[libvirt] connect: ssh: Shall we remove the dependency of netcat ?

zhang bo oscar.zhangbo at huawei.com
Tue Mar 31 01:02:23 UTC 2015


On 2015/3/28 0:25, Peter Krempa wrote:

> On Fri, Mar 27, 2015 at 10:54:26 +0800, zhang bo wrote:

> 
> Too powerful? That is a ridiculous statement that probably originates
> from some kind of misunderstanding when creating a security policy or
> stuff like that. If a policy bans nc as "powerful" then it's missing on
> a lot of other options how to create listening or outgoing connections
> on arbitrary sockets. The only insecure part is that it does not use
> encryption, but that's a widely known fact about nc.
> 


Sorry for replying so late:)
I tried to confirm the security fact the other days, unfortunately no clear answer gotten.
What I meant was that the *network monitoring tools*, such as 'nc' and 'tcpdump',
they are considered as dangerous for network security. They are prohibited
in our company and some other organizations. I'm not quite sure whether the result that
 they're  prohibited are directly related to their capability of monitoring network.
But they actually got prohibited anyway.

>>
>> 3 So, is there any good substitution for netcat to realize qemu+ssh?
> 
> Currently libvirt doesn't allow this, but I'm planning for a long time
> to introduce a standalone libvirt client binary (or perhaps add this as
> a mode to virsh) to replace the use of NC but that's due to other
> reasons:
> 
> 1) nc doesn't know where session mode sockets are placed
> 
> This is due to the fact that it depends on how libvirt is compiled.
> Currently the client side has to provide the path that is used at the
> remote side and those may not correspond.
> 
> 2) errors reported when using the ssh connection transport are not
> helpful:
> 
> NC is inherently bad at reporting what happened with the unix socket on
> the remote side.
> 
> 3) getting rid of nc as a dependency
> 
> This won't happen though ... old libvirt clients would not be able to
> connect to newer servers.
> 
> 
> In other words. I don't think libvirt will ever get rid of using nc but
> we can make stuff better by adding the internal remote client.
> 
> Peter


Thank you for the detailed reply, glad to hear that it's on schedule to be replaced someday.




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