Re: DHCP server that itself gets an IP address by DHCP

From	Reco <recoverym4n@gmail.com>
Newsgroups	linux.debian.user
Subject	Re: DHCP server that itself gets an IP address by DHCP
Date	2017-08-24 22:40 +0200
Message-ID	<ui750-2Q6-17@gated-at.bofh.it> (permalink)
References	<uhWMh-4E5-7@gated-at.bofh.it> <ui6Vj-2MH-3@gated-at.bofh.it>
Organization	linux.* mail to news gateway

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	Hi.

On Thu, 24 Aug 2017 22:21:04 +0200
Pascal Hambourg <pascal@plouf.fr.eu.org> wrote:

> Le 24/08/2017 à 11:30, Reco a écrit :
> > 
> > Somewhat hackish, but straightforward way to achieve this is to redirect
> > DNS requests from your LAN to correct DNS. Something like this should do
> > the trick:
> 
> Not so straightforward because you still need to get the ISP's DNS and 
> update the iptables rules whenever the DNS change.

Appropriate dhclient hook should do this trick.
I'd start with copying and modifying resolvconf one.


> > iptables -t nat -A OUTPUT -i <LAN Port> -p udp --dport 53 \
> > -j DNAT --to-destination <ISP DNS>:53
> > 
> > iptables -t nat -A OUTPUT -i <LAN Port> -p tcp --dport 53 \
> > -j DNAT --to-destination <ISP DNS>:53
> 
> You mean "-A PREROUTING".

My mistake indeed. OUTPUT is unsuitable here.

Reco

Thread

Re: DHCP server that itself gets an IP address by DHCP Reco <recoverym4n@gmail.com> - 2017-08-24 11:40 +0200
  threading, was Re: DHCP server that itself gets an IP address by DHCP David Wright <deblis@lionunicorn.co.uk> - 2017-08-24 15:30 +0200
    Re: threading, was Re: DHCP server that itself gets an IP address  by DHCP Reco <recoverym4n@gmail.com> - 2017-08-24 17:10 +0200
  Re: DHCP server that itself gets an IP address by DHCP Pascal Hambourg <pascal@plouf.fr.eu.org> - 2017-08-24 22:30 +0200
    Re: DHCP server that itself gets an IP address by DHCP Greg Wooledge <wooledg@eeg.ccf.org> - 2017-08-24 22:40 +0200
      Re: DHCP server that itself gets an IP address by DHCP Mark Fletcher <mark27q1@gmail.com> - 2017-08-25 00:40 +0200
        Re: DHCP server that itself gets an IP address by DHCP Greg Wooledge <wooledg@eeg.ccf.org> - 2017-08-25 14:20 +0200
          Re: DHCP server that itself gets an IP address by DHCP Mark Fletcher <mark27q1@gmail.com> - 2017-08-25 15:20 +0200
            Re: DHCP server that itself gets an IP address by DHCP Greg Wooledge <wooledg@eeg.ccf.org> - 2017-08-25 16:00 +0200
    Re: DHCP server that itself gets an IP address by DHCP Reco <recoverym4n@gmail.com> - 2017-08-24 22:40 +0200
      Re: DHCP server that itself gets an IP address by DHCP Mark Fletcher <mark27q1@gmail.com> - 2017-08-25 00:30 +0200
        Re: DHCP server that itself gets an IP address by DHCP Reco <recoverym4n@gmail.com> - 2017-08-25 10:20 +0200
        Re: DHCP server that itself gets an IP address by DHCP Greg Wooledge <wooledg@eeg.ccf.org> - 2017-08-25 14:20 +0200

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