Linux
Xtables-addons: GeoIP, TARPIT and the psd Module I Ported
Extra iptables matches and targets the kernel never shipped: country blocking with geoip, a TARPIT decoy port, port knocking, and the psd scan detector I ported.
Topic
networking
MySQL
Store IPv4 and IPv6 Together in MySQL With INET6_ATON()
One column for both address families: INET6_ATON() and INET6_NTOA(), IPv4-mapped addresses, correct sorting, indexed range queries and MariaDB's native INET6 type.
MySQL
Match an IPv4 Address Against a CIDR Subnet in MySQL
Store IPv4 addresses as INT UNSIGNED and test CIDR membership with a bitmask or, much faster on a big table, an indexed BETWEEN range on network and broadcast.
Linux
Find Which Process Is Listening on a Port in Linux
"Address already in use" again? How to find the owner of a port with ss, lsof and fuser, decode /proc/net/tcp by hand, and why some ports show no process.
MySQL
ipcalc() in MySQL: Network, Broadcast and Prefix From a Netmask
Work out the network, broadcast address and prefix length of an IPv4 address inside a query, using INET_ATON(), INET_NTOA() and a little bitwise arithmetic.