After being deprecated for several years, Security Enhanced Linux "SELinux" beginning with the Linux 6.4 kernel can no longer be run-time disabled. . For a while now SELinux deprecated run-time disabling for turning off SELinux via its config file or sysfs. By getting rid of the run-time disabling support, SELinux developers can make various improvements currently blocked by this code. Those wishing to disable SELinux support can still do so via the selinux=0 boot time option or when building the Linux kernel toggling the "CONFIG_SECURITY_SELINUX_DISABLE" Kconfig switch. The SELinux run-time disabling removal is made as part of this pull request pending for the newly-opened Linux 6.4 merge window. The link for this article located at Phoronix is no longer available. . The removal of run-time disabling for SELinux in Linux 6.4 impacts security protocols significantly, requiring admins to adapt their strategies for compliance.. SELinux Enhancements, Linux Kernel Changes, Security Features, Runtime Support. . LinuxSecurity.com Team
A change queued up as part of the "x86/mm" TIP changes expected to land for Linux 6.1 will now have the default kernel configuration warn at kernel boot time around any W+X mappings that pose a security risk. . Going back to 2015 has been the "CONFIG_DEBUG_WX" kernel option to warn of mappings at kernel boot time that are set to writable and executable, since they pose a security risk. The intention of this "debug" option is to warn of W+X mappings left by the kernel after applying NX. Any mappings will be dumped to the kernel log for uncovering potential kernel problems. CONFIG_DEBUG_WX has been happily working on Linux kernel releases for the past seven years albeit not part of the x86/x86_64 default kernel configuration. But with this week's TIP x86/mm changes of material queuing ahead of the Linux 6.1 merge window, CONFIG_DEBUG_WX would be enabled by default. The link for this article located at Phoronix is no longer available. . The latest iteration of the Linux 6.1 kernel introduces notifications for W+X memory mappings during initialization, bolstering security protocols against potential threats.. Linux Kernel, Boot Security, Code Execution Risk. . LinuxSecurity.com Team
Most people, when creating a Linux firewall, concentrate soley on manipulating kernel network filters: the rulesets you create using userspace tools such as iptables (2.4 kernels,) ipchains (2.2 kernels,) or even ipfwadm (2.0 kernels). However there are kernel variables -- . . . . Most people, when creating a Linux firewall, concentrate soley on manipulating kernel network filters: the rulesets you create using userspace tools such as iptables (2.4 kernels,) ipchains (2.2 kernels,) or even ipfwadm (2.0 kernels). However there are kernel variables -- independent of any kernel filtering rules -- that affect how the kernel handles network packets. This article will discuss these variables and the effect they have on the network security of your Linux host or firewall. 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. The link for this article located at SecurityFocus is no longer available. . Enhance the Linux firewall's security and performance by adjusting key kernel network settings like IP forwarding and connection tracking configurations. Firewall Security, Kernel Configuration, Network Security, Linux Performance. . Anthony Pell
As of 2.4, ipchains is a thing of the past. The replacement for ipchains is Netfilter's iptables. What does this mean to the end user? Typically it means little beyond the fact that suddenly their ipmasq script doesn't work. So, for . . . . As of 2.4, ipchains is a thing of the past. The replacement for ipchains is Netfilter's iptables. What does this mean to the end user? Typically it means little beyond the fact that suddenly their ipmasq script doesn't work. So, for starters let's get into setting up ipmasq under 2.4.x kernels. Connection tracking is a new feature of netfilter that allows you to accept or deny a packet based on the state of the connection rather than the strict allow/deny of ipchains. NAT of course stands for Network Address Translation, the key feature behind IP Masquerade. The other entries in this menu are optional, enable them as you please and recompile the kernel if needed. The link for this article located at Linux.com is no longer available. . Explore how Netfilter's iptables improved IP masquerading in Linux kernel 2.4, providing better packet filtering and NAT capabilities.. IP Masquerade, Netfilter, Iptables, Kernel Configuration. . Anthony Pell
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