Firewall Guide For Mac

Posted : admin On 09.11.2019
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Findings (MAC I - Mission Critical Classified) Finding ID Severity Title Description High The firewall must employ filters that prevent or limit the effects of all types of commonly known denial-of-service (DoS) attacks, including flooding, packet sweeps, and unauthorized port scanning. Not configuring a key boundary security protection device such as the firewall against commonly known attacks is an immediate threat to the protected enclave because they are easily implemented. High The firewall must be configured to use filters that prevent or limit the effects of all types of commonly known denial-of-service (DoS) attacks, including flooding, packet sweeps, and unauthorized port scanning. To prevent malicious or accidental leakage of traffic, organizations must implement a deny-by-default security posture at the network perimeter.

Such rulesets prevent many malicious exploits. High The firewall must be configured to use filters that use packet headers and packet attributes, including source and destination IP addresses and ports, to prevent the flow of unauthorized or suspicious traffic between interconnected networks with different security policies (including perimeter firewalls and server VLANs).

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Information flow control regulates where information is allowed to travel within a network and between interconnected networks. Blocking or restricting detected harmful or suspicious. Medium The firewall must generate traffic log entries containing information to establish the outcome of the events, such as, at a minimum, the success or failure of the application of the firewall rule. Without information about the outcome of events, security personnel cannot make an accurate assessment as to whether an attack was successful or if changes were made to the security state of the. Medium If communication with the central audit server is lost, the firewall must generate a real-time alert to, at a minimum, the SCA and ISSO. Without a real-time alert (less than a second), security personnel may be unaware of an impending failure of the audit functions and system operation may be adversely impacted. Alerts provide.

Medium The firewall must be configured to send traffic log entries to a central audit server for management and configuration of the traffic log entries. Without the ability to centrally manage the content captured in the traffic log entries, identification, troubleshooting, and correlation of suspicious behavior would be difficult and could lead.

Medium The firewall must be configured to send a real-time alert to the ISSO and SA (at a minimum) in the event of an audit processing failure on the firewall itself. It is critical for the appropriate personnel to be aware if a system is at risk of failing to process traffic logs as required.

Without this notification, the security personnel may be unaware of. Medium The firewall that filters traffic from the wireless access points must be configured with organization-defined filtering rules that apply to the monitoring of remote access traffic. Remote access devices (such as those providing remote access to network devices and information systems) that lack automated capabilities increase risk and make remote user access management. Medium The firewall must immediately use updates made to policy enforcement mechanisms such as firewall rules, security policies, and security zones.

Information flow policies regarding dynamic information flow control include, for example, allowing or disallowing information flows based on changes to the Ports, Protocols, Services Management. Medium The firewall implementation must manage excess bandwidth to limit the effects of packet flooding types of denial-of-service (DoS) attacks.

A firewall experiencing a DoS attack will not be able to handle production traffic load. The high utilization and CPU caused by a DoS attack will also have an effect on control keep-alives. Medium The firewall that filters traffic from the VPN access points must be configured with organization-defined filtering rules that apply to the monitoring of remote access traffic. Remote access devices (such as those providing remote access to network devices and information systems) that lack automated capabilities increase risk and make remote user access management. Medium The firewall must disable or remove unnecessary network services and functions that are not used as part of its role in the architecture.

Network devices are capable of providing a wide variety of functions (capabilities or processes) and services. Some of these functions and services are installed and enabled by default. Medium The firewall must fail to a secure state if the firewall filtering functions fail unexpectedly. Firewalls that fail suddenly and with no incorporated failure state planning may leave the hosting system available but with a reduced security protection.

Failure to a known safe state helps. Medium The firewall must generate traffic log records when attempts are made to send packets between security zones that are not authorized to communicate. Without generating log records that are specific to the security and mission needs of the organization, it would be difficult to establish, correlate, and investigate the events relating to an. Medium In the event of a system failure of the firewall function, the firewall must be configured to save diagnostic information, log system messages, and load the most current security policies, rules, and signatures when restarted.

Failure to a secure state can address safety or security in accordance with the mission needs of the organization. Failure to a secure state helps prevent a loss of confidentiality, integrity,. Medium The perimeter firewall must be configured for service redundancy, load balancing, or other organization-defined safeguards to limit the effects of types of denial-of-service (DoS) attacks on the network. As a critical security system, perimeter firewalls must be safeguarded with redundancy measures. If the network does not provide safeguards against DoS attacks, network resources will be. Medium The firewall must generate traffic log records when traffic is denied, restricted, or discarded.

Without generating log records that log usage of objects by subjects and other objects, it would be difficult to establish, correlate, and investigate the events relating to an incident. Medium The firewall must generate traffic log entries containing information to establish the location on the network where the events occurred. Without establishing where events occurred, it is impossible to establish, correlate, and investigate the events leading up to an outage or attack. In order to compile an accurate risk assessment. Medium The firewall must protect traffic log records from unauthorized read access while stored locally. Auditing and logging are key components of any security architecture.

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Logging the actions of specific events provides a means to investigate an attack, recognize resource utilization or capacity. Medium The firewall must protect the traffic log from unauthorized modification of local log records. If audit data were to become compromised, forensic analysis and discovery of the true source of potentially malicious system activity would be impossible to achieve. To ensure the veracity of. Medium In the event that communication with the central audit server is lost, the firewall must continue to queue traffic log records locally. It is critical that when the network element is at risk of failing to process traffic logs as required, it takes action to mitigate the failure.

Mac

Audit processing failures include software/hardware. Medium The firewall must protect traffic log records from unauthorized access while in transit to the central audit server. Auditing and logging are key components of any security architecture.

Logging the actions of specific events provides a means to investigate an attack, recognize resource utilization or capacity. Medium The firewall must protect the traffic log from unauthorized deletion of local log files and log records. If audit data were to become compromised, forensic analysis and discovery of the true source of potentially malicious system activity would be impossible to achieve. To ensure the veracity of.

Medium The firewall must generate traffic log entries containing information to establish when (date and time) the events occurred. Without establishing when events occurred, it is impossible to establish, correlate, and investigate the events leading up to an outage or attack. In order to compile an accurate risk assessment. Medium The firewall must generate traffic log entries containing information to establish what type of events occurred.

Without establishing what type of event occurred, it would be difficult to establish, correlate, and investigate the events leading up to an outage or attack. Audit event content that may be. Medium The firewall must be configured to prohibit or restrict the use of functions, ports, protocols, and/or services on the network segment in accordance as defined in the Ports, Protocols, and Services Management (PPSM) CAL and vulnerability assessments.

Some ports, protocols, or services have well-known exploits or security weaknesses that can be leveraged in an attack against the enclave and put it at immediate risk. These ports, protocols,. Medium The firewall must establish ingress filters that block inbound packets where the destination is an IP address assigned to the management or loopback addresses of the enclave protection devices unless the packet has a source address assigned to the management network or network infrastructure. The firewall must reject requests for access or services where the source address received by the firewall specifies a loopback address. The loopback address is used by an Inter-Processor Control. Medium The firewall must apply egress filters to traffic that is outbound from the network through any internal interface.

If outbound communications traffic is not filtered, hostile activity intended to harm other networks or packets from networks destined to unauthorized networks may not be detected and prevented. Medium The premise firewall (located behind the premise router) must block all outbound management traffic. The management network must still have its own subnet in order to enforce control and access boundaries provided by Layer 3 network nodes such as routers and firewalls. Management traffic between.

Medium The firewall must block or restrict inbound IP packets destined to the control plane of the firewall itself. As a critical security system, perimeter firewalls must be safeguarded against direct attacks to the device. The firewall must have a filter that rejects requests for access or services where the. Medium The firewall must fail closed if the firewall filtering function is nonfunctional. While failure to an open state may ensure users are not inconvenienced, it also circumvents a critical security network function that guards against direct and indirect network attacks. Medium The firewall must apply ingress filters to traffic that is inbound to the network through any active external interface.

Unrestricted traffic to the trusted networks may contain malicious traffic that poses a threat to an enclave or to other connected networks. Additionally, unrestricted traffic may transit a. Medium The firewall must restrict traffic entering the VPN tunnels to the management network to only the authorized management packets based on destination address. Protect the management network with a filtering firewall configured to block unauthorized traffic.

This requirement is similar to the out-of-band management (OOBM) model, when the production. Medium The perimeter firewall must filter traffic destined to the internal enclave in accordance with the specific traffic that is approved and registered in the Ports, Protocols, and Services Management (PPSM) Category Assurance List (CAL), Vulnerability Assessments (VAs) for that the enclave. The enclave's internal network contains the servers where mission-critical data and applications reside. Malicious traffic can enter from an external boundary or originate from a compromised host. Medium The firewall must be configured to fail securely in the event of an operational failure of the firewall filtering or boundary protection function. If a boundary protection device fails in an unsecure manner (open), information external to the boundary protection device may enter, or the device may permit unauthorized information. Medium The firewall must block outbound IP packets that contain illegitimate packet attributes including, at a minimum, invalid source address or packets that fail minimum length tests (TCP length, UDP length, IP data length) that have undefined protocol numbers, improper use of hop-by-hop header, or IPv6 RH0 header.

If outbound communications traffic is not filtered, hostile activity intended to harm other networks may not be detected and prevented. Medium The firewall must be configured to allow authorized users to record a packet capture based IP, traffic type (TCP, UDP, or ICMP), or protocol. Without the ability to capture, record, and log content related to a user session, investigations into suspicious user activity would be hampered. This configuration ensures the ability to select. Medium The firewall must block outbound traffic containing denial-of-service (DoS) attacks to protect against the use of internal information systems to launch any DoS attacks against other networks or endpoints. DoS attacks can take multiple forms but have the common objective of overloading or blocking a network or host to deny or seriously degrade performance.

If the network does not provide safeguards. Low The firewall must generate traffic log entries containing information to establish the source of the events, such as the source IP address at a minimum. Without establishing the source of the event, it is impossible to establish, correlate, and investigate the events leading up to an outage or attack. In order to compile an accurate risk. Low The firewall must be configured to allow the system administrator to select a subset of DoD-required auditable events. The generation of logs with a subset of criteria aide the system administrator, maintainers, and auditors when troubleshooting issues or reviewing the log for trends or security breaches. Low The firewall must generate an alert that can be forwarded to, at a minimum, the ISSO and ISSM when denial-of-service (DoS) incidents are detected.

Without an alert, security personnel may be unaware of major detection incidents that require immediate action, and this delay may result in the loss or compromise of information. The firewall.

About iptables iptables is a command-line firewall utility that uses policy chains to allow or block traffic. When a connection tries to establish itself on your system, iptables looks for a rule in its list to match it to. If it doesn’t find one, it resorts to the default action. Iptables almost always comes pre-installed on any Linux distribution. To update/install it, just retrieve the iptables package: sudo apt-get install iptables There are GUI alternatives to iptables like, but iptables isn’t really that hard once you have a few commands down. You want to be extremely careful when configuring iptables rules, particularly if you’re SSH’d into a server, because one wrong command can permanently lock you out until it’s manually fixed at the physical machine. Types of Chains iptables uses three different chains: input, forward, and output.

Input – This chain is used to control the behavior for incoming connections. For example, if a user attempts to SSH into your PC/server, iptables will attempt to match the IP address and port to a rule in the input chain. Forward – This chain is used for incoming connections that aren’t actually being delivered locally. Think of a router – data is always being sent to it but rarely actually destined for the router itself; the data is just forwarded to its target. Unless you’re doing some kind of routing, NATing, or something else on your system that requires forwarding, you won’t even use this chain. There’s one sure-fire way to check whether or not your system uses/needs the forward chain. Iptables -L -v The screenshot above is of a server that’s been running for a few weeks and has no restrictions on incoming or outgoing connections.

As you can see, the input chain has processed 11GB of packets and the output chain has processed 17GB. The forward chain, on the other hand, has not needed to process a single packet. This is because the server isn’t doing any kind of forwarding or being used as a pass-through device. Output – This chain is used for outgoing connections.

For example, if you try to ping howtogeek.com, iptables will check its output chain to see what the rules are regarding ping and howtogeek.com before making a decision to allow or deny the connection attempt. The caveat Even though pinging an external host seems like something that would only need to traverse the output chain, keep in mind that to return the data, the input chain will be used as well.

When using iptables to lock down your system, remember that a lot of protocols will require two-way communication, so both the input and output chains will need to be configured properly. SSH is a common protocol that people forget to allow on both chains. Policy Chain Default Behavior Before going in and configuring specific rules, you’ll want to decide what you want the default behavior of the three chains to be. In other words, what do you want iptables to do if the connection doesn’t match any existing rules? To see what your policy chains are currently configured to do with unmatched traffic, run the iptables -L command.

As you can see, we also used the grep command to give us cleaner output. In that screenshot, our chains are currently figured to accept traffic. More times than not, you’ll want your system to accept connections by default. Unless you’ve changed the policy chain rules previously, this setting should already be configured.

Either way, here’s the command to accept connections by default: iptables -policy INPUT ACCEPT iptables -policy OUTPUT ACCEPT iptables -policy FORWARD ACCEPT By defaulting to the accept rule, you can then use iptables to deny specific IP addresses or port numbers, while continuing to accept all other connections. We’ll get to those commands in a minute. If you would rather deny all connections and manually specify which ones you want to allow to connect, you should change the default policy of your chains to drop.

Doing this would probably only be useful for servers that contain sensitive information and only ever have the same IP addresses connect to them. Iptables -policy INPUT DROP iptables -policy OUTPUT DROP iptables -policy FORWARD DROP Connection-specific Responses With your default chain policies configured, you can start adding rules to iptables so it knows what to do when it encounters a connection from or to a particular IP address or port. In this guide, we’re going to go over the three most basic and commonly used “responses”. Accept – Allow the connection. Drop – Drop the connection, act like it never happened.

This is best if you don’t want the source to realize your system exists. Reject – Don’t allow the connection, but send back an error. This is best if you don’t want a particular source to connect to your system, but you want them to know that your firewall blocked them. The best way to show the difference between these three rules is to show what it looks like when a PC tries to ping a Linux machine with iptables configured for each one of these settings.

Allowing the connection: Dropping the connection: Rejecting the connection: Allowing or Blocking Specific Connections With your policy chains configured, you can now configure iptables to allow or block specific addresses, address ranges, and ports. In these examples, we’ll set the connections to DROP, but you can switch them to ACCEPT or REJECT, depending on your needs and how you configured your policy chains. Note: In these examples, we’re going to use iptables -A to append rules to the existing chain. Iptables starts at the top of its list and goes through each rule until it finds one that it matches. If you need to insert a rule above another, you can use iptables -I chain number to specify the number it should be in the list. Connections from a single IP address This example shows how to block all connections from the IP address 10.10.10.10.

Iptables -A INPUT -s 10.10.10.10 -j DROP Connections from a range of IP addresses This example shows how to block all of the IP addresses in the 10.10.10.0/24 network range. You can use a netmask or standard slash notation to specify the range of IP addresses. Iptables -A INPUT -s 10.10.10.0/24 -j DROP or iptables -A INPUT -s 10.10.10.0/255.255.255.0 -j DROP Connections to a specific port This example shows how to block SSH connections from 10.10.10.10. Iptables -A INPUT -p tcp -dport ssh -s 10.10.10.10 -j DROP You can replace “ssh” with any protocol or port number. The -p tcp part of the code tells iptables what kind of connection the protocol uses. If you were blocking a protocol that uses UDP rather than TCP, then -p udp would be necessary instead.

This example shows how to block SSH connections from any IP address. Iptables -A INPUT -p tcp -dport ssh -j DROP Connection States As we mentioned earlier, a lot of protocols are going to require two-way communication. For example, if you want to allow SSH connections to your system, the input and output chains are going to need a rule added to them. But, what if you only want SSH coming into your system to be allowed? Won’t adding a rule to the output chain also allow outgoing SSH attempts?

That’s where connection states come in, which give you the capability you’d need to allow two way communication but only allow one way connections to be established. Take a look at this example, where SSH connections FROM 10.10.10.10 are permitted, but SSH connections TO 10.10.10.10 are not. However, the system is permitted to send back information over SSH as long as the session has already been established, which makes SSH communication possible between these two hosts. Iptables -A INPUT -p tcp -dport ssh -s 10.10.10.10 -m state -state NEW,ESTABLISHED -j ACCEPT iptables -A OUTPUT -p tcp -sport 22 -d 10.10.10.10 -m state -state ESTABLISHED -j ACCEPT Saving Changes The changes that you make to your iptables rules will be scrapped the next time that the iptables service gets restarted unless you execute a command to save the changes.

This command can differ depending on your distribution: Ubuntu: sudo /sbin/iptables-save Red Hat / CentOS: /sbin/service iptables save Or /etc/init.d/iptables save Other Commands List the currently configured iptables rules: iptables -L Adding the -v option will give you packet and byte information, and adding -n will list everything numerically. In other words – hostnames, protocols, and networks are listed as numbers. To clear all the currently configured rules, you can issue the flush command.