[Xen-devel] [PATCH] get dhcp working for network-nat (Take 2)

["Dan Magenheimer" <dan.magenheimer@xxxxxxxxxx>]

I fixed up the previous patch to resolve a couple of problems and
make a couple of things more automatic. The patch now works on
RHEL5, SLES10, and Ubuntu7.04, and applies to xen-unstable.  With
this patch, it is now (relatively) easy to use dom0 as a DHCP
server for all domU's running on the machine.

Please apply.

Signed-off-by: Dan Magenheimer <dan.magenheimer@xxxxxxxxxx>

Thanks,
Dan

P.S. Here's the manual steps required to to get it to work.

1) Install the dhcp package on dom0 using your distro's tools
2) Modify /etc/dhcpd.conf to look like this:
        ddns-update-style interim;
        deny client-updates;
        authoritative;
        option domain-name-servers dnsip1 dnsip2;
        option ntp-servers ntpip1 ntpip2 ntpip3;
        default-lease-time 14400;
        max-lease-time 172800;
   where dnsip1 etc are of course all real IPv4 addresses.
   The ntp-servers line can be removed if desired.  A subnet
   line for 10.0.0.0/8 is added automagically by the tools.
3) Modify /etc/xen/xend-config.sxp
   - comment the line (network-script network-bridge)
   - comment the line (vif-script vif-bridge)
   - uncomment (network-script network-nat)
   - uncomment (vif-script vif-nat)
4) Reboot or restart xend
5) Launch a domain for which the primary interface
   is configured for dhcp
   - change name= in your config file to something
     useful first as this will be the machine name
     given to it by dhcp
6) Try out networking in your VM!

> -----Original Message-----
> From: Dan Magenheimer [mailto:dan.magenheimer@xxxxxxxxxx]
> Sent: Wednesday, January 16, 2008 3:49 PM
> To: 'xen-devel@xxxxxxxxxxxxxxxxxxx'
> Subject: [PATCH] get dhcp working for network-nat
> 
> 
> Has anybody successfully used the network-nat script, with or without
> dhcp?  The existing documentation around this is fairly poor, so if
> youâve seen it âjust workâ (or with only some minor tweaks),
> please reply.  Iâm not much of a networking expert so I hope my
> time on this wasnât wasted.
> 
> Assuming not (and supported by google search), perhaps network-nat has
> been broken for a long time?  It certainly has not received much love
> recently and many mailing list queries about it have gone unanswered.
> 
> That said, here's my situation:
> 
> Due to limited IP availability in my office, I wanted to configure a
> setup where dom0 works like an inexpensive home router (e.g. Linksys,
> Dlink,Belkin), which does NAT and DHCP for multiple attached (or
> wireless) machines.  So I need dom0 to both provide network address
> translation and to serve dhcp addresses to any VM's launched on it.
> 
> It appears that this should work.  Or maybe once upon a time it did
> work.  But I had to muck around with it quite a bit and spin a patch
> to get it work with 3.1 bits.  And since the key files haven't been
> changed in over a year, though untested as of yet, I think the same
> patch and process is necessary on xen-unstable.
> 
> Also, this is tested on a RHEL5-based dom0.  I don't know much about
> dhcp implementations on other distros and haven't tried this recipe
> on other distros, so your mileage may vary but please do provide
> feedback if this patch will fail on your favorite distro.
> 
> Here's the process I used:
> 1) Install the dhcp package using your distro's tools
> 2) Modify /etc/dhcpd.conf to look like this:
>       ddns-update-style interim;
>       deny client-updates;
>       authoratitive;
>       option domain-name-servers dnsip1 dnsip2;
>       option ntp-servers ntpip1 ntpip2 ntpip3;
>       default-lease-time 14400;
>       max-lease-time 172800;
>       subnet 10.0.0.0 netmask 255.0.0.0 {}
>    where dnsip1 etc are of course all real IPv4 addresses.
>    The ntp-servers line can be removed if desired.
> 3) Apply the attached patch.  The patch applies to
>    xen-3.1-testing.hg and you will need to apply
>    it to the same files in /etc/xen/scripts.
> 4) Modify /etc/xen/xend-config.sxp
>    - comment the line (network-script network-bridge)
>    - comment the line (vif-script vif-bridge)
>    - uncomment (network-script network-nat)
>    - uncomment (vif-script vif-nat)
> 5) Modify /etc/xen/scripts/network-nat
>    - change dhcp=${dhcp:-no} from no to yes
> 6) Modify /etc/xen/scripts/vif-nat
>    - change dhcp=${dhcp:-no} from no to yes
> 7) Restart xend (probably "service xend restart")
> 8) Launch a domain for which the primary interface
>    is configured for dhcp (pv and pvhvm tested so
>    far; don't know if hvm works yet)
>    - change name= in your config file to something
>      useful first as this will be the machine name
>      given to it by dhcp
> 9) Try out networking in your VM!
> 
> This patch could use some tweaking... the code to add
> and remove vifâs from /etc/sysconfig/dhcpd needs some
> work.  But I thought it would be good to get others
> trying this version out.  If the patch doesnât work
> on your distro, this is a good place to tweak.
> 
> Finally, Iâm not sure if nat without dhcp is used much.
> Iâd like to propose that the default for dhcp (see steps
> 5 and 6) be changed from no to yes.
> 
> Thanks for any feedback!
> Dan
>

Attachment: dhcp2.patch
Description: Binary data

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