Re: [PATCH]: Add Network Sysrq Support
From: Randy Dunlap <hidden>
Date: 2011-06-21 20:09:32
On Tue, 21 Jun 2011 09:00:40 -0400 Prarit Bhargava wrote:
Add Network Sysrq Support
quoted hunk ↗ jump to hunk
Signed-off-by: Prarit Bhargava <redacted>diff --git a/Documentation/networking/sysrq-ping.txt b/Documentation/networking/sysrq-ping.txt new file mode 100644 index 0000000..efa8be3 --- /dev/null +++ b/Documentation/networking/sysrq-ping.txt@@ -0,0 +1,26 @@ +In some circumstances, a system can hang/lockup in such a way that the system +is completely unresponsive to keyboard or console input but is still +responsive to ping. The config option, CONFIG_SYSRQ_PING, builds +net/ipv4/sysrq-ping.ko which allows a root user to configure the system for a
or it can be built-in the kernel image... (i.e., not a loadable module)
+remote sysrq. + +To use this do: + +mount -t debugfs none /sys/kernel/debug/ +echo 1 > /proc/sys/kernel/sysrq +echo <hex digit val> > /sys/kernel/debug/network_sysrq_magic +echo 1 > /sys/kernel/debug/network_sysrq_enable
so all of this (insecure) stuff has to be done before you suspect that you need it .. in case the local keyboard/console is dead.
+ +Then on another system you can do: + +ping -c 1 -p <hex digit val><hex val of sysrq> <target_system_name>
What are the <up to 30 hex digits> for?
+ +ex) sysrq-m, m is ascii 0x6d
e.g., sysrq-m (m is ASCII 0x6d)
+ + ping -c 1 p 1623a06f554d46d676d <target_system_name> + +Note that the network sysrq automatically disables after the receipt of +the ping, ie) it is single-shot mode. If you want to use this again, you
i.e., it is single-shot mode.
quoted hunk ↗ jump to hunk
+must complete the above four steps again. + +Hint: 'man ascii' ;)diff --git a/net/ipv4/Kconfig b/net/ipv4/Kconfig index cbb505b..03bb7b1 100644 --- a/net/ipv4/Kconfig +++ b/net/ipv4/Kconfig@@ -624,3 +624,11 @@ config TCP_MD5SIG on the Internet. If unsure, say N. + +config SYSRQ_PING + tristate
Needs a prompt?
+ default m
Please do not enable random code to be built.
+ help + Allows execution of sysrq-X commands via ping over ipv4. This is a
No ipv6 support? future?
+ known security hazard and should not be used in unsecure
insecure
+ environments.
--- ~Randy *** Remember to use Documentation/SubmitChecklist when testing your code ***