[PATCH] Remind user when UserKnownHostsFile is set to /dev/null

[Tong Li]

When UserKnownHostsFile is set to /dev/null in /etc/ssh/ssh_config,
'check_ssh_target()' will return 1 and make 'kdumpctl (re)start' failed.
This patch enables kdumpctl to print information about this issue
to help users locate the problem. But setting UserKnownHostsFile to
'no' (mentioned here https://bugzilla.redhat.com/show_bug.cgi?id=1360131)
isn't under consideration since it seems like that OpenSSH doesn't
support such a method to disable host key checking.

Signed-off-by: Tong Li 
---
 kdumpctl | 8 ++++++++
 1 file changed, 8 insertions(+)

diff --git a/kdumpctl b/kdumpctl
index cb6f004..f0f3ae2 100755
--- a/kdumpctl
+++ b/kdumpctl
@@ -700,6 +700,14 @@ check_ssh_config()
 check_ssh_target()
 {
    local _ret
+	# We need to check host key when dumping to a ssh target, so remind user if UserKnownHostsFile
+	# is set to /dev/null, which is used to disable host key checking.
+	grep -E "^\s*UserKnownHostsFile\s+/dev/null" /etc/ssh/ssh_config &>/dev/null
+	_ret=$?
+	if [ $_ret -eq 0 ]; then
+		echo "Could not check host key, you need to change UserKnownHostsFile in /etc/ssh/ssh_config to a normal file" >&2
+		return 1
+	fi
    ssh -q -i $SSH_KEY_LOCATION -o BatchMode=yes $DUMP_TARGET mkdir -p $SAVE_PATH
    _ret=$?
    if [ $_ret -ne 0 ]; then

[Dave Young]

Hi, Tong

On 12/01/16 at 01:43pm, Tong Li wrote:
> When UserKnownHostsFile is set to /dev/null in /etc/ssh/ssh_config,
> 'check_ssh_target()' will return 1 and make 'kdumpctl (re)start' failed.
> This patch enables kdumpctl to print information about this issue
> to help users locate the problem. But setting UserKnownHostsFile to
> 'no' (mentioned here https://bugzilla.redhat.com/show_bug.cgi?id=1360131)
> isn't under consideration since it seems like that OpenSSH doesn't
> support such a method to disable host key checking.

We force using -o StrictHostKeyChecking=yes in kdump scripts so it
conflicts with our code. It should be corner case we can ignore it to
keep the code simpler.
> Signed-off-by: Tong Li
>
> kdumpctl | 8 ++++++++
>  1 file changed, 8 insertions(+)
>
> diff --git a/kdumpctl b/kdumpctl
> index cb6f004..f0f3ae2 100755
> --- a/kdumpctl
> +++ b/kdumpctl
> @@ -700,6 +700,14 @@ check_ssh_config()
>  check_ssh_target()
>  {
>    local _ret
> # We need to check host key when dumping to a ssh target, so remind user if UserKnownHostsFile
> # is set to /dev/null, which is used to disable host key checking.
> grep -E "^\s*UserKnownHostsFile\s+/dev/null" /etc/ssh/ssh_config &>/dev/null
> _ret=$?
> if [ $_ret -eq 0 ]; then
> echo "Could not check host key, you need to change UserKnownHostsFile in /etc/ssh/ssh_config to a normal file" >&2
> return 1
> fi
> ssh -q -i $SSH_KEY_LOCATION -o BatchMode=yes $DUMP_TARGET mkdir -p $SAVE_PATH
> _ret=$?
> if [ $_ret -ne 0 ]; then
>
> -- 
> 2.7.4
> _______________________________________________
> kexec mailing list -- [e-mail]
> To unsubscribe send an email to [e-mail]

Thanks
Dave