NAT and STatic IP addressing with ip

NAT and STatic IP addressing with ip

Post by B'ichel » Wed, 12 Mar 2003 19:01:34



Snet at SBCglobal.net gave me a network block of 8 addresses. these
are as follows:
69.0.3.136-69.0.3.143 with my gateway address as 69.0.3.142 Now
according to the letter they sent me. and this is the pertient parts
being quoted:

We will provision the last usable IP address as the WAN IP address. In
order to utilize the first five static IP addresses in your subnet,
you will have to configure "IP Mapping" on your router. Each of the
routers which we provide is configured to utilize Network Address
Translation (NAT) and Private, non-routable IP address on the Ethernet
side of the router. IP Mapping maps a public, routable IP address to a
private non-routable IP address on the Ethernet side of the Router.

Now heres the Crunch. I am using a Linux box for Masquarading some
in-house addresses AND I also want to be able to use some of the 5
STATIC ip addresses for several systems. I installed iproute2 and its
ip program and did this in my rc.firewall:
/sbin/ip route add nat 69.0.3.137 via 192.168.10.2
From outside of the LAN I cannot telnet to 69.0.3.137. I can't Ping it
either. So how do I allow my box to allow all connections to
69.0.3.137 to get through. while still blocking or allowing on a port
by port basis for the other machines?
        Before anyone suggests I buy a router. all of the ones I seen
are for 10base-t. I have 10base-2! for the inside line and the only
10base-t is for the ADSL Modem. Masquarading works fine. but I want to
use those 5 other Static IP address they gave me too!
        Is there a Ascii Howto for NAT or iproute2? I rather not go
with Ghostscript right now as my Inkjet is a ink-pig and my Dot-matrix
(Panasonic kx-p1180) will take eons to print a monster book in Bit
mapped graphics.

--
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(I keep hearing RTFM, but I'm not sure where TFM is).
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NAT and STatic IP addressing with ip

Post by JamesKir » Sat, 22 Mar 2003 02:42:24



> Now heres the Crunch. I am using a Linux box for Masquarading some
> in-house addresses AND I also want to be able to use some of the 5
> STATIC ip addresses for several systems. I installed iproute2 and its
> ip program and did this in my rc.firewall:
> /sbin/ip route add nat 69.0.3.137 via 192.168.10.2
> From outside of the LAN I cannot telnet to 69.0.3.137. I can't Ping it
> either. So how do I allow my box to allow all connections to
> 69.0.3.137 to get through. while still blocking or allowing on a port
> by port basis for the other machines?

hi! whats your status? did you somehow solve the problem?
i have the same problem and also appricate any help to this subject..

cheers,
james

 
 
 

NAT and STatic IP addressing with ip

Post by B'ichel » Sat, 22 Mar 2003 15:02:24



> hi! whats your status? did you somehow solve the problem?
> i have the same problem and also appricate any help to this subject..

        No, I am still looking for help on this. No one wants or seems
to know or want to give me a clue.

--
A tagline from Comp.os.Linux.Advocacy:
(I keep hearing RTFM, but I'm not sure where TFM is).
                From the Desk of the Sysop of:
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Telephone 860-738-7176 300-33.6kbps
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NAT and STatic IP addressing with ip

Post by jack » Sat, 22 Mar 2003 17:54:58



>    No, I am still looking for help on this. No one wants or seems
> to know or want to give me a clue.

Hi there!,

This is just too simple. - Just don't make things too complicated:

Configure Your box to do masquerading on Your private internal IPs
as You normally would, and apply Your firewall rules. Then, insert
rules that will prevent Your public IPs from being masqueraded, but
that will simply redirect these packets from/to Your dedicated ser-
vers (You can even specify port ranges).

That should be it, if I got Your OP correctly.

There's a Networking- and, IIRC, an IP-Masquerading-HowTo which will
give You more insight in this issue.

Hope this helps, Jack.

--
----------------------------------------------------------------------
My personal reading of the string "MicroSoft" expands to "NanoWeak"...

 
 
 

NAT and STatic IP addressing with ip

Post by B'ichel » Sun, 23 Mar 2003 01:03:06



> as You normally would, and apply Your firewall rules. Then, insert
> rules that will prevent Your public IPs from being masqueraded, but
> that will simply redirect these packets from/to Your dedicated ser-
> vers (You can even specify port ranges).

How do I do that? I need examples here. and yes, I am reading the
networking howto and the ip-masquarading-howto.
Quote:> That should be it, if I got Your OP correctly.
> There's a Networking- and, IIRC, an IP-Masquerading-HowTo which will
> give You more insight in this issue.

I followed the instructions from the Networkng HOWTO and downloaded
iproute2. I compiled it (no errors). but this line does not work at
all
/sbin/ip route add nat 69.0.3.137 via 192.168.10.2
that was to set up any packets for 69.0.3.137 to go to internal
machine 192.168.10.2
        It does NOT work! Is iproute2 for really 2.2.x or 2.4.x or
2.0.x? if either 2.4.x or 2.0.x then how do I do it in 2.2.x?
        RElated to this. what do I need to do to make sure my finished
work-units get back to setiathome? My status has not been updated in
days and I know at least two work units have supposibly gone out. The
boxes are headless so I cannot directly see the status reports. Has
anyone else done setiathome behind masquarading?

--
A tagline from Comp.os.Linux.Advocacy:
(I keep hearing RTFM, but I'm not sure where TFM is).
                From the Desk of the Sysop of:
Planet Maca's Opus, a Free open BBS system.
Telephone 860-738-7176 300-33.6kbps
Telnet://pinkrose.dhis.org. Open 24/7!
                        The New Cnews maintainer
                                B'ichela

 
 
 

NAT and STatic IP addressing with ip

Post by JamesKir » Sun, 23 Mar 2003 20:48:54



> No, I am still looking for help on this. No one wants or seems
> to know or want to give me a clue.

i was also looking for a solution the last few days. and after searching and
searching over and over in the net i found a interesting site (again):

www.shorewall.net

"again" because i already use shorewall as my firewall but never saw our
kind of configuration in the docs.

see the "Static NAT" or "his" configuration
(http://www.shorewall.net/myfiles.htm).

i still was not able to test the whole thing but i look forward to get the
whole thing work the way i want.

just FYI. i use version 1.2.12 (of shorewall) on my router/firewall and just
installed v1.3.14 on my testssytem (and not the new 1.4 version) because i
use debian.. and there is only v1.3.14 of it available as deb package...
(you can get to the "old" docs by clicking the link on top the "home"-site)

please let me know if you got your thing work.. i am not sure, if i can do
anything this weekend but if so i will inform you about any progress.

thx and good luck

james

 
 
 

NAT and STatic IP addressing with ip

Post by B'ichel » Mon, 24 Mar 2003 01:01:57



> please let me know if you got your thing work.. i am not sure, if i can do
> anything this weekend but if so i will inform you about any progress.

        I will look at that. today more than likely. and yes, let me
know your  results too.

--
A tagline from Comp.os.Linux.Advocacy:
(I keep hearing RTFM, but I'm not sure where TFM is).
                From the Desk of the Sysop of:
Planet Maca's Opus, a Free open BBS system.
Telephone 860-738-7176 300-33.6kbps
Telnet://pinkrose.dhis.org. Open 24/7!
                        The New Cnews maintainer
                                B'ichela

 
 
 

NAT and STatic IP addressing with ip

Post by jack » Mon, 24 Mar 2003 18:49:28



> How do I do that? I need examples here. and yes, I am reading the
> networking howto and the ip-masquarading-howto.
> I followed the instructions from the Networkng HOWTO and downloaded
> iproute2. I compiled it (no errors). but this line does not work at
> all
> /sbin/ip route add nat 69.0.3.137 via 192.168.10.2
> that was to set up any packets for 69.0.3.137 to go to internal
> machine 192.168.10.2

No need for that:

Just add two routes like so:

"route add -net 69.0.3.136 netmask 255.255.255.248",
perhaps You need to specify Your device as well. This will tell Your
router to forward all traffic that comes in for those addresses.

I didn't get Your exact configuration from Your OP... - What is the
IP of the remote gateway? - If it is in 69.0.3.[137..142], You will
need to add one route to this host,
"route add -host $REMOTE_GW_IP", plus, of course, set the default
route there, "route add default gw $REMOTE_GW_IP".

Make sure that, on Your clients with these public IPs, Your linux
router is set as the [default] gw. And, review any iptables rules or
the like so that packets from one of the public IP clients will _not_
be masqueraded or anything. THIS is, in fact, the key point.

Quote:>    RElated to this. what do I need to do to make sure my finished
> work-units get back to setiathome? My status has not been updated in
> days and I know at least two work units have supposibly gone out. The
> boxes are headless so I cannot directly see the status reports. Has
> anyone else done setiathome behind masquarading?

Sorry, but for SETI I cannot say anything... - Never used that.

Cheers, Jack.

--
----------------------------------------------------------------------
My personal reading of the string "MicroSoft" expands to "NanoWeak"...

 
 
 

NAT and STatic IP addressing with ip

Post by B'ichel » Tue, 25 Mar 2003 01:02:18



> No need for that:

> Just add two routes like so:

> "route add -net 69.0.3.136 netmask 255.255.255.248",
> perhaps You need to specify Your device as well. This will tell Your
> router to forward all traffic that comes in for those addresses.

        Ok heres the scoop
The Gateway box (right now the firewall) is 69.0.3.142
First address (network Number) this is from the SBC global letter
69.0.3.136
Broadcast address 69.0.3.143
Oh.... Wait a sec, not seeing forest through the trees. Being this is
the Gateway. would a slight change to my route table fix this?

Kernel IP routing table
Destination     Gateway         Genmask         Flags Metric Ref    Use Iface
69.0.3.254.adsl *               255.255.255.255 UH    0      0        0 ppp0
localnet        *               255.255.255.0   U     0      0        0 eth0
loopback        *               255.0.0.0       U     0      0        0 lo
default         69.0.3.254.adsl 0.0.0.0         UG    0      0        0 ppp0

If you understand you. Instad of doing things like this in ifconfig:
(this is the inhouse card. not the pppoe connected card).
eth0      Link encap:Ethernet  HWaddr 00:C0:26:E9:FD:35  
          inet addr:192.168.10.1  Bcast:192.168.10.255  Mask:255.255.255.0
          UP BROADCAST RUNNING MULTICAST  MTU:1500  Metric:1
          RX packets:95950 errors:0 dropped:0 overruns:0 frame:0
          TX packets:112888 errors:0 dropped:0 overruns:0 carrier:0
          collisions:7 txqueuelen:100
          RX bytes:7858495 (7.4 Mb)  TX bytes:60154451 (57.3 Mb)
          Interrupt:10 Base address:0xff80
In my /etc/rc.d/rc.inet1 I have it as so.
IPADDR="192.168.10.1" # REPLACE with YOUR IP address!
NETMASK="255.255.255.0"       # REPLACE with YOUR netmask!
NETWORK="192.168.10.0"        # REPLACE with YOUR network address!
BROADCAST="192.168.10.255"    # REPLACE with YOUR broadcast address, if you
                        # have one. If not, leave blank and edit below.
GATEWAY=""    # REPLACE with YOUR gateway address!

Therefore if I replace the above with my sbcglobal static IP address
info  then my local net will work? therefore
IPADDR="69.0.3.142"
NETWORK="69.0.3.136"
NETMASK="255.255.255.248"
BROADCAST="69.0.3.143"

Is that really all I need to do? If so, why is Snet SBCGLOBAL net
telling me to do NAT? and can a remote person ping say one of the
machines behind the gateway. say I want to allow ftp to 69.0.3.137. (a
welcome access, not cracked). even if they are connecting outside of
my lan? How does my gateway know to handle a remote access to a
machine behind the gateway? or is there additional work required?
        OTOH, what if I DO need to Masquarade some boxes, say I had 9
boxes,  more than the number of usuable IP addresss by 3. can I do
both?

--
A tagline from Comp.os.Linux.Advocacy:
(I keep hearing RTFM, but I'm not sure where TFM is).
                From the Desk of the Sysop of:
Planet Maca's Opus, a Free open BBS system.
Telephone 860-738-7176 300-33.6kbps
Telnet://pinkrose.dhis.org. Open 24/7!
                        The New Cnews maintainer
                                B'ichela

 
 
 

NAT and STatic IP addressing with ip

Post by jack » Tue, 25 Mar 2003 06:09:27



>    Ok heres the scoop
> The Gateway box (right now the firewall) is 69.0.3.142
> First address (network Number) this is from the SBC global letter
> 69.0.3.136
> Broadcast address 69.0.3.143

Ok, that is fairly obvious. - You should be able to determine that for
Yourself. If not, re-read the Networking-HowTo.

Quote:> Oh.... Wait a sec, not seeing forest through the trees. Being this is
> the Gateway. would a slight change to my route table fix this?

> Kernel IP routing table
> Destination     Gateway         Genmask         Flags Metric Ref    Use Iface
> 69.0.3.254.adsl *               255.255.255.255 UH    0      0        0 ppp0
> localnet        *               255.255.255.0   U     0      0        0 eth0
> loopback        *               255.0.0.0       U     0      0        0 lo
> default         69.0.3.254.adsl 0.0.0.0         UG    0      0        0 ppp0

Now, just for the fun of it, try to think about how Your router will
forward packets to a destination IP of 69.0.3.136/29...? - It won't,
since it has no route to that subnet.

Add the rules I recommended.

Quote:> If you understand you. Instad of doing things like this in ifconfig:

I certainly try to understand myself... ;)

Quote:> (this is the inhouse card. not the pppoe connected card).
> eth0      Link encap:Ethernet  HWaddr 00:C0:26:E9:FD:35  
>           inet addr:192.168.10.1  Bcast:192.168.10.255  Mask:255.255.255.0
>           UP BROADCAST RUNNING MULTICAST  MTU:1500  Metric:1
>           RX packets:95950 errors:0 dropped:0 overruns:0 frame:0
>           TX packets:112888 errors:0 dropped:0 overruns:0 carrier:0
>           collisions:7 txqueuelen:100
>           RX bytes:7858495 (7.4 Mb)  TX bytes:60154451 (57.3 Mb)
>           Interrupt:10 Base address:0xff80
> In my /etc/rc.d/rc.inet1 I have it as so.
> IPADDR="192.168.10.1"    # REPLACE with YOUR IP address!
> NETMASK="255.255.255.0"  # REPLACE with YOUR netmask!
> NETWORK="192.168.10.0"   # REPLACE with YOUR network address!
> BROADCAST="192.168.10.255"       # REPLACE with YOUR broadcast address, if you
>                    # have one. If not, leave blank and edit below.
> GATEWAY=""       # REPLACE with YOUR gateway address!

> Therefore if I replace the above with my sbcglobal static IP address
> info  then my local net will work? therefore
> IPADDR="69.0.3.142"
> NETWORK="69.0.3.136"
> NETMASK="255.255.255.248"
> BROADCAST="69.0.3.143"

No. - You cannot "replace" this, but You have to additionally specify
this. I may assume that You have two NICs in Your router. One that
connects to Your LAN (192.168.10.1), and one that serves the ADSL line
as ppp0 (69.0.3.142).

So if You're talking about "ifconfig", if You issue this command with-
out arguments, it will show eth0, lo, and ppp0. It will also show eth1,
but the settings shown will never be used. (Eventually, ppp0 replaces
eth1 in this context.)

Quote:> Is that really all I need to do? If so, why is Snet SBCGLOBAL net
> telling me to do NAT? and can a remote person ping say one of the
> machines behind the gateway. say I want to allow ftp to 69.0.3.137. (a
> welcome access, not cracked). even if they are connecting outside of
> my lan? How does my gateway know to handle a remote access to a
> machine behind the gateway? or is there additional work required?

No. - Your gw will know how to handle such request because You tell it
how to handle that in its routing table. Again, refer to the "route"
commands I gave You. That is, tell Your router that, besides the LAN
(192.168.10.0/24?), there is a range of IPs, hence a subnet, that shall
also be addressed via eth0, namely 69.0.3.136/29. Simple, isn't it...?

Quote:>    OTOH, what if I DO need to Masquarade some boxes, say I had 9
> boxes,  more than the number of usuable IP addresss by 3. can I do
> both?

"By 3"...? - Anyways: Of course You can do that, and You would know if
You had read (and understood) the Networking- and the IP-Masquerading-
HowTos. But here You go:

On all boxes that have one of Your public IPs, set a route to the LAN
via their respective NIC, but add the default route through Your gw,
i. e. 192.168.10.1. Do _not_ use the gw public IP 69.0.3.142.

On all other clients on the LAN that have private IP addresses in the
192.168.10.0/24 range, add the default gateway. Optionally, You can
add the 69.0.3.136/29 net via that same interface.

Finally, on the router itself, make sure to MASQUERADE all connections
that come from 192.168.10.0/24, but _not_ to MASQ connections from
69.0.3.136/29.

This is it. It may seem that it was a long way for You to get here,
but, in fact, this is as simple a setup as it was before. You only
added one address space that will be trated differently, which is not
uncommon.

And, again, I recommend reading the HowTos mentioned above. - And, of
course, understanding them.

Cheers, Jack.

--
----------------------------------------------------------------------
My personal reading of the string "MicroSoft" expands to "NanoWeak"...

 
 
 

NAT and STatic IP addressing with ip

Post by B'ichel » Tue, 25 Mar 2003 15:03:06



> And, again, I recommend reading the HowTos mentioned above. - And, of
> course, understanding them.

        I will look at a few things.  1.
bridging+firewall-HOWTO
already reading
Ip-Masquarading HOWTO
and the general Networking-HOWTO. Not as informative as the old
Net3-HOWTO but  thats thats because its a LinuxDoc howto, came with my
Slackware distro.
        As for which NIC is what, yes,  eth0 is my inhouse segment of
the lan of 192.168.10.0, and  via Roaring Penquin PPPoe  my eth1 NIC
feeds my ADSL modem. I installed the IP-alias  system of 2.2.20  as I
knew that  I may need   the same inhouse network to feed  some boxes
to be Masquaraded, and some that are true Static IP machines.
        I also  want to try to print this thread so I can  review it.

--
A tagline from Comp.os.Linux.Advocacy:
(I keep hearing RTFM, but I'm not sure where TFM is).
                From the Desk of the Sysop of:
Planet Maca's Opus, a Free open BBS system.
Telephone 860-738-7176 300-33.6kbps
Telnet://pinkrose.dhis.org. Open 24/7!
                        The New Cnews maintainer
                                B'ichela

 
 
 

NAT and STatic IP addressing with ip

Post by jack » Tue, 25 Mar 2003 16:40:40



>    I also  want to try to print this thread so I can  review it.

So I understand that things are working now...? - Good.

If not, feel free to ask again. But I'm sure that by now You will find
most of the answers Yourself. Congratulations.

Cheers, Jack.

--
----------------------------------------------------------------------
My personal reading of the string "MicroSoft" expands to "NanoWeak"...

 
 
 

NAT and STatic IP addressing with ip

Post by B'ichel » Tue, 25 Mar 2003 23:02:18




>>        I also  want to try to print this thread so I can  review it.

> So I understand that things are working now...? - Good.

No, but My head is hurting. and if what I think is going to happen may
break my firewall/gateway box which is running Synchronet 3.10k. Since
it is not a high enough priority to mess up my bbs. I am going to hold
off a wee bit longer. But I did print the thread and I am browsing it.
Quote:

> If not, feel free to ask again. But I'm sure that by now You will find
> most of the answers Yourself. Congratulations.

        Well, The original reason was that I wanted to use my block of
8 static IP addresses so I could spread my bbs system among several
boxes. for example.
1. box for nntp
2. box for sendmail
3. box for ftp
4. box for setiathome

I can technically use port forwarding on most of these with what I
have now. I have a working Masquarading system.
        I tested portforwarding and that works well.

--
A tagline from Comp.os.Linux.Advocacy:
(I keep hearing RTFM, but I'm not sure where TFM is).
                From the Desk of the Sysop of:
Planet Maca's Opus, a Free open BBS system.
Telephone 860-738-7176 300-33.6kbps
Telnet://pinkrose.dhis.org. Open 24/7!
                        The New Cnews maintainer
                                B'ichela

 
 
 

NAT and STatic IP addressing with ip

Post by B'ichel » Fri, 28 Mar 2003 07:02:45



> So I understand that things are working now...? - Good.

> If not, feel free to ask again. But I'm sure that by now You will find
> most of the answers Yourself. Congratulations.

        Just today I decided to give it another go. I realized that I
had to fuss with Ipchains. Now it works! and I can telnet to a machine
behind my firewall that has a static IP address, Likewise the machine
reports its real static IP address to others outside the firewall.
Heres the IPchains ruleset that works for me. its Kinda of an open
door right now but it works, that will require some more rules.
working on it. Also my bbs is not affected and is working fine on the
firewall.

target     prot opt     source                destination ports
MASQ       all  ------  192.168.10.0/24          anywhere n/a
ACCEPT     all  ------  69.0.3.136/29            anywhere n/a
ACCEPT     all  ------  anywhere                 69.0.3.136/29  n/a
Chain output (policy ACCEPT):
I also used the ip-alias system to allow me to support both networks
via eth0. Heres the output:

eth0      Link encap:Ethernet  HWaddr 00:C0:26:E9:FD:35  
          inet addr:192.168.10.1  Bcast:192.168.10.255  Mask:255.255.255.0
          UP BROADCAST RUNNING MULTICAST  MTU:1500  Metric:1
          RX packets:11183 errors:0 dropped:0 overruns:0 frame:0
          TX packets:13855 errors:0 dropped:0 overruns:0 carrier:0
          collisions:1 txqueuelen:100
          RX bytes:905238 (884.0 Kb)  TX bytes:7130777 (6.8 Mb)
          Interrupt:10 Base address:0xff80

eth0:0    Link encap:Ethernet  HWaddr 00:C0:26:E9:FD:35  
          inet addr:69.0.3.142  Bcast:69.0.3.143  Mask:255.255.255.248
          UP BROADCAST RUNNING MULTICAST  MTU:1500  Metric:1
          Interrupt:10 Base address:0xff80

        Now that I got it working, what am I going to do with it ;)

--
A tagline from Comp.os.Linux.Advocacy:
(I keep hearing RTFM, but I'm not sure where TFM is).
                From the Desk of the Sysop of:
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1. Q: Multiple IP addresses and (Static) NAT?

I'm trying to connect two networks via a Linux firewall. On one side
(Net B) all incoming connections require individual IP addresses within
a particular range.

Something like:
   PC's In the range 10.1.2.10 to 10.1.2.20   (Net A)
   (Net A connects to a Firewall side 1)
 Firewall: side 1 (10.1.2.254)------(192.168.1.254) side 2
   (Firewall connects to Net B)
   Server on a corporate network 140.2.200.100 (Net B)

With the router purely forwarding I can connect to the server and
finger shows that I have connected from 10.1.2.10 (or whatever).

However as Net A uses the same class A address as is also used on Net B,
the router is required to translate all Net A addresses to the range
192.168.1.1 to .253

Unfortunately masquerading to a single IP address, does not offer a
solution, as security on the server necessitates each incoming
connection has a unique IP address. Hence PCs 10.1.2.10 to 20 need to
appear as 192.168.1.10 to 20 (i.e. converting the first three octects).

By searching, reading FAQs and loads of info, the answer appears to be
static NAT tables. Unfortunately there seems to be little practical
examples.

As some of the information refers to ipchains & ip, I have upgraded
the kernel to 2.2.10.

Could anyone suggest further reading perhaps a HOWTO? Or could anyone
who has built a Static NAT router tell me what commands they have used
to setup the tables?

TIA
Chris

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