Stephen Bosch wrote:
Dag Richards wrote:
>Stephen Bosch wrote:
Imagine the following scenario:
You have two VPN endpoints. is an BSD system
running isakmpd
and pf, the other is a VPN concentrator from some vendor.
The BSD already has other VPNs set up, all using the same
internal network. Renumbering isn't going to work.
The VPN concentrator operator has an internal addressing
scheme he
insists other endpoints conform to.
The question, then:
Is it even possible to NAT through an encryption
interface? For example:
BSD internal network: 192.168.45.0/24
Network other guy would prefer BSD use: 10.110.40.0/24
Network other guy is using: 10.110.10.0/24
The command might look like this:
nat on $enc_if from 192.168.45.0:network to
10.110.10.0:network -
10.110.40.10
Forgive me if this i) is impossible, ii) is crazy, iii)
the syntax of
the command is wrong.
I'd rather run it past the list than tinker on production
equipment.
Thanks for any help and advice,
-Stephen-

>blind leading the blind here but
>This was recently discussed, and it was pointed out that
>the decision to encrypt happens before the nat-ing.
Correct me if I am wrong, then -- this should work. I
should be able to
set up a NAT rule that will affect encrypted traffic in the
way I want.
Someone mentioned to me that this does work in 3.9. Will it
work in 3.8?
That's what our gear is running.
-Stephen-
Um no, it wont work. the traffic is encrypted you will
no longer be
able to nat it. The original packet is now and encrypted
blob that is
the payload of a new packet with a source of your gateway and
dest their
GW. you can nat the wrapper packet but not the payload.
I have 2x ibm x series somethings for fw's, and 2x hp dl360s for vpn
servers all running 3.9.
Yes it does work! I guess I better hold on to these two boxes I have. Seems
they are the only ones that do! lol
I have
A. clients on each end behind a vpn/pf box
B. enc0 binat from internal client to public IP of other side client
C. /etc/hostname.if alias for the binat IP
D. isakmpd.conf uses public IP (A) for phase 1, and (B internal client nat) for
phase 2
(ip's changed to protect the innocent. No animals were harmed during this test)
Jun 28 13:23:32.881298 (authentic,confidential): SPI 0x84adb14b: 222.222.222.111 111.111.111.111: 222.222.222.222.25247 111.111.111.222.80: S [tcp sum ok] 789729009:789729009(0) win 16384 <mss 1460,nop,nop,K,nop,wscale 0,nop,nop,timestamp 345218535 0(DF) [tos 0x10] (ttl 63, id 29296, len 64) (DF) [tos 0x10] (ttl 63, id 44546, len 84)
Jun 28 13:23:32.882822 (authentic,confidential): SPI 0xcf4b18fb: 111.111.111.111 222.222.222.111: 111.111.111.222.80 222.222.222.222.25247: S [tcp sum ok] 3946347346:3946347346(0) ack 789729010 win 16384 <mss 1460,nop,nop,K,nop,wscale 0,nop,nop,timestamp 1861954054 345218535(DF) (ttl 63, id 35574, len 64) (DF) (ttl 64, id 12842, len 84, bad cksum 0!)
Jun 28 13:23:32.883716 (authentic,confidential): SPI 0x84adb14b: 222.222.222.111 111.111.111.111: 222.222.222.222.25247 111.111.111.222.80: . [tcp sum ok] ack 1 win 17376 <nop,nop,timestamp 345218535 1861954054(DF) [tos 0x10] (ttl 63, id 31269, len 52) (DF) [tos 0x10] (ttl 63, id 34993, len 72)
Jun 28 13:23:37.013444 (authentic,confidential): SPI 0x84adb14b: 222.222.222.111 111.111.111.111: 222.222.222.222.25247 111.111.111.222.80: F [tcp sum ok] 1:1(0) ack 1 win 17376 <nop,nop,timestamp 345218543 1861954054(DF) [tos 0x10] (ttl 63, id 30180, len 52) (DF) [tos 0x10] (ttl 63, id 61997, len 72)
Jun 28 13:23:37.013716 (authentic,confidential): SPI 0xcf4b18fb: 111.111.111.111 222.222.222.111: 111.111.111.222.80 222.222.222.222.25247: . [tcp sum ok] ack 2 win 17376 <nop,nop,timestamp 1861954062 345218543(DF) (ttl 63, id 56710, len 52) (DF) (ttl 64, id 21978, len 72, bad cksum 0!)
Jun 28 13:23:37.013806 (authentic,confidential): SPI 0xcf4b18fb: 111.111.111.111 222.222.222.111: 111.111.111.222.80 222.222.222.222.25247: F [tcp sum ok] 1:1(0) ack 2 win 17376 <nop,nop,timestamp 1861954062 345218543(DF) (ttl 63, id 40038, len 52) (DF) (ttl 64, id 19310, len 72, bad cksum 0!)
Jun 28 13:23:37.014441 (authentic,confidential): SPI 0x84adb14b: 222.222.222.111 111.111.111.111: 222.222.222.222.25247 111.111.111.222.80: . [tcp sum ok] ack 2 win 17375 <nop,nop,timestamp 345218543 1861954062(DF) [tos 0x10] (ttl 63, id 838, len 52) (DF) [tos 0x10] (ttl 63, id 53227, len 72)
Jun 28 13:23:38.749637 (authentic,confidential): SPI 0x84adb14b: 222.222.222.111 111.111.111.111: 222.222.222.222.40612 111.111.111.222.80: S [tcp sum ok] 402874189:402874189(0) win 16384 <mss 1460,nop,nop,K,nop,wscale 0,nop,nop,timestamp 345218547 0(DF) [tos 0x10] (ttl 63, id 9220, len 64) (DF) [tos 0x10] (ttl 63, id 51268, len 84)
Jun 28 13:23:38.749953 (authentic,confidential): SPI 0xcf4b18fb: 111.111.111.111 222.222.222.111: 111.111.111.222.80 222.222.222.222.40612: S [tcp sum ok] 2637765617:2637765617(0) ack 402874190 win 16384 <mss 1460,nop,nop,K,nop,wscale 0,nop,nop,timestamp 1723892848 345218547(DF) (ttl 63, id 64094, len 64) (DF) (ttl 64, id 31080, len 84, bad cksum 0!)
Jun 28 13:23:38.750648 (authentic,confidential): SPI 0x84adb14b: 222.222.222.111 111.111.111.111: 222.222.222.222.40612 111.111.111.222.80: . [tcp sum ok] ack 1 win 17376 <nop,nop,timestamp 345218547 1723892848(DF) [tos 0x10] (ttl 63, id 6907, len 52) (DF) [tos 0x10] (ttl 63, id 62250, len 72)

Roy Morris wrote:
>Stephen Bosch wrote:
Dag Richards wrote:
Stephen Bosch wrote:
Imagine the following scenario:

You have two VPN endpoints. is an BSD system
>running isakmpd
and pf, the other is a VPN concentrator from some vendor.

The BSD already has other VPNs set up, all using the same
internal network. Renumbering isn't going to work.

The VPN concentrator operator has an internal addressing
>scheme he
insists other endpoints conform to.

The question, then:

Is it even possible to NAT through an encryption
>interface? For example:
BSD internal network: 192.168.45.0/24
Network other guy would prefer BSD use: 10.110.40.0/24

Network other guy is using: 10.110.10.0/24

The command might look like this:

nat on $enc_if from 192.168.45.0:network to
>10.110.10.0:network -
10.110.40.10

Forgive me if this i) is impossible, ii) is crazy, iii)
>the syntax of
the command is wrong.

I'd rather run it past the list than tinker on production
>equipment.
Thanks for any help and advice,

-Stephen-
blind leading the blind here but
This was recently discussed, and it was pointed out that
the decision to encrypt happens before the nat-ing.
Correct me if I am wrong, then -- this should work. I
>should be able to
set up a NAT rule that will affect encrypted traffic in the
>way I want.
Someone mentioned to me that this does work in 3.9. Will it
>work in 3.8?
That's what our gear is running.

-Stephen-

>Um no, it wont work. the traffic is encrypted you will
>no longer be
>able to nat it. The original packet is now and encrypted
>blob that is
>the payload of a new packet with a source of your gateway and
>dest their
>GW. you can nat the wrapper packet but not the payload.
>>
>I have 2x ibm x series somethings for fw's, and 2x hp dl360s for vpn
>servers all running 3.9.

Yes it does work! I guess I better hold on to these two boxes I have. Seems
they are the only ones that do! lol

I have
A. clients on each end behind a vpn/pf box
B. enc0 binat from internal client to public IP of other side client
C. /etc/hostname.if alias for the binat IP
D. isakmpd.conf uses public IP (A) for phase 1, and (B internal client nat) for
phase 2

(ip's changed to protect the innocent. No animals were harmed during this test)

Jun 28 13:23:32.881298 (authentic,confidential): SPI 0x84adb14b: 222.222.222.111 111.111.111.111: 222.222.222.222.25247 111.111.111.222.80: S [tcp sum ok] 789729009:789729009(0) win 16384 <mss 1460,nop,nop,K,nop,wscale 0,nop,nop,timestamp 345218535 0(DF) [tos 0x10] (ttl 63, id 29296, len 64) (DF) [tos 0x10] (ttl 63, id 44546, len 84)
Jun 28 13:23:32.882822 (authentic,confidential): SPI 0xcf4b18fb: 111.111.111.111 222.222.222.111: 111.111.111.222.80 222.222.222.222.25247: S [tcp sum ok] 3946347346:3946347346(0) ack 789729010 win 16384 <mss 1460,nop,nop,K,nop,wscale 0,nop,nop,timestamp 1861954054 345218535(DF) (ttl 63, id 35574, len 64) (DF) (ttl 64, id 12842, len 84, bad cksum 0!)
Jun 28 13:23:32.883716 (authentic,confidential): SPI 0x84adb14b: 222.222.222.111 111.111.111.111: 222.222.222.222.25247 111.111.111.222.80: . [tcp sum ok] ack 1 win 17376 <nop,nop,timestamp 345218535 1861954054(DF) [tos 0x10] (ttl 63, id 31269, len 52) (DF) [tos 0x10] (ttl 63, id 34993, len 72)
Jun 28 13:23:37.013444 (authentic,confidential): SPI 0x84adb14b: 222.222.222.111 111.111.111.111: 222.222.222.222.25247 111.111.111.222.80: F [tcp sum ok] 1:1(0) ack 1 win 17376 <nop,nop,timestamp 345218543 1861954054(DF) [tos 0x10] (ttl 63, id 30180, len 52) (DF) [tos 0x10] (ttl 63, id 61997, len 72)
Jun 28 13:23:37.013716 (authentic,confidential): SPI 0xcf4b18fb: 111.111.111.111 222.222.222.111: 111.111.111.222.80 222.222.222.222.25247: . [tcp sum ok] ack 2 win 17376 <nop,nop,timestamp 1861954062 345218543(DF) (ttl 63, id 56710, len 52) (DF) (ttl 64, id 21978, len 72, bad cksum 0!)
Jun 28 13:23:37.013806 (authentic,confidential): SPI 0xcf4b18fb: 111.111.111.111 222.222.222.111: 111.111.111.222.80 222.222.222.222.25247: F [tcp sum ok] 1:1(0) ack 2 win 17376 <nop,nop,timestamp 1861954062 345218543(DF) (ttl 63, id 40038, len 52) (DF) (ttl 64, id 19310, len 72, bad cksum 0!)
Jun 28 13:23:37.014441 (authentic,confidential): SPI 0x84adb14b: 222.222.222.111 111.111.111.111: 222.222.222.222.25247 111.111.111.222.80: . [tcp sum ok] ack 2 win 17375 <nop,nop,timestamp 345218543 1861954062(DF) [tos 0x10] (ttl 63, id 838, len 52) (DF) [tos 0x10] (ttl 63, id 53227, len 72)
Jun 28 13:23:38.749637 (authentic,confidential): SPI 0x84adb14b: 222.222.222.111 111.111.111.111: 222.222.222.222.40612 111.111.111.222.80: S [tcp sum ok] 402874189:402874189(0) win 16384 <mss 1460,nop,nop,K,nop,wscale 0,nop,nop,timestamp 345218547 0(DF) [tos 0x10] (ttl 63, id 9220, len 64) (DF) [tos 0x10] (ttl 63, id 51268, len 84)
Jun 28 13:23:38.749953 (authentic,confidential): SPI 0xcf4b18fb: 111.111.111.111 222.222.222.111: 111.111.111.222.80 222.222.222.222.40612: S [tcp sum ok] 2637765617:2637765617(0) ack 402874190 win 16384 <mss 1460,nop,nop,K,nop,wscale 0,nop,nop,timestamp 1723892848 345218547(DF) (ttl 63, id 64094, len 64) (DF) (ttl 64, id 31080, len 84, bad cksum 0!)
Jun 28 13:23:38.750648 (authentic,confidential): SPI 0x84adb14b: 222.222.222.111 111.111.111.111: 222.222.222.222.40612 111.111.111.222.80: . [tcp sum ok] ack 1 win 17376 <nop,nop,timestamp 345218547 1723892848(DF) [tos 0x10] (ttl 63, id 6907, len 52) (DF) [tos 0x10] (ttl 63, id 62250, len 72)

K I thought you were trying to change the internal client addr to an
arbitrary third addr oh that is what you did.

I'll be dipped. So I better go back and re-read he earlier discussion
as I clearly did not understand it.

Roy Morris wrote:
>Stephen Bosch wrote:
Dag Richards wrote:
Stephen Bosch wrote:
Imagine the following scenario:

You have two VPN endpoints. is an BSD system
>running isakmpd
and pf, the other is a VPN concentrator from some vendor.

The BSD already has other VPNs set up, all using the same
internal network. Renumbering isn't going to work.

The VPN concentrator operator has an internal addressing
>scheme he
insists other endpoints conform to.

The question, then:

Is it even possible to NAT through an encryption
>interface? For example:
BSD internal network: 192.168.45.0/24
Network other guy would prefer BSD use: 10.110.40.0/24

Network other guy is using: 10.110.10.0/24

The command might look like this:

nat on $enc_if from 192.168.45.0:network to
>10.110.10.0:network -
10.110.40.10

Forgive me if this i) is impossible, ii) is crazy, iii)
>the syntax of
the command is wrong.

I'd rather run it past the list than tinker on production
>equipment.
Thanks for any help and advice,

-Stephen-
blind leading the blind here but
This was recently discussed, and it was pointed out that
the decision to encrypt happens before the nat-ing.
Correct me if I am wrong, then -- this should work. I
>should be able to
set up a NAT rule that will affect encrypted traffic in the
>way I want.
Someone mentioned to me that this does work in 3.9. Will it
>work in 3.8?
That's what our gear is running.

-Stephen-

>Um no, it wont work. the traffic is encrypted you will
>no longer be
>able to nat it. The original packet is now and encrypted
>blob that is
>the payload of a new packet with a source of your gateway and
>dest their
>GW. you can nat the wrapper packet but not the payload.
>>
>I have 2x ibm x series somethings for fw's, and 2x hp dl360s for vpn
>servers all running 3.9.

Just for clarity, I made this diagram, so we are all talking about the
same thing.

Roy Morris wrote:
>Stephen Bosch wrote:
>Dag Richards wrote:
>Um no, it wont work. the traffic is encrypted you will
>no longer be
>able to nat it. The original packet is now and encrypted
>blob that is
>the payload of a new packet with a source of your gateway and
>dest their
>GW. you can nat the wrapper packet but not the payload.
>>
>I have 2x ibm x series somethings for fw's, and 2x hp dl360s for vpn
>servers all running 3.9.

Yes it does work! I guess I better hold on to these two boxes I have. Seems
they are the only ones that do! lol

I have
A. clients on each end behind a vpn/pf box
B. enc0 binat from internal client to public IP of other side client
C. /etc/hostname.if alias for the binat IP
D. isakmpd.conf uses public IP (A) for phase 1, and (B internal client nat) for
phase 2

Just to be clear here, I'll try and explain in greater detail.

I have a host with IP 10.225.10.10.

The remote network is 10.40.10.0/24.

The remote network insists that my internal host be on the 10.50.10.0/24
network. In a perfect world, I'd just renumber on my end, or get him to
accept my internal network, but he won't do that. So I have to NAT my
internal network to a private IP that fits his addressing scheme.

I need to NAT 10.225.10.10 so that it will appear as 10.50.10.10 in the
remote peer's tunnel.

If NAT happens before encryption, then this should be possible.

If NAT happens after encryption, I have a problem, and an alias doesn't
look like it's going to help.

Feedback?
-Stephen-

Hi, Roy:

Roy Morris wrote:

Yes it does work! I guess I better hold on to these two boxes I have. Seems
they are the only ones that do! lol

I have
A. clients on each end behind a vpn/pf box
B. enc0 binat from internal client to public IP of other side client
C. /etc/hostname.if alias for the binat IP
D. isakmpd.conf uses public IP (A) for phase 1, and (B internal client nat) for
phase 2

I've had a closer look at this

In my case, the other peer expects a private IP on my internal network.
Your directions involve an alias. Do I need this alias?

Can I not just nat on the encryption interface like so?

nat on $enc_if from $internal_ip to $remote_internal_ip -
$private_nat_address?

This is really confusing me.
-Stephen-

Wed, 28 Jun 2006, Stephen Bosch wrote:

Hi, Roy:

Roy Morris wrote:
>
>Yes it does work! I guess I better hold on to these two boxes I have. Seems
>they are the only ones that do! lol
>I have
>A. clients on each end behind a vpn/pf box
>B. enc0 binat from internal client to public IP of other side client
>C. /etc/hostname.if alias for the binat IP
>D. isakmpd.conf uses public IP (A) for phase 1, and (B internal client nat)
>for phase 2
>
I've had a closer look at this

In my case, the other peer expects a private IP on my internal network. Your
directions involve an alias. Do I need this alias?

Can I not just nat on the encryption interface like so?

nat on $enc_if from $internal_ip to $remote_internal_ip -
$private_nat_address?

This is really confusing me.

-Stephen-
--

If you do nat on $enc_if your incoming packets will not match an existing
IPSEC flow and will never get routed to your enc0 interface in the first place.

man ipsec shows a flow diagram of how packets move in the kernel

-Matt-