Overview: Basic device hardening consists of setting user authentication passwords, enable passwords, restricting access to the device through telnet/SSH and displaying login banners. Study Notes: Device hardening helps to restrict access to different command modes on routers and switches Command Mode Access Method Prompt Exit Method User EXEC Log in Router> Use the logout […]
Overview: Access-lists are used to permit and deny different traffic based on the filtering criteria specified in the list Study Notes: Access-lists are evaluated top down from first entry to last entry Once the traffic matches an entry in the list an action is taken – permit or deny Therefore, put more specific entries […]
Overview: Port security can be used on an interface to identify and limit the MAC addresses of clients that are allowed to access that port. Study Notes: Port security identifies the MAC addresses of clients allowed to forward traffic through an interface Port security is applied to access ports Port security cannot be applied […]
Overview: The Network Time Protocol (NTP) synchronizes the time of day among a set of distributed time servers and clients Study Notes: NTP synchronizes time across devices so you can correlate system logs and other time-specific events from multiple network devices NTP uses UDP as its transport protocol An NTP server normally receives its time […]
Overview: Inside source Network Address Translation (NAT) is used to map private IP addresses on a LAN to a public IP address(es) on the outside interface of the router Study Notes: Inside source Network Address Translation (NAT) is used to map private IP addresses on a LAN to public IP address(es) on the outside […]
Overview: Hot Standby Routing Protocol (HSRP) enables high availability by providing multiple default gateways with the same virtual IP address to hosts on a LAN. Study Notes: HSRP is a Cisco proprietary protocol HSRP routes IP traffic without relying on the availability of any single router on the LAN Multiple router interfaces work together […]
Overview: Client and router based DHCP connectivity issues can be the result of any number of issues, but most often it is due to a misconfiguration. Study Notes: Client and router based DHCP connectivity issues are typically the result of misconfigurations. Has the DHCP lease expired? If the lease has expired and another client […]
Overview: Dynamic Host Control Protocol (DHCP) provides configuration parameters to hosts. Study Notes: The DHCP protocol configures hosts with network settings The DHCP protocol provides other configurable parameters including conflict logging – conflicts occur when 2 hosts use the same IP address excluded addresses – range of IPs to exclude from the DHCP pool […]
Overview: The Cisco IOS DHCP feature can be configured with a few optional, but recommended, commands including TFTP, DNS and Default Gateway. Study Notes: The Cisco IOS DHCP feature can be configured with a few optional, but recommended, commands including TFTP, DNS and Default Gateway IP address. The TFTP option 150 is used to […]
Overview: The Cisco IOS DHCP client enables a device to obtain an IP address from a DHCP Server dynamically using the DHCP protocol. Study Notes: The Cisco IOS DHCP client enables a device to obtain an IP address from a DHCP Server dynamically using the DHCP protocol as specified in RFC 2131. In Cisco […]