Subject: Re: [vserver] util-vserver & cpuset bug ?
From: Ed W <lists@wildgooses.com>
Date: Thu, 16 Jul 2009 01:10:48 +0100
Thu, 16 Jul 2009 01:10:48 +0100
Hi

> well, you have a bunch of options, depending on the
> specific usecase ... e.g.
>   

Assuming headless server somewhere in a rack.

>  - use a real console (serial or vga)
>  - use a virtual console
>   

Excuse dim question, but presumably the latter (and former) of these is 
out if we aren't on the physical terminal?

>  - use a pipe or unix socket
>  - use a network socket 
>   

Again, probably dim question, but by this do you mean some variation of 
ssh, telnet or home grown equivalent using netcat/shells, etc?

>> SSH is a given, but isn't always a straightforward option 
>> if IP addresses are constrained
>>     
>
> AFAIK, there is no constraint on private IP addresses
> (yet, although the IPV6 folks would like to see that
> on IPV4 :), so the public IP address constrains are
> not a real reason for not using ssh or telnet
>   

Well, kind of.  However, it's certainly more convenient to run all 
services on port 22 on real IPs. 

At least for my data center machines I obviously need to talk to real 
IPs at some point and obviously one IP is enough if use an array of 
ports, but remembering how they all map is a pain.  Someone will say to 
configure some file in ~/.ssh which lets you setup these mappings, but I 
hop around between a bunch of linux, windows and mac terminals and 
keeping such a file up to date is not ideal.  (DNS solves the problem 
neatly in the case of lots of IPs!)

I guess it would be possible to setup a gateway (vserver?) which you ssh 
into and then from there into the real server.  Add some scripts and I 
can see that working

However, quite often when I'm doing maintenance and leaping into 
machines to check config (and some machines are just templates, so they 
get fired up with incorrect ip addresses), it's definitely extremely 
convenient to be able to use "enter"

Grateful for any other ideas?

Thanks

Ed W


Hi

well, you have a bunch of options, depending on the
specific usecase ... e.g.
  

Assuming headless server somewhere in a rack.

 - use a real console (serial or vga)
 - use a virtual console
  

Excuse dim question, but presumably the latter (and former) of these is out if we aren't on the physical terminal?

 - use a pipe or unix socket
 - use a network socket 
  

Again, probably dim question, but by this do you mean some variation of ssh, telnet or home grown equivalent using netcat/shells, etc?

SSH is a given, but isn't always a straightforward option 
if IP addresses are constrained
    

AFAIK, there is no constraint on private IP addresses
(yet, although the IPV6 folks would like to see that
on IPV4 :), so the public IP address constrains are
not a real reason for not using ssh or telnet
  

Well, kind of.  However, it's certainly more convenient to run all services on port 22 on real IPs. 

At least for my data center machines I obviously need to talk to real IPs at some point and obviously one IP is enough if use an array of ports, but remembering how they all map is a pain.  Someone will say to configure some file in ~/.ssh which lets you setup these mappings, but I hop around between a bunch of linux, windows and mac terminals and keeping such a file up to date is not ideal.  (DNS solves the problem neatly in the case of lots of IPs!)

I guess it would be possible to setup a gateway (vserver?) which you ssh into and then from there into the real server.  Add some scripts and I can see that working

However, quite often when I'm doing maintenance and leaping into machines to check config (and some machines are just templates, so they get fired up with incorrect ip addresses), it's definitely extremely convenient to be able to use "enter"

Grateful for any other ideas?

Thanks

Ed W