Block third-party DHCP servers on the Huawei Quidway S2300

I will give an example of how on the Huawei Quidway S2300 switch (using the S2326TP-EI as an example) to allow receiving DHCP responses from the uplink port and prohibiting client responses. First, enable dhcp snooping: Let’s enable dhcp snooping in the client vlan: And allow DHCP responses from the incoming uplink port: After that, […]

Installing and configuring isc-dhcp-server in Ubuntu

Here’s an example of installing isc-dhcp-server in Ubuntu Server. Installation command: Open the first configuration file: Specify the name of the interface from which the IP addresses will be sent (for example, eth0): Suppose that this interface has a static address in /etc/network/interfaces: Let’s make a backup copy of the second configuration file: Create a […]

Installing and Using dhcpdump

dhcpdump – sniffer utility for analyzing DHCP packets. I will give an example of the installation command in Ubuntu/Debian: Installation in CentOS: Let’s see what network interfaces are in the system: Example of running dhcpdump with the name of the network interface: An example of intercepting DHCP packets with only the specified MAC address ending: […]

How to fix error “dhcpd self-test failed. Please fix the config file”

I noticed once in the syslog: dhcpd self-test failed. Please fix the config file Isc-dhcp-server was installed on the server. To check the correctness of the configuration file, use the command: The command should tell which line the error is, but noted that if it is not critical, it may not. The key “t” executes […]