can range from network packet analysis to the contents of log files from routers, firewalls, and servers, local system logs and access calls, network flow data, and more. At that point, the IDS can issue alarms or alerts, take various kinds of automated actions ranging from shutting down Internet links or specific servers to launching back-traces, and make other active attempts to identify attackers and collect evidence of their nefarious activities.
By analogy, an IDS does for a network what an antivirus software package does for files that enter a system: it inspects the contents of network traffic to look for and deflect possible attacks, just as an antivirus software package inspects the contents of incoming files, e-mail attachments, active Web content, and so forth to look for virus signatures patterns that match known malware or for possible malicious actions patterns of behavior that are at least suspicious, if not downright unacceptable.
To be more specific, intrusion detection means detecting unauthorized use of or attacks upon a system or network. An IDS is designed and used to detect such attacks or unauthorized use of systems, networks, and related resources, and then in many cases to deflect or deter them if possible. Like firewalls, IDSes can be software-based or can combine hardware and software in the form of preinstalled and preconfigured stand-alone IDS devices.
IDS software may run on the same devices or servers where firewalls, proxies, or other boundary services operate, though separate IDS sensors and managers are more popular. Nevertheless, an IDS not running on the same device or server where the firewall or other services are installed will monitor those devices with particular closeness and care. Although such devices tend to be deployed at network peripheries, IDSes can detect and deal with insider attacks as well as external attacks, and are often very useful in detecting violations of corporate security policy and other internal threats.
You are likely to encounter several kinds of IDSes in the field. First, it is possible to distinguish IDSes by the kinds of activities, traffic, transactions, or systems they monitor.
IDSes that monitor network links and backbones looking for attack signatures are called network-based IDSes, whereas those that operate on hosts and defend and monitor the operating and file systems for signs of intrusion and are called host-based IDSes. A gateway IDS is a network IDS deployed at the gateway between your network and another network, monitoring the traffic passing in and out of your network at the transit point. IDSes that focus on understanding and parsing application-specific traffic with regard to the flow of application logic as well as the underlying protocols are often called application IDSes.
IDSes can also be distinguished by their differing approaches to event analysis. Some IDSes primarily use a technique called signature detection. This resembles the way many antivirus programs use virus signatures to recognize and block infected files, programs, or active Web content from entering a computer system, except that it uses a database of traffic or activity patterns related to known attacks, called attack signatures.
Indeed, signature detection is the most widely used approach in commercial IDS technology today. Another approach is called anomaly detection. It uses rules or predefined concepts about normal and abnormal system activity called heuristics to distinguish anomalies from normal system behavior and to monitor, report, or block anomalies as they occur. Some anomaly detection IDSes implement user profiles. These profiles are baselines of normal activity and can be constructed using statistical sampling, rule-base approaches, or neural networks.
Hundreds of vendors offer various forms of commercial IDS implementations. Most effective solutions combine network- and host-based IDS implementations. Likewise, the majority of implementations are primarily signature-based, with only limited anomaly-based detection capabilities present in certain specific products or solutions.
Finally, most modern IDSes include some limited automatic response capabilities, but these usually concentrate on automated traffic filtering, blocking, or disconnects as a last resort. Although some systems claim to be able to launch counterstrikes against attacks, best practices indicate that automated identification and back-trace facilities are the most useful aspects that such facilities provide and are therefore those most likely to be used.
IDSes are classified by their functionality and are loosely grouped into the following three main categories:. Network-based intrusion detection system NIDS.
Host-based intrusion detection system HIDS. Distributed intrusion detection system DIDS. The NIDS derives its name from the fact that it monitors the entire network from the perspective of the location where it is deployed. More accurately, it monitors an entire network segment. Normally, a computer network interface card NIC operates in nonpromiscuous mode. In promiscuous mode, the NIDS can eavesdrop on all communications on the network segment. In addition, the NIDS should be connected to either a span port on your local switch, or a network tap duplicating traffic on the link you want to monitor.
However, in view of emerging privacy regulations and wiretap laws, monitoring network communications is a responsibility that must be considered carefully. Figure 1. The units have been placed on strategic network segments and can monitor network traffic for all devices on the segment. This configuration represents a standard perimeter security network topology where the screened subnets housing the public servers are protected by NIDS.
When a public server is compromised on a screened subnet, the server can become a launching platform for additional exploits. Careful monitoring is necessary to prevent further damage. The internal host systems are protected by an additional NIDS to mitigate exposure to internal compromise. The use of multiple NIDS within a network is an example of a defense-in-depth security architecture. HIDS protects only the host system on which it resides, and its network card operates by default in nonpromiscuous mode.
Nonpromiscuous mode of operation can be an advantage in some cases, because not all NICs are capable of promiscuous mode. In addition, promiscuous mode can be CPU-intensive for a slow host machine. Due to their location on the host to be monitored, HIDS are privy to all kinds of additional local information with security implications, including system calls, file system modifications, and system logs. In combination with network communications, this provides a robust amount of data to parse through in search of security events of possible concern.
Another advantage of HIDS is the capability to tailor the ruleset very finely for each individual host. For example, there is no need to interrogate multiple rules designed to detect DNS exploits on a host that is not running Domain Name Services. Consequently, the reduction in the number of pertinent rules enhances performance and reduces processor overhead for each host. As previously mentioned, the ruleset for the HIDS on the mail server is customized to protect it from mail server exploits, and the Web server rules are tailored for Web exploits.
During installation, individual host machines can be configured with a common set of rules. New rules can be loaded periodically to account for new vulnerabilities. NIDS detection sensors are remotely located and report to a centralized management station.
Attack logs are periodically uploaded to the management station and can be stored in a central database; new attack signatures can be downloaded to the sensors on an as-needed basis.
The rules for each sensor can be tailored to meet its individual needs. Alerts can be forwarded to a messaging system located on the management station and used to notify the IDS administrator. The network transactions between sensor and manager can be on a private network, as depicted, or the network traffic can use the existing infrastructure.
When using the existing network for management data, the additional security afforded by encryption, or virtual private network VPN technology, is highly recommended. In a DIDS, complexity abounds. The scope and functionality vary greatly from manufacturer to manufacturer, and the definition blurs accordingly.
Snort IDS and IPS Toolkit by Brian Caswell
This all new book covering the brand new Snort version 2. This fully integrated book and Web toolkit covers everything from packet inspection to optimizing Snort for speed to using the most advanced features of Snort to defend even the largest and most congested enterprise networks. Leading Snort experts Brian Caswell, Andrew Baker, and Jay Beale analyze traffic from real attacks to demonstrate the best practices for implementing the most powerful Snort features. The book will begin with a discussion of packet inspection and the progression from intrusion detection to intrusion prevention. The authors provide examples of packet inspection methods including: protocol standards compliance, protocol anomaly detection, application control, and signature matching.
Raffael Marty • Eric Seagren. Snort®. IDS and IPS Toolkit. Featuring Jay Beale and Members of the Snort Team. Andrew R. Baker. Joel Esler. NETWORK.
Snort Intrusion Detection and Prevention Toolkit
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This all new book covering the brand new Snort version 2. This fully integrated book, CD, and Web toolkit covers everything from packet inspection to optimizing Snort for speed to using the most advancedMoreThis all new book covering the brand new Snort version 2. This fully integrated book, CD, and Web toolkit covers everything from packet inspection to optimizing Snort for speed to using the most advanced features of Snort to defend even the largest and most congested enterprise networks. Leading Snort experts Brian Caswell, Andrew Baker, and Jay Beale analyze traffic from real attacks to demonstrate the best practices for implementing the most powerful Snort features. The accompanying CD contains examples from real attacks allowing readers test their new skills.
What Is Intrusion Detection? How an IDS Works. What About Intrusion Protection? Solutions Fast Track. Frequently Asked Questions.