Re: [Xen-users] VM slow after being unused for a while

["Itamar Reis Peixoto" <itamar@xxxxxxxxxxxxxxxx>]

you're right.

:-)


--------------------

Itamar Reis Peixoto

e-mail: itamar@xxxxxxxxxxxxxxxx
msn: itamarjp@xxxxxxxxxxxxx
skype: itamarjp 
icq: 81053601
+55 34 3238 3845
+55 11 4063 5033


From: "Nico Kadel-Garcia" <nkadel@xxxxxxxxx>
To: "Itamar Reis Peixoto" <itamar@xxxxxxxxxxxxxxxx>
Cc: "Nasse Gris" <nassegris@xxxxxxxxx>; <xen-users@xxxxxxxxxxxxxxxxxxx>
Sent: Saturday, May 12, 2007 6:15 AM
Subject: Re: [Xen-users] VM slow after being unused for a while


> Itamar Reis Peixoto wrote:
> > try to edit /etc/ssh/sshd_config
> >  
> > and change UseDNS to NO
> >  
> > restart ssh server
> >  
> > --------------------
> >  
> > Itamar Reis Peixoto
> >  
> Unfortunately, that argument doesn't do what you think it does.  And it 
> confuses a lot of people!
> Here's the situation at least up through OpenSSH 3.9p1.
>
> OpenSSH, for logging purposes, does a reverse DNS on any contacting IP 
> address. The UseDNS option says whether to verify that the reverse DNS 
> matches a valid forward DNS for that host. But disabling UseDNS does 
> *NOT, NOT, NOT* turn off the reverse DNS lookup! Any number of us have 
> submitted patches for this over the years: I submitted some when I dealt 
> with large remotely deployed networks. (When you manage thousands of 
> machines deployed in data centers all over the world, you can be 
> absolutely certain a lot of them will not have valid reverse DNS, or 
> even have DNS working properly, and you need to be able to log in 
> quickly in a crunch.)
> The option you need is in your sshd init script. You need to use the 
> additional options "-u 0", to set the namelength of the recorded DNS 
> entry to 0 so that the reverse DNS isn't actually done. (Why the SSH 
> authors think setting an arglength to 0 should cause undocumented 
> behavior and not throw an error, instead of obeying the UseDNS option in 
> the configuraton file more correctly, I leave to people who think the 
> "chroot" option of OpenSSH actually means a chroot cage for SSH users to 
> protect them from accessing the filesystem outside their home directory. 
> It doesn.t.)
> I like OpenSSH, I use it a lot, but I've disagreed volubly with the 
> authors on a few points over the years. This is one of them.
_______________________________________________
Xen-users mailing list
Xen-users@xxxxxxxxxxxxxxxxxxx
http://lists.xensource.com/xen-users