Annotated edit history of
SysctlNotes version 3 showing authors affecting page license.
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BenStaz |
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!!How to Edit Kernel Parameters During Runtime |
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!List all available kernel parameters and their values: |
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Note : They are all listed under /proc/sys |
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*sysctl -a |
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!Modify the value of a kernel parameter: |
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*sysctl -w variable=value |
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IanMcDonald |
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For example say I do not want my host to respond to pings (note that this is recommended): |
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BenStaz |
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This can be done by telling the kernel to ignore all ICMP ECHO_REQUEST's |
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*sysctl -w net.ipv4.icmp_echo_ignore_all=1 |
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OR |
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*sysctl -w net/ipv4/icmp_echo_ignore_all=1 |
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Notes : |
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1. Setting this variable to 1 (or anything other than 0) will make the kernel ignore ICMP echo request's. |
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2. The 'net.ipv4.icmp_echo_ignore_all' part above specifies the path inside /proc/sys/ to the file corresponding to the kernel parameter. If you use cat to take a look inside this file you will see that all in contains is '1' (the value of the kernel variable) |
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IanMcDonald |
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If you want to save these in a file it's usually in /etc/sysctl.conf (see [sysctl.conf(5)]) |
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JamieCurtis |
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There is also another filesystem full of kernel parameters in called SysFs, normally mounted at /sys. SysFs has more details. |
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IanMcDonald |
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---- |
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CategoryNotes |
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---- |
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JamieCurtis |
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See also [sysctl(8)], [sysctl(2)], SysControls, SysFs |
