FAQ
Hi all,

Does anyone know, if it's possible to reroute all (i.e. HTTP / FTP /
DNS / SMTP / POP3 / IMAP / etc) from an ADSL connected machine via
another server, which is currently hosted with IS and has full
internet access?


i.e. Can I setup another machine, on a different public IP than the
dynamic ADSL IP as default gw? OR do I need todo something on that
machine to work as a router for such a setup?

Both servers in this case is CentOS linux, but I'm sure that won't
make a big difference?

--
Kind Regards
Rudi Ahlers
SoftDux

Website: http://www.SoftDux.com
Technical Blog: http://Blog.SoftDux.com
Office: 087 805 9573
Cell: 082 554 7532

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  • Simon Billis at Apr 28, 2010 at 1:26 pm

    Rudi Ahlers sent a missive on?2010-04-28:

    Hi all,

    Does anyone know, if it's possible to reroute all (i.e. HTTP / FTP /
    DNS / SMTP / POP3 / IMAP / etc) from an ADSL connected machine via
    another server, which is currently hosted with IS and has full
    internet access?


    i.e. Can I setup another machine, on a different public IP than the
    dynamic ADSL IP as default gw? OR do I need todo something on that
    machine to work as a router for such a setup?

    Both servers in this case is CentOS linux, but I'm sure that won't
    make a big difference?
    In principal yes you can do this type of thing. You'll have to enable
    ipforwarding on the gateway machine as a minimum.

    Can you provide more information about your networking setup - ip addresses
    and subnet masks, with an ascii drawing as well would help if you think it
    relevant :-), then we can provide detailed answers :-)

    Thanks

    Simon.
  • Rudi Ahlers at Apr 28, 2010 at 1:33 pm

    On Wed, Apr 28, 2010 at 3:26 PM, Simon Billis wrote:
    Rudi Ahlers sent a missive on?2010-04-28:
    Hi all,

    Does anyone know, if it's possible to reroute all (i.e. HTTP / FTP /
    DNS / SMTP / POP3 / IMAP / etc) from an ADSL connected machine via
    another server, which is currently hosted with IS and has full
    internet access?


    i.e. Can I setup another machine, on a different public IP than the
    dynamic ADSL IP as default gw? OR do I need todo something on that
    machine to work as a router for such a setup?

    Both servers in this case is CentOS linux, but I'm sure that won't
    make a big difference?
    In principal yes you can do this type of thing. You'll have to enable
    ipforwarding on the gateway machine as a minimum.

    Can you provide more information about your networking setup - ip addresses
    and subnet masks, with an ascii drawing as well would help if you think it
    relevant :-), then we can provide detailed answers :-)

    Thanks

    Simon.




    _______________________________________________

    Hi Simon,

    Thanx for the help :)


    The ADSL connected server currently runs on 196.210.176.x, and the
    internet connected server runs on 196.34.136.109

    So, there's not on the same subnets, by a mile. In fact, the 2 servers
    are seperated by about 30Km's, but I can get into both via the
    interner.

    Would ipforwarding still work, since I want to reroute all packets on
    eth0 of 196.34.136.109 in, and back out?

    --
    Kind Regards
    Rudi Ahlers
    SoftDux

    Website: http://www.SoftDux.com
    Technical Blog: http://Blog.SoftDux.com
    Office: 087 805 9573
    Cell: 082 554 7532
  • cahit Eyigünlü at Apr 28, 2010 at 1:35 pm
    Open vpn is a nice solution in my opinion

    2010/4/28 Rudi Ahlers <rudiahlers at gmail.com>
    On Wed, Apr 28, 2010 at 3:26 PM, Simon Billis wrote:
    Rudi Ahlers sent a missive on 2010-04-28:
    Hi all,

    Does anyone know, if it's possible to reroute all (i.e. HTTP / FTP /
    DNS / SMTP / POP3 / IMAP / etc) from an ADSL connected machine via
    another server, which is currently hosted with IS and has full
    internet access?


    i.e. Can I setup another machine, on a different public IP than the
    dynamic ADSL IP as default gw? OR do I need todo something on that
    machine to work as a router for such a setup?

    Both servers in this case is CentOS linux, but I'm sure that won't
    make a big difference?
    In principal yes you can do this type of thing. You'll have to enable
    ipforwarding on the gateway machine as a minimum.

    Can you provide more information about your networking setup - ip addresses
    and subnet masks, with an ascii drawing as well would help if you think it
    relevant :-), then we can provide detailed answers :-)

    Thanks

    Simon.




    _______________________________________________

    Hi Simon,

    Thanx for the help :)


    The ADSL connected server currently runs on 196.210.176.x, and the
    internet connected server runs on 196.34.136.109

    So, there's not on the same subnets, by a mile. In fact, the 2 servers
    are seperated by about 30Km's, but I can get into both via the
    interner.

    Would ipforwarding still work, since I want to reroute all packets on
    eth0 of 196.34.136.109 in, and back out?

    --
    Kind Regards
    Rudi Ahlers
    SoftDux

    Website: http://www.SoftDux.com
    Technical Blog: http://Blog.SoftDux.com
    Office: 087 805 9573
    Cell: 082 554 7532
    _______________________________________________
    CentOS mailing list
    CentOS at centos.org
    http://lists.centos.org/mailman/listinfo/centos
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  • Simon Billis at Apr 28, 2010 at 1:37 pm

    Simon Billis sent a missive on?2010-04-28:

    Rudi Ahlers sent a missive on?2010-04-28:
    Hi all,

    Does anyone know, if it's possible to reroute all (i.e. HTTP / FTP /
    DNS / SMTP / POP3 / IMAP / etc) from an ADSL connected machine via
    another server, which is currently hosted with IS and has full
    internet access?


    i.e. Can I setup another machine, on a different public IP than the
    dynamic ADSL IP as default gw? OR do I need todo something on that
    machine to work as a router for such a setup?

    Both servers in this case is CentOS linux, but I'm sure that won't
    make a big difference?
    In principal yes you can do this type of thing. You'll have to enable
    ipforwarding on the gateway machine as a minimum.

    Can you provide more information about your networking setup - ip
    addresses and subnet masks, with an ascii drawing as well would help
    if you think it relevant :-), then we can provide detailed answers :-)

    Thanks

    Simon.
    Sorry miss read your post - you can do what you're after, but this is a
    proxy in this case.... i.e. the remote box is acting as a proxy for your
    adsl connected server. If you're wanting to route all the traffic from your
    adsl connected box to the remote server, then I would look at using a VPN
    between the boxes.... you might be able to use squid on the remote server to
    be your proxy also.

    S.
  • Mark Roth at Apr 28, 2010 at 1:49 pm

    Rudi wrote:
    Does anyone know, if it's possible to reroute all (i.e. HTTP / FTP /
    DNS / SMTP / POP3 / IMAP / etc) from an ADSL connected machine via
    another server, which is currently hosted with IS and has full
    internet access?

    i.e. Can I setup another machine, on a different public IP than the
    dynamic ADSL IP as default gw? OR do I need todo something on that
    machine to work as a router for such a setup?
    <snip>
    I don't quite understand what you're asking. Do you mean
    <ADSL system><-><hosted system><->the 'Net
    or do you mean
    <the 'Net>-><hosted system>-><ADSL system>
    ?
    That is, are you trying to offer Web, FTP (BAD idea, use sftp or scp), and
    email from your ADSL-connected server, or do you want to connect to the
    'Net via the hosted system?

    mark
  • Rudi Ahlers at Apr 28, 2010 at 1:55 pm

    On Wed, Apr 28, 2010 at 3:49 PM, wrote:
    Rudi wrote:
    Does anyone know, if it's possible to reroute all (i.e. HTTP / FTP /
    DNS / SMTP / POP3 / IMAP / etc) from an ADSL connected machine via
    another server, which is currently hosted with IS and has full
    internet access?

    i.e. Can I setup another machine, on a different public IP than the
    dynamic ADSL IP as default gw? OR do I need todo something on that
    machine to work as a router for such a setup?
    <snip>
    I don't quite understand what you're asking. Do you mean
    ?<ADSL system><-><hosted system><->the 'Net
    or do you mean
    <the 'Net>-><hosted system>-><ADSL system>
    ?
    That is, are you trying to offer Web, FTP (BAD idea, use sftp or scp), and
    email from your ADSL-connected server, or do you want to connect to the
    'Net via the hosted system?

    ? ? ?mark

    _______________________________________________


    Mark,

    We, in South Africa sit with a huge problem in that our clients can't
    connect to the rest of the world cause SEACOM is down. i.e. our client
    can, for the past 3 days, only surf local (i.e. local in South Africa)
    websites, email, etc. We have a lot of client's servers hosted in the
    USA, so they can't reach their websites or email and business is
    standing still for them.


    So, I want to reroute all their traffic via one of our other servers
    which right now has got full internet access, as such:


    <ADSL client> - <Limited internet> - <server> - <full internet>


    I already setup squid for this and it works great, but doesn't proxy
    SMTP / POP3 / Skype / IM / RDP / etc etc. And I don't want to setup a
    proxy service for evey service imaginible.


    --
    Kind Regards
    Rudi Ahlers
    SoftDux

    Website: http://www.SoftDux.com
    Technical Blog: http://Blog.SoftDux.com
    Office: 087 805 9573
    Cell: 082 554 7532
  • Eero Volotinen at Apr 28, 2010 at 1:59 pm

    2010/4/28 Rudi Ahlers <rudiahlers at gmail.com>:
    On Wed, Apr 28, 2010 at 3:49 PM, ?wrote:
    Rudi wrote:
    Does anyone know, if it's possible to reroute all (i.e. HTTP / FTP /
    DNS / SMTP / POP3 / IMAP / etc) from an ADSL connected machine via
    another server, which is currently hosted with IS and has full
    internet access?

    i.e. Can I setup another machine, on a different public IP than the
    dynamic ADSL IP as default gw? OR do I need todo something on that
    machine to work as a router for such a setup?
    <snip>
    I don't quite understand what you're asking. Do you mean
    ?<ADSL system><-><hosted system><->the 'Net
    or do you mean
    <the 'Net>-><hosted system>-><ADSL system>
    ?
    That is, are you trying to offer Web, FTP (BAD idea, use sftp or scp), and
    email from your ADSL-connected server, or do you want to connect to the
    'Net via the hosted system?

    ? ? ?mark

    _______________________________________________


    Mark,

    We, in South Africa sit with a huge problem in that our clients can't
    connect to the rest of the world cause SEACOM is down. i.e. our client
    can, for the past 3 days, only surf local (i.e. local in South Africa)
    websites, email, etc. We have a lot of client's servers hosted in the
    USA, so they can't reach their websites or email and business is
    standing still for them.


    So, I want to reroute all their traffic via one of our other servers
    which right now has got full internet access, as such:


    <ADSL client> - <Limited internet> - <server> - <full internet>


    I already setup squid for this and it works great, but doesn't proxy
    SMTP / POP3 / Skype / IM / RDP / etc etc. And I don't want to setup a
    proxy service for evey service imaginible.
    how about ipsec / openvpn tunnel and routing traffic via it?

    --
    Eero,
    RHCE
  • Rudi Ahlers at Apr 28, 2010 at 2:02 pm

    On Wed, Apr 28, 2010 at 3:59 PM, Eero Volotinen wrote:
    how about ipsec / openvpn tunnel and routing traffic via it?

    --
    Eero,
    RHCE
    _______________________________________________
    I don't know, since I've never setup one ;)

    The trickey part, which I don't understand, is how will this work.


    i.e. I SSH into ADSL client's machine, and setup the VPN. The VPN then
    connects to our linux server which now acts as gateway. How do I tell
    the client's linux server to rout all traffic (apart from my SSH
    connection, otherwise I get cut-off) via the VPN, and not via the same
    ADSL line on top of which the VPN runs?

    --
    Kind Regards
    Rudi Ahlers
    SoftDux

    Website: http://www.SoftDux.com
    Technical Blog: http://Blog.SoftDux.com
    Office: 087 805 9573
    Cell: 082 554 7532
  • Mark Roth at Apr 28, 2010 at 2:06 pm
    Rudi,

    Rudi wrote:
    On Wed, Apr 28, 2010 at 3:49 PM, wrote:
    Rudi wrote:
    Does anyone know, if it's possible to reroute all (i.e. HTTP / FTP /
    DNS / SMTP / POP3 / IMAP / etc) from an ADSL connected machine via
    another server, which is currently hosted with IS and has full
    internet access?

    i.e. Can I setup another machine, on a different public IP than the
    dynamic ADSL IP as default gw? OR do I need todo something on that
    machine to work as a router for such a setup?
    <snip>
    I don't quite understand what you're asking. Do you mean
    ?<ADSL system><-><hosted system><->the 'Net
    or do you mean
    <the 'Net>-><hosted system>-><ADSL system>
    ?
    That is, are you trying to offer Web, FTP (BAD idea, use sftp or scp),
    and email from your ADSL-connected server, or do you want to connect to
    the 'Net via the hosted system?
    We, in South Africa sit with a huge problem in that our clients can't
    connect to the rest of the world cause SEACOM is down. i.e. our client
    can, for the past 3 days, only surf local (i.e. local in South Africa)
    websites, email, etc. We have a lot of client's servers hosted in the
    USA, so they can't reach their websites or email and business is
    standing still for them.

    So, I want to reroute all their traffic via one of our other servers
    which right now has got full internet access, as such:

    <ADSL client> - <Limited internet> - <server> - <full internet>
    <snip>
    AH! The light dawns! <g>

    Sounds to me as though you need to have the clients use the hosted system
    as their gateway, as though they're on a subnet, and have to go through
    the hosted system as a firewall (not a bad idea in itself). They need to
    *not* look directly out.

    Sounds like an iptables setup to route through the hosted system.
    Remember, if that works for you, that all the rules for blocking should
    happen *first* in /etc/sysconfig/iptables.

    mark
  • Rudi Ahlers at Apr 28, 2010 at 2:14 pm

    On Wed, Apr 28, 2010 at 4:06 PM, wrote:

    AH! The light dawns! <g>

    Sounds to me as though you need to have the clients use the hosted system
    as their gateway, as though they're on a subnet, and have to go through
    the hosted system as a firewall (not a bad idea in itself). They need to
    *not* look directly out.

    Sounds like an iptables setup to route through the hosted system.
    Remember, if that works for you, that all the rules for blocking should
    happen *first* in /etc/sysconfig/iptables.

    ? ? ? ? ?mark


    _______________________________________________

    Hi Mark,

    That's right :)

    But, I don't know how todo this, or what todo....... And I don't know
    what to look for on the internet to help me with this either.

    What makes it different that what I've setup before is that it's not
    really a LAN anymore, so I can't just tell the ADSL connected server
    to use the hosted server as gateway, I don't think that'll work.

    --
    Kind Regards
    Rudi Ahlers
    SoftDux

    Website: http://www.SoftDux.com
    Technical Blog: http://Blog.SoftDux.com
    Office: 087 805 9573
    Cell: 082 554 7532
  • Mark Roth at Apr 28, 2010 at 2:32 pm
    Rudy,

    Rudi wrote:
    On Wed, Apr 28, 2010 at 4:06 PM, wrote:

    AH! The light dawns! <g>

    Sounds to me as though you need to have the clients use the hosted
    system as their gateway, as though they're on a subnet, and have to go
    through the hosted system as a firewall (not a bad idea in itself). They
    need to *not* look directly out.

    Sounds like an iptables setup to route through the hosted system.
    Remember, if that works for you, that all the rules for blocking should
    happen *first* in /etc/sysconfig/iptables.
    That's right :)

    But, I don't know how todo this, or what todo....... And I don't know
    what to look for on the internet to help me with this either.
    *sigh*
    I was just thinking about this, and I think the answer is
    $ route add -net 0.0.0.0 gw <hosted IP> eth0
    What makes it different that what I've setup before is that it's not
    really a LAN anymore, so I can't just tell the ADSL connected server
    to use the hosted server as gateway, I don't think that'll work.
    What's not really a LAN anymore - does the ADSL server have people using
    that as a gateway?

    mark
  • Rudi Ahlers at Apr 28, 2010 at 2:35 pm

    On Wed, Apr 28, 2010 at 4:32 PM, wrote:
    Rudy,

    Rudi wrote:
    On Wed, Apr 28, 2010 at 4:06 PM, ?wrote:
    AH! The light dawns! <g>

    Sounds to me as though you need to have the clients use the hosted
    system as their gateway, as though they're on a subnet, and have to go
    through the hosted system as a firewall (not a bad idea in itself). They
    need to *not* look directly out.

    Sounds like an iptables setup to route through the hosted system.
    Remember, if that works for you, that all the rules for blocking should
    happen *first* in /etc/sysconfig/iptables.
    That's right :)

    But, I don't know how todo this, or what todo....... And I don't know
    what to look for on the internet to help me with this either.
    *sigh*
    I was just thinking about this, and I think the answer is
    $ route add -net 0.0.0.0 gw <hosted IP> eth0
    ok, let's try ? this tells it to route all traffic, including my SSH
    connection to the gateway, rigth. But, what do I need todo on the
    gateway, since the gateway will route incoming & outgoing traffic over
    the same interface, eth0


    What makes it different that what I've setup before is that it's not
    really a LAN anymore, so I can't just tell the ADSL connected server
    to use the hosted server as gateway, I don't think that'll work.
    What's not really a LAN anymore - does the ADSL server have people using
    that as a gateway?
    Yes, in this case there's 5 PC's behing the Linux gateway

    ? ? ?mark

    _______________________________________________
    CentOS mailing list
    CentOS at centos.org
    http://lists.centos.org/mailman/listinfo/centos


    --
    Kind Regards
    Rudi Ahlers
    SoftDux

    Website: http://www.SoftDux.com
    Technical Blog: http://Blog.SoftDux.com
    Office: 087 805 9573
    Cell: 082 554 7532
  • Bart Schaefer at Apr 28, 2010 at 2:36 pm

    On Wed, Apr 28, 2010 at 6:55 AM, Rudi Ahlers wrote:
    Mark,

    We, in South Africa sit with a huge problem in that our clients can't
    connect to the rest of the world cause SEACOM is down. i.e. our client
    can, for the past 3 days, only surf local (i.e. local in South Africa)
    websites, email, etc.

    So, I want to reroute all their traffic via one of our other servers

    <ADSL client> - <Limited internet> - <server> - <full internet>
    I'm rather rusty on the details of this, but isn't the correct way to
    handle this to have <server> publish an ARP route indicating that it
    provides routing to (the IP space containing) <ADSL client>?

    Any mere proxy or VPN hosted at <server> will allow <ADSL client> to
    transparently establish connections, but won't allow <full internet>
    to reach the IP address of <ADSL client> (nor anything else in
    <Limited internet>). Maybe that's not needed here.
  • Rudi Ahlers at Apr 28, 2010 at 2:39 pm

    On Wed, Apr 28, 2010 at 4:36 PM, Bart Schaefer wrote:
    On Wed, Apr 28, 2010 at 6:55 AM, Rudi Ahlers wrote:
    Mark,

    We, in South Africa sit with a huge problem in that our clients can't
    connect to the rest of the world cause SEACOM is down. i.e. our client
    can, for the past 3 days, only surf local (i.e. local in South Africa)
    websites, email, etc.

    So, I want to reroute all their traffic via one of our other servers

    <ADSL client> - <Limited internet> - <server> - <full internet>
    I'm rather rusty on the details of this, but isn't the correct way to
    handle this to have <server> publish an ARP route indicating that it
    provides routing to (the IP space containing) <ADSL client>?

    Any mere proxy or VPN hosted at <server> will allow <ADSL client> to
    transparently establish connections, but won't allow <full internet>
    to reach the IP address of <ADSL client> (nor anything else in
    <Limited internet>). ?Maybe that's not needed here.
    _______________________________________________
    CentOS mailing list
    CentOS at centos.org
    http://lists.centos.org/mailman/listinfo/centos

    I don't know either.......

    And I haven't been able to install openvpn on the ADSL hosted server
    either, so I want to try a gateway type setup


    --
    Kind Regards
    Rudi Ahlers
    SoftDux

    Website: http://www.SoftDux.com
    Technical Blog: http://Blog.SoftDux.com
    Office: 087 805 9573
    Cell: 082 554 7532
  • Simon Billis at Apr 28, 2010 at 2:57 pm
    Rudi Ahlers sent a missive on?2010-04-28:
    And I haven't been able to install openvpn on the ADSL hosted server
    either, so I want to try a gateway type setup
    Having given this some thought I think that you would do better to provide
    proxy services on a case by case basis.

    Attempting to route traffic using a default gateway I don't think is going
    to work... the "next hop" is not on a local subnet so I don?t think this is
    going to work (I might be wrong about this).

    You could have a vpn between the machines - the ADSL gateway machine have a
    VPN to the IS machine and all traffic from and to the ADSL machine/NAT
    network behind it is routed over the VPN. This does work and is fairly easy
    to set-up if you have access to the ADSL machine.

    If you can't set this up then I think that you should concentrate on
    providing proxy services for essential services i.e. http, smtp, pop3, imap,
    ftp (if needed). Squid will do some, you can then use a mail server of your
    choice to provide smtp relay services, I think that there is a pop3/imap
    proxy out there also (I've never used one though). For such services the
    adsl gateway machine can then do DNAT on the outbound packet (using iptables
    prerouting table) and then the proxied service will then do its thing
    (hopefully).

    By far the best solution requiring little effort is a vpn (imho).

    Rgds

    Simon.
  • Karanbir Singh at Apr 28, 2010 at 1:52 pm

    On 04/28/2010 02:11 PM, Rudi Ahlers wrote:
    Hi all,

    Does anyone know, if it's possible to reroute all (i.e. HTTP / FTP /
    DNS / SMTP / POP3 / IMAP / etc) from an ADSL connected machine via
    another server, which is currently hosted with IS and has full
    internet access?
    all you need is 'man ip'. Setup the right gateways on each machine,
    setup your ip policy into the right rules, route the rules from / to
    wherever you want.

    - KB
  • John Doe at Apr 28, 2010 at 2:31 pm
    From: Rudi Ahlers <rudiahlers at gmail.com>
    Does anyone know, if it's possible to reroute all (i.e. HTTP /
    FTP / DNS / SMTP / POP3 / IMAP / etc) from an ADSL connected
    machine via another server, which is currently hosted with IS and
    has full internet access?
    i.e. Can I setup another machine, on a different public IP than the
    dynamic ADSL IP as default gw? OR do I need todo something on
    that machine to work as a router for such a setup?
    Maybe you wann have a look at: http://lartc.org/howto/

    JD
  • Rudi Ahlers at Apr 28, 2010 at 2:37 pm

    On Wed, Apr 28, 2010 at 4:31 PM, John Doe wrote:
    From: Rudi Ahlers <rudiahlers at gmail.com>
    Does anyone know, if it's possible to reroute all (i.e. HTTP /
    FTP / DNS / SMTP / POP3 / IMAP / etc) from an ADSL connected
    machine via another server, which is currently hosted with IS and
    has full internet access?
    i.e. Can I setup another machine, on a different public IP than the
    dynamic ADSL IP as default gw? OR do I need todo something on
    that machine to work as a router for such a setup?
    Maybe you wann have a look at: http://lartc.org/howto/

    JD


    Thanx JD. I can't load the site though, what is on it?



    --
    Kind Regards
    Rudi Ahlers
    SoftDux

    Website: http://www.SoftDux.com
    Technical Blog: http://Blog.SoftDux.com
    Office: 087 805 9573
    Cell: 082 554 7532
  • Simon Billis at Apr 28, 2010 at 2:42 pm

    Rudi Ahlers sent a missive on?2010-04-28:
    On Wed, Apr 28, 2010 at 4:31 PM, John Doe wrote:
    From: Rudi Ahlers <rudiahlers at gmail.com>
    Does anyone know, if it's possible to reroute all (i.e. HTTP / FTP
    / DNS / SMTP / POP3 / IMAP / etc) from an ADSL connected machine
    via another server, which is currently hosted with IS and has full
    internet access?
    i.e. Can I setup another machine, on a different public IP than the
    dynamic ADSL IP as default gw? OR do I need todo something on that
    machine to work as a router for such a setup?
    Maybe you wann have a look at: http://lartc.org/howto/

    JD


    Thanx JD. I can't load the site though, what is on it?

    It?s the Linux Advanced Routing & Traffic Control HOWTO
  • Dan Irwin at Apr 29, 2010 at 12:54 am

    -----Original Message-----
    From: centos-bounces at centos.org
    [mailto:centos-bounces at centos.org] On Behalf Of Rudi Ahlers
    Sent: Wednesday, 28 April 2010 11:11 PM
    To: CentOS mailing list
    Subject: [CentOS] how to reroute all ADSL traffic via another
    server on theinternet?

    Hi all,

    Does anyone know, if it's possible to reroute all (i.e. HTTP / FTP /
    DNS / SMTP / POP3 / IMAP / etc) from an ADSL connected machine via
    another server, which is currently hosted with IS and has full
    internet access?


    i.e. Can I setup another machine, on a different public IP than the
    dynamic ADSL IP as default gw? OR do I need todo something on that
    machine to work as a router for such a setup?

    Both servers in this case is CentOS linux, but I'm sure that won't
    make a big difference?
    You could use GRE tunnelling, which is supported by Linux and Cisco
    among others.

    You could set up a GRE tunnel between your two sites, assign a /30 for
    the link, and route most traffic over the GRE interface (Minus the IP
    Address of your remote site - it must be routed via your internet
    connection).

    This will behave as a point-to-point link between your sites.

    Check out the ip(8) command, in particular the ip tunnel commands.

    But, something like this should be a nice start:

    ip tunnel add Tunnel0 mode GRE remote 1.2.3.4

    ifconfig Tunnel0 10.10.10.1 netmask 255.255.255.252

    ip route add 1.2.3.4/32 via 6.7.8.9

    Cheers,

    Dan
  • Les Mikesell at Apr 29, 2010 at 1:08 am

    Dan Irwin wrote:
    -----Original Message-----
    From: centos-bounces at centos.org
    [mailto:centos-bounces at centos.org] On Behalf Of Rudi Ahlers
    Sent: Wednesday, 28 April 2010 11:11 PM
    To: CentOS mailing list
    Subject: [CentOS] how to reroute all ADSL traffic via another
    server on theinternet?

    Hi all,

    Does anyone know, if it's possible to reroute all (i.e. HTTP / FTP /
    DNS / SMTP / POP3 / IMAP / etc) from an ADSL connected machine via
    another server, which is currently hosted with IS and has full
    internet access?


    i.e. Can I setup another machine, on a different public IP than the
    dynamic ADSL IP as default gw? OR do I need todo something on that
    machine to work as a router for such a setup?

    Both servers in this case is CentOS linux, but I'm sure that won't
    make a big difference?
    You could use GRE tunnelling, which is supported by Linux and Cisco
    among others.

    You could set up a GRE tunnel between your two sites, assign a /30 for
    the link, and route most traffic over the GRE interface (Minus the IP
    Address of your remote site - it must be routed via your internet
    connection).

    This will behave as a point-to-point link between your sites.

    Check out the ip(8) command, in particular the ip tunnel commands.

    But, something like this should be a nice start:

    ip tunnel add Tunnel0 mode GRE remote 1.2.3.4

    ifconfig Tunnel0 10.10.10.1 netmask 255.255.255.252

    ip route add 1.2.3.4/32 via 6.7.8.9

    That could work approximately the same as a VPN - but you'll probably also have
    to source-NAT as you route on to internet destinations so the return packets
    will follow the same path back.

    --
    Les Mikesell
    lesmikesell at gmail.com

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