[et-mgmt-tools] An advantage to add VNC-Port setting when virt-manager creates VM
fj0588di at aa.jp.fujitsu.com
Thu Jun 14 05:23:03 UTC 2007
I compile my opinion simply.
- Same as virt-install,
I want to give a user the right that can select auto or fix in virt-manager.
- At first, the authentication has nothing to do with a function that fix port number.
> it would be desirable to only open up a port when explicitly needed,
> and not require the admin to do any work.
I think so too.
but, as follows,
I think that need to fix a port necessarily comes out.
When I have already used 5900-5920 about a port number
(Use except vnc or use in vnc except virt-manager),
Need to review a system using 5900 for comes out,
when I install a guest with auto selection newly.
With it, a review of the whole system may occur.
In the case of an example,
a manager will assign it to a new guest anything other than 5900-5920.
Because a user can do operation & management that include setting of a port with virt-install,
I think that we should give a user the right to be able to do operation & management with virt-manager.
After having stood on these,
Which thinks it to be big with an advantage when there is a function of fixed port selection
and an advantage when there is not it?
<200706081441.GID09350.90EGJK69 at aa.jp.fujitsu.com> の、
"Re: [et-mgmt-tools] [PATCH] Add VNC-Port settingwhenvirt-managercreates VM" において、
""S.Sakamoto" <fj0588di at aa.jp.fujitsu.com>"さんは書きました：
> Hi, Dan
> Would you give me a comment?
> --- The summary of last time ---
> The user who wants to manage GUEST from port number 9000 does not use the virt-manager
> if it cannot choose a port at the time of use when he introduce GUEST.
> Even if the virt-manager is no matter how convenient,
> this user will avoid use of the virt-manager because it forces him to allocate from 5600- .
> How do you think about this problem?
> I think that this user is not niche!
> Shigeki Sakamoto.
> <200705311822.JEJ86930.0JK9G96E at aa.jp.fujitsu.com> の、
> "Re: [et-mgmt-tools] [PATCH] Add VNC-Port setting whenvirt-managercreates VM" において、
> ""S.Sakamoto" <fj0588di at aa.jp.fujitsu.com>"さんは書きました：
> > Hi
> > An advantage of the fixed port which I want to insist on is "A user can choose an arbitrary port.".
> > Neither remote-connection nor authentication matters particularly. It is a story before it.
> > The reason why this user comes to need choice of a fixed port is as follows.
> > If an user absolutely use the port number from 5900, either does not surely matter.
> > But,
> > for example,
> > when the port number 5900-5920 is used by other uses,
> > when there is a user hoping that I manage a port number by use to assign from 9000,
> > A fxed port selection mode is necessary, because there is these situation.
> > (The person who does not need a fixed port should choose an auto selection mode.)
> > Any users will not hope to change other designs to use it for auto selection.
> > Thanks,
> > Shigeki Sakamoto.
> > > On Tue, May 29, 2007 at 04:44:15PM +0900, S.Sakamoto wrote:
> > > > Hi, Dan
> > > >
> > > > Thanks for your comment.
> > > >
> > > > > It will prove unreliable in practice, because even if you
> > > > > fix a particular guest on port 5905, any other guest doing dynamic VNC port
> > > > > assignment may choose this port before the hardcoded guest starts.
> > > > This situation is surely thought.
> > > > But, I think that problem is solved
> > > > if it performs a repetition check of a port number in virt-inst.
> > > > When it is this situation, at first,
> > > > examine the port number that all other guests use when it starts a guest.
> > > > Next, If the port number is fixed and repetition,
> > > > output a message. [e.g."Repetition. Set a different port number."]
> > > > (However, there is not a function setting a port for an existing guest now.
> > > > If it is necessary at the same time,
> > > > I make 'check of repetition' and 'function setting a port for an existing guest'.)
> > > >
> > > > > It is not going to be easy for virt-manager to do validation of this port number
> > > > > either, since in the near future virt-manager may well be running remotely
> > > > > from the host.
> > > > If it adds a revision to libvirt side to get a port number from the information that acquired from xend,
> > > > the acquisition of a port number will be easy.
> > > >
> > > > > this is a very small niche usecase
> > > > I do not think so. and I think that there is a person to need surely.
> > > > Because, I think that it can perform the prevention / maintenance
> > > > by the pair of guest and port-number are managed.
> > > > For example, The person who thinks about maintenance for the port which opened out
> > > > had better be a fixed port number.
> > > > If it does't know whether it has already opened or it will open out from now on,
> > > > it will become difficult to deal with possibility of attack to an opening port.
> > > > Therefore,
> > > > the user who wants to open only a specific port for a firewall needs to fixed port number.
> > > > And, even if it can get a dynamic port from remote connection in the future,
> > > > he needs a fixed port number at the time of remote connection too,
> > > > because he wants to connection with only a specific port.
> > >
> > > There's two possibilities to consider:
> > >
> > > a. The admin of the Dom0 permanently opens up a range of ports (eg 5900->5920) to allow
> > > upto 20 vms to have their console accessed at any time. In this case, whether you
> > > use fixed or dynamic ports per VM, you still need 20 ports open, to run 20 consoles.
> > >
> > > b. The admin of the Dom0 only opens specific ports for short periods of time. In this
> > > case the admin will have to lookup what port corresponds to a VM, so it doesn't matter
> > > whether we're using fixed or dynamic ports, the admin still has same amount of work
> > > to lookup a port.
> > >
> > > So, I still don't see that using fixed ports in virt-manager has any benefit for the
> > > administration POV.
> > >
> > > Neither of these two options are entirely satisfactory though - it would be desirable
> > > to only open up a port when explicitly needed, and not require the admin to do any
> > > work. One might even suggest that libvirt should have some form of API to let the
> > > remote user request access to the cosnole - authenticated of course
> > >
> > >
> > > virDomainAllowConsole(virDomainPtr, const char *ipaddr);
> > > virDomainDisallowConsole(virDomainPtr, const char *ipaddr);
> > >
> > > Calling either of these functions would add neccessary iptables rule to allow
> > > access to the console for that particular domain, from the specified ip address.
> > > When the virConnectPtr object was closed, then any rules would also automatically
> > > be removed.
> > >
> > > This would allow virt-manager to securely request access to the console without
> > > needing permanent iptables rules.
> > >
> > > These's probably quite a bit more to think about wrt to iptables, consoles
> > > and seecure authentication. In the very near future libvirt will have the
> > > support for remote management merged and we'll be in a position to experiment
> > > with these ideas for real. So I don't think we want to add support for fixed
> > > port numbers in the virt-manager wizard until we've tried out some of these
> > > ideas.
> > >
> > > Regards,
> > > Dan.
> > > --
> > > |=- Red Hat, Engineering, Emerging Technologies, Boston. +1 978 392 2496 -=|
> > > |=- Perl modules: http://search.cpan.org/~danberr/ -=|
> > > |=- Projects: http://freshmeat.net/~danielpb/ -=|
> > > |=- GnuPG: 7D3B9505 F3C9 553F A1DA 4AC2 5648 23C1 B3DF F742 7D3B 9505 -=|
> > >
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