Linux Firewall-related /proc Entries
There are many settings inside the Linux kernel that can vary from machine to machine. Traditionally, these were set at compile time, or sometimes were modifiable through oft-esoteric system calls. For example each machine has a host name which would be set at boot time using the sethostname(2) system call, while iptables reads and modifies your Netfilter rules using getsockopt(2) and setsockopt(2), respectively.
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