A tty line that is connected to a modem that is used for remote access to the device, or a tty line that is connected to the console port of other devices are also accessible via the network. • Use only the first letter in each word. Network Administration: Hardening Your Network, How to Create a Data Frame from Scratch in R, How to Fill Areas in Minecraft with the Fill Command. The algorithm is not designed to protect configuration files against serious analysis by even slightly sophisticated attackers and must not be used for this purpose. Note: An ATA flash drive has limited disk space and thus needs to be maintained to avoid overwriting stored data. Process switched traffic normally consists of two different types of traffic. Each device that an IP packet traverses decrements this value by one. There are three types of Private VLANs: isolated VLANs, community VLANs, and primary VLANs. MikroTik Security Guide and Networking with MikroTik: MTCNA Study Guide by Tyler Hart are both available in paperback and Kindle! However, SSH must still be enforced as the transport even when IPSec is used. The Hardening Guide adopts standard security and privacy controls and maps them to each of the recommendations. The feature Enhanced Password Security, introduced in Cisco IOS Software Release 12.2(8)T, allows an administrator to configure MD5 hashing of passwords for the username command. Refer to Enhanced Password Security for more information about this feature. This makes it possible to correlate and audit network and security events across network devices more effectively. The link below is a list of all their current guides, this includes guides for Macs, Windows, Cisco, and many others. As, LAN hardening is done to secure whole organization network from attacks. Once IP Options Selective Drop has been enabled, the show ip traffic EXEC command can be used in order to determine the number of packets that are dropped due to the presence of IP options. Added to Cisco IOS Software Release 12.3(14)T, the Exclusive Configuration Change Access feature ensures that only one administrator makes configuration changes to a Cisco IOS device at a given time. This provides an overview of the most important BGP security features. This configuration example illustrates the use of the logging source-interface interface global configuration command in order to specify that the IP address of the loopback 0 interface be used for all log messages: Refer to the Cisco IOS Command Reference for more information. This example describes revocation of a special key. In Cisco IOS Software Release 12.3(4)T and later, you can use the ACL Support for the Filtering IP Options feature in a named, extended IP access list in order to filter IP packets with IP options present. Networking situations exist where security can be aided by limiting communication between devices on a single VLAN. Filtering packets based on TTL values can also be used in order to ensure that the TTL value is not lower than the diameter of the network, thus protecting the control plane of downstream infrastructure devices from TTL expiry attacks. An ARP poisoning attack is a method in which an attacker sends falsified ARP information to a local segment. TACACS+ authentication, or more generally AAA authentication, provides the ability to use individual user accounts for each network administrator. This configuration example limits log messages that are sent to remote syslog servers and the local log buffer to severities 6 (informational) through 0 (emergencies): Refer to Troubleshooting, Fault Management, and Logging for more information. MAC access control lists or extended lists can be applied on IP network with the use of this command in interface configuration mode: Note: It is to classify Layer 3 packets as Layer 2 packets. When the user enters EXEC commands, Cisco IOS sends each command to the configured AAA server. The Cisco Catalyst 6500 Series Supervisor Engine 32 and Supervisor Engine 720 support platform-specific, hardware-based rate limiters (HWRLs) for special networking scenarios. This type of filtering is traditionally performed by firewalls. For example, PVLANs are often used in order to prohibit communication between servers in a publicly accessible subnet. When you consider the security of a network device, it is critical that the management plane be protected. This example includes the configuration of logging timestamps with millisecond precision within the Coordinated Universal Time (UTC) zone: If you prefer not to log times relative to UTC, you can configure a specific local time zone and configure that information to be present in generated log messages. This is accomplished with the, Link Layer Discovery Protocol (LLDP) is an IEEE protocol that is defined in 802.1AB. This traffic contains an entry in the Cisco Express Forwarding (CEF) table whereby the next router hop is the device itself, which is indicated by the term receive in the show ip cef CLI output. The SSHv2 Enhancements for RSA Keys feature also supports RSA-based public key authentication for the client and server. Infrastructure access control lists (iACLs). This example illustrates the configuration of this feature: As BGP packets are received, the TTL value is checked and must be greater than or equal to 255 minus the hop-count specified. You should take steps to protect your network from intruders by configuring the other security features of the network’s servers and routers. A secure protocol choice includes the use of SSH instead of Telnet so that both authentication data and management information are encrypted. Filtering IP packets that are based on the presence of IP options can also be used in order to prevent the control plane of infrastructure devices from having to process these packets at the CPU level. The device that decrements the TTL to zero, and therefore drops the packet, is required in order to generate and send an ICMP Time Exceeded message to the source of the packet. Note: CPPr does not support IPv6 and is restricted to the IPv4 input path. This capability allows you to see what traffic traverses the network in real time. Note that ttys can be used for connections to console ports of other devices. Refer to ACL Support for Filtering on TTL Value for more information about this feature. A typical network operating system can support dozens of different types of network services: file and printer sharing, web server, mail server, and many others. An attacker can be able to exhaust all available memory if it sends a large number of ARP requests. You 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. Refer to key for more information on the configuration and use of Key Chains. Fragmentation is also often used in attempts to evade detection by intrusion detection systems. If you’re responsible for a DoD network, these STIGs (Security Technical Implementation Guides) will help guide your network management, configuration, and monitoring strategies across access control, operating systems, applications, network devices, and even physical security. The Internet Control Message Protocol (ICMP) is designed as an IP control protocol. Any Cisco IOS configuration file that contains encrypted passwords must be treated with the same care that is used for a cleartext list of those same passwords. Man-in-the-middle attacks enable a host on the network to spoof the MAC address of the router, which results in unsuspecting hosts sending traffic to the attacker. Secure network operations is a substantial topic. You are advised to enable this functionality so that the configuration change history of a Cisco IOS device can be more easily understood. After MPP is enabled, no interfaces except designated management interfaces accept network management traffic that is destined to the device. An authorized user who is configured with privilege level 15 cannot be locked out with this feature. It is for these reasons that packets with IP options must be filtered at the edge of the network. You are advised to send logging information to a remote syslog server. Hardening approach. In order to gain knowledge about existing, emerging, and historic events related to security incidents, your organization must have a unified strategy for event logging and correlation. The distribute-list command is available for OSPF, but it does not prevent a router from propagating filtered routes. Mistakes to avoid. Logging timestamps should be configured to include the date and time with millisecond precision and to include the time zone in use on the device. Authentication can be enforced through the use of AAA, which is the recommended method for authenticated access to a device, with the use of the local user database, or by simple password authentication configured directly on the vty or tty line. CDP must be disabled on all interfaces that are connected to untrusted networks. After centralized logging is implemented, you must develop a structured approach to log analysis and incident tracking. Additional information about these communication vehicles is available in the Cisco Security Vulnerability Policy. This is an example configuration for OSPF router authentication using MD5. Hardening guide for Cisco device. Methods used in order to secure access must include the use of AAA, exec-timeout, and modem passwords if a modem is attached to the console. An iACL is constructed and applied in order to specify connections from hosts or networks that need to be allowed to network devices. All transit traffic that crosses the network and is not destined to infrastructure devices is then explicitly permitted. Cisco IOS devices have a limited number of vty lines; the number of lines available can be determined with the show line EXEC command. ICMP unreachable rate limiting can be changed from the default with the global configuration command ip icmp rate-limit unreachable interval-in-ms. Proxy ARP is the technique in which one device, usually a router, answers ARP requests that are intended for another device. This configuration example illustrates the use of this command: ICMP redirects are used in order to inform a network device of a better path to an IP destination. If these protocols are in use in the network, then the ACL Support for Filtering IP Options can be used; however, the ACL IP Options Selective Drop feature could drop this traffic and these protocols might not function properly. This configuration example configures VLAN 11 as an isolated VLAN and associates it to the primary VLAN, VLAN 20. During configuration of the ip verify interface configuration command, the keyword any configures loose mode while the keyword rx configures strict mode. 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