Category: networking

quantum computing and a universe wide wireless communication network faster than the speed of light

Why is quantum computing important: optimization Update: Google claims to have reached quantum supremacy The tech giant unveiled its x-quantum computer chip Bristlecone in March 2018 (src: cnet) original nasa paper: book: Scott’s Supreme Quantum Supremacy FAQ! […]

ntpd – when fundamentals fail

servers/clients/computers/programs/services/webservers need accurate time… they usually get it from time servers that have an atomic clock attached to their USB port. (just guessing) ping PING ( 56(84) bytes of data. 64 bytes from ( icmp_seq=1 ttl=46 time=43.5 […]

a pretty good ipv6 introduction – ipv4 depletion

IPv6: Introduction it’s the year 2019, roughly 14% of the web is running ipv6. you can watch real time statistics here: (i have no clue how accurate the data is, how they are generated) … but it seems there […]

lnav – like less but more colorful output of log files

CentOS8: ccze author not willing to maintain ccze. no ccze and not even lnav available. how to monitor all logs… as i was wondering what combination of less -R with or without ccze would allow me to view log […]

Monitoring Performance of Linux Servers

monitor (andoird) devices with bpf: so guess “monitoring” is about two things: availability and performance: detect performance bottlenecks get informed if parts (harddisks) / servers have failed / are about to fail security: detect, report and (if possible) automatically […]


tested on: hostnamectl Static hostname: DebianLaptop Icon name: computer-laptop Chassis: laptop Operating System: Debian GNU/Linux 8 (jessie) Kernel: Linux 3.16.0-4-686-pae Architecture: x86 i assume you have your laptop/pc LAN connected to a switch/router and your default network card is eth0. […]


per default debian is not configured to forward traffic. on server/router/gateway: ping; # make sure internet connection works ifconfig eth0:0 netmask up; # add additional ip vim /etc/sysctl.conf # Uncomment the next line to enable packet forwarding […]


what service/program is using what port: IPTraf, Iftop, vnstat, bwm-ng, ifconfig -a graphical: gives you overall statistics the blue stuff on the left: iptraf manpage: you probably want to let it run in a screen session, in order […]


show the ARP cache every network interface card (NIC)/LAN network card has a unique-as-possible vendor-asigned MAC address in the format 00:15:5d:00:07:08 this address is changeable like this: ip link set dev eth0 down; ip link set dev eth0 address 00:15:5d:00:07:09; […]

IPv4 CIDR Subnet Mask Notation

IPv4 CIDR Subnet Mask Notation The CIDR number comes from the number of 1’s in the subnet mask when converted to binary. The common subnet mask is 11111111.11111111.11111111.00000000 in binary. This adds up to 24 1’s, or /24 (pronounced […]