Snat

Contents

These scenarios show how to configure SNAT (Source Network Address Translation) on OSDx.

Test SNAT

Description

In this scenario, DUT0 modifies the source address of outgoing packets generated at the LAN side. The address is translated to a custom one: 10.0.0.1.

Scenario

Step 1: Set the following configuration in DUT0:

set interfaces ethernet eth0 address 192.168.100.1/24
set interfaces ethernet eth1 address 10.0.0.2/24
set interfaces ethernet eth1 traffic nat source rule 1 selector SEL
set traffic selector SEL rule 1 protocol tcp,udp
set interfaces ethernet eth1 traffic nat source rule 1 address 10.0.0.2

Step 2: Set the following configuration in DUT1:

set interfaces ethernet eth0 address 10.0.0.22/24

Step 3: Set the following configuration in DUT2:

set interfaces ethernet eth0 address 192.168.100.2/24
set protocols static route 0.0.0.0/0 next-hop 192.168.100.1

Step 4: Ping IP address 192.168.100.2 from DUT0:

admin@DUT0$ ping 192.168.100.2 count 1 size 56 timeout 1

Show output

PING 192.168.100.2 (192.168.100.2) 56(84) bytes of data.
64 bytes from 192.168.100.2: icmp_seq=1 ttl=64 time=0.686 ms

--- 192.168.100.2 ping statistics ---
1 packets transmitted, 1 received, 0% packet loss, time 0ms
rtt min/avg/max/mdev = 0.686/0.686/0.686/0.000 ms

Step 5: Ping IP address 10.0.0.22 from DUT0:

admin@DUT0$ ping 10.0.0.22 count 1 size 56 timeout 1

Show output

PING 10.0.0.22 (10.0.0.22) 56(84) bytes of data.
64 bytes from 10.0.0.22: icmp_seq=1 ttl=64 time=0.520 ms

--- 10.0.0.22 ping statistics ---
1 packets transmitted, 1 received, 0% packet loss, time 0ms
rtt min/avg/max/mdev = 0.520/0.520/0.520/0.000 ms

Step 6: Initiate a tcp connection from DUT2 to DUT1 and try to send some messages between both endpoints

admin@DUT1$ monitor test connection server 8080 tcp
admin@DUT2$ monitor test connection client 10.0.0.22 8080 tcp

Step 7: Initiate a udp connection from DUT2 to DUT1 and try to send some messages between both endpoints

admin@DUT1$ monitor test connection server 5050 udp
admin@DUT2$ monitor test connection client 10.0.0.22 5050 udp

Step 8: Run command system conntrack show nat at DUT0 and check if output contains the following tokens:

src=192.168.100.2 dst=10.0.0.22
src=10.0.0.22 dst=10.0.0.2

Show output

icmp     1 24 src=192.168.100.1 dst=192.168.100.2 type=8 code=0 id=85 packets=1 bytes=84 src=192.168.100.2 dst=192.168.100.1 type=0 code=0 id=85 packets=1 bytes=84 mark=0 use=1
udp      17 src=192.168.100.2 dst=10.0.0.22 sport=36153 dport=5050 packets=5 bytes=240 src=10.0.0.22 dst=10.0.0.2 sport=5050 dport=36153 packets=5 bytes=240 [OFFLOAD, packets=3 bytes=144 packets=4 bytes=192] mark=0 use=2
icmp     1 24 src=10.0.0.2 dst=10.0.0.22 type=8 code=0 id=86 packets=1 bytes=84 src=10.0.0.22 dst=10.0.0.2 type=0 code=0 id=86 packets=1 bytes=84 mark=0 use=1
tcp      6 17 TIME_WAIT src=192.168.100.2 dst=10.0.0.22 sport=41076 dport=8080 packets=14 bytes=836 src=10.0.0.22 dst=10.0.0.2 sport=8080 dport=41076 packets=13 bytes=784 [ASSURED] mark=0 use=1
conntrack v1.4.5 (conntrack-tools): 4 flow entries have been shown.

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Test SNAT Masquerade

Description

This scenario is similar to the previous one, but when masquerade is specified, the route uses the IP address of the outgoing interface. Therefore, masquerading should be configured if the outgoing interface uses a dynamic IP address.

Scenario

Step 1: Set the following configuration in DUT0:

set interfaces ethernet eth0 address 192.168.100.1/24
set interfaces ethernet eth1 address 10.0.0.2/24
set interfaces ethernet eth1 traffic nat source rule 1 selector SEL
set traffic selector SEL rule 1 protocol tcp,udp
set interfaces ethernet eth1 traffic nat source rule 1 address masquerade

Step 2: Set the following configuration in DUT1:

set interfaces ethernet eth0 address 10.0.0.22/24

Step 3: Set the following configuration in DUT2:

set interfaces ethernet eth0 address 192.168.100.2/24
set protocols static route 0.0.0.0/0 next-hop 192.168.100.1

Step 4: Ping IP address 192.168.100.2 from DUT0:

admin@DUT0$ ping 192.168.100.2 count 1 size 56 timeout 1

Show output

PING 192.168.100.2 (192.168.100.2) 56(84) bytes of data.
64 bytes from 192.168.100.2: icmp_seq=1 ttl=64 time=0.462 ms

--- 192.168.100.2 ping statistics ---
1 packets transmitted, 1 received, 0% packet loss, time 0ms
rtt min/avg/max/mdev = 0.462/0.462/0.462/0.000 ms

Step 5: Ping IP address 10.0.0.22 from DUT0:

admin@DUT0$ ping 10.0.0.22 count 1 size 56 timeout 1

Show output

PING 10.0.0.22 (10.0.0.22) 56(84) bytes of data.
64 bytes from 10.0.0.22: icmp_seq=1 ttl=64 time=0.548 ms

--- 10.0.0.22 ping statistics ---
1 packets transmitted, 1 received, 0% packet loss, time 0ms
rtt min/avg/max/mdev = 0.548/0.548/0.548/0.000 ms

Step 6: Initiate a tcp connection from DUT2 to DUT1 and try to send some messages between both endpoints

admin@DUT1$ monitor test connection server 8080 tcp
admin@DUT2$ monitor test connection client 10.0.0.22 8080 tcp

Step 7: Initiate a udp connection from DUT2 to DUT1 and try to send some messages between both endpoints

admin@DUT1$ monitor test connection server 5050 udp
admin@DUT2$ monitor test connection client 10.0.0.22 5050 udp

Step 8: Run command system conntrack show nat at DUT0 and check if output contains the following tokens:

src=192.168.100.2 dst=10.0.0.22
src=10.0.0.22 dst=10.0.0.2

Show output

icmp     1 24 src=10.0.0.2 dst=10.0.0.22 type=8 code=0 id=88 packets=1 bytes=84 src=10.0.0.22 dst=10.0.0.2 type=0 code=0 id=88 packets=1 bytes=84 mark=0 use=1
tcp      6 17 TIME_WAIT src=192.168.100.2 dst=10.0.0.22 sport=48398 dport=8080 packets=14 bytes=836 src=10.0.0.22 dst=10.0.0.2 sport=8080 dport=48398 packets=13 bytes=784 [ASSURED] mark=0 use=1
icmp     1 24 src=192.168.100.1 dst=192.168.100.2 type=8 code=0 id=87 packets=1 bytes=84 src=192.168.100.2 dst=192.168.100.1 type=0 code=0 id=87 packets=1 bytes=84 mark=0 use=1
udp      17 src=192.168.100.2 dst=10.0.0.22 sport=41473 dport=5050 packets=5 bytes=240 src=10.0.0.22 dst=10.0.0.2 sport=5050 dport=41473 packets=5 bytes=240 [OFFLOAD, packets=3 bytes=144 packets=4 bytes=192] mark=0 use=2
conntrack v1.4.5 (conntrack-tools): 4 flow entries have been shown.

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Test SNAT Port Pool

Description

In this scenario, the translation is performed using masquerade with a pool of 3 ports. If at any time there are 3 active connections, the next one will be rejected.

Scenario

Step 1: Set the following configuration in DUT0:

set interfaces ethernet eth0 address 192.168.100.1/24
set interfaces ethernet eth1 address 10.0.0.2/24
set interfaces ethernet eth1 traffic nat source rule 1 selector SEL
set traffic selector SEL rule 1 protocol tcp,udp
set interfaces ethernet eth1 traffic nat source rule 1 address masquerade
set interfaces ethernet eth1 traffic nat source rule 1 protocol tcp
set interfaces ethernet eth1 traffic nat source rule 1 port 1000-1003
set interfaces ethernet eth1 traffic nat source rule 2 address masquerade
set interfaces ethernet eth1 traffic nat source rule 2 protocol udp
set interfaces ethernet eth1 traffic nat source rule 2 port 1000-1003

Step 2: Set the following configuration in DUT1:

set interfaces ethernet eth0 address 10.0.0.22/24

Step 3: Set the following configuration in DUT2:

set interfaces ethernet eth0 address 192.168.100.2/24
set protocols static route 0.0.0.0/0 next-hop 192.168.100.1

Step 4: Ping IP address 192.168.100.2 from DUT0:

admin@DUT0$ ping 192.168.100.2 count 1 size 56 timeout 1

Show output

PING 192.168.100.2 (192.168.100.2) 56(84) bytes of data.
64 bytes from 192.168.100.2: icmp_seq=1 ttl=64 time=0.488 ms

--- 192.168.100.2 ping statistics ---
1 packets transmitted, 1 received, 0% packet loss, time 0ms
rtt min/avg/max/mdev = 0.488/0.488/0.488/0.000 ms

Step 5: Ping IP address 10.0.0.22 from DUT0:

admin@DUT0$ ping 10.0.0.22 count 1 size 56 timeout 1

Show output

PING 10.0.0.22 (10.0.0.22) 56(84) bytes of data.
64 bytes from 10.0.0.22: icmp_seq=1 ttl=64 time=0.733 ms

--- 10.0.0.22 ping statistics ---
1 packets transmitted, 1 received, 0% packet loss, time 0ms
rtt min/avg/max/mdev = 0.733/0.733/0.733/0.000 ms

Step 6: Initiate a tcp connection from DUT2 to DUT1 and try to send some messages between both endpoints

admin@DUT1$ monitor test connection server 8080 tcp
admin@DUT2$ monitor test connection client 10.0.0.22 8080 tcp

Step 7: Initiate a udp connection from DUT2 to DUT1 and try to send some messages between both endpoints

admin@DUT1$ monitor test connection server 5050 udp
admin@DUT2$ monitor test connection client 10.0.0.22 5050 udp

Step 8: Run command system conntrack show nat at DUT0 and check if output contains the following tokens:

src=192.168.100.2 dst=10.0.0.22
src=10.0.0.22 dst=10.0.0.2

Show output

icmp     1 24 src=192.168.100.1 dst=192.168.100.2 type=8 code=0 id=89 packets=1 bytes=84 src=192.168.100.2 dst=192.168.100.1 type=0 code=0 id=89 packets=1 bytes=84 mark=0 use=1
icmp     1 24 src=10.0.0.2 dst=10.0.0.22 type=8 code=0 id=90 packets=1 bytes=84 src=10.0.0.22 dst=10.0.0.2 type=0 code=0 id=90 packets=1 bytes=84 mark=0 use=1
udp      17 src=192.168.100.2 dst=10.0.0.22 sport=43319 dport=5050 packets=5 bytes=240 src=10.0.0.22 dst=10.0.0.2 sport=5050 dport=1003 packets=5 bytes=240 [OFFLOAD, packets=3 bytes=144 packets=4 bytes=192] mark=0 use=2
tcp      6 17 TIME_WAIT src=192.168.100.2 dst=10.0.0.22 sport=45628 dport=8080 packets=14 bytes=836 src=10.0.0.22 dst=10.0.0.2 sport=8080 dport=1003 packets=13 bytes=784 [ASSURED] mark=0 use=1
conntrack v1.4.5 (conntrack-tools): 4 flow entries have been shown.

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Test SNAT Network Prefix

Description

In this scenario, the translation is performed using a network prefix. The host part of the original IP address is kept, but the network part is mangled using a subnet prefix.

Scenario

Step 1: Set the following configuration in DUT0:

set interfaces ethernet eth0 address 192.168.100.1/24
set interfaces ethernet eth1 address 10.0.0.2/24
set interfaces ethernet eth1 traffic nat source rule 1 selector SEL
set traffic selector SEL rule 1 protocol tcp,udp
set interfaces ethernet eth1 traffic nat source rule 1 network 10.0.0.0/24

Step 2: Set the following configuration in DUT1:

set interfaces ethernet eth0 address 10.0.0.22/24

Step 3: Set the following configuration in DUT2:

set interfaces ethernet eth0 address 192.168.100.2/24
set protocols static route 0.0.0.0/0 next-hop 192.168.100.1

Step 4: Ping IP address 192.168.100.2 from DUT0:

admin@DUT0$ ping 192.168.100.2 count 1 size 56 timeout 1

Show output

PING 192.168.100.2 (192.168.100.2) 56(84) bytes of data.
64 bytes from 192.168.100.2: icmp_seq=1 ttl=64 time=0.414 ms

--- 192.168.100.2 ping statistics ---
1 packets transmitted, 1 received, 0% packet loss, time 0ms
rtt min/avg/max/mdev = 0.414/0.414/0.414/0.000 ms

Step 5: Ping IP address 10.0.0.22 from DUT0:

admin@DUT0$ ping 10.0.0.22 count 1 size 56 timeout 1

Show output

PING 10.0.0.22 (10.0.0.22) 56(84) bytes of data.
64 bytes from 10.0.0.22: icmp_seq=1 ttl=64 time=0.625 ms

--- 10.0.0.22 ping statistics ---
1 packets transmitted, 1 received, 0% packet loss, time 0ms
rtt min/avg/max/mdev = 0.625/0.625/0.625/0.000 ms

Step 6: Initiate a tcp connection from DUT2 to DUT1 and try to send some messages between both endpoints

admin@DUT1$ monitor test connection server 8080 tcp
admin@DUT2$ monitor test connection client 10.0.0.22 8080 tcp

Step 7: Initiate a udp connection from DUT2 to DUT1 and try to send some messages between both endpoints

admin@DUT1$ monitor test connection server 5050 udp
admin@DUT2$ monitor test connection client 10.0.0.22 5050 udp

Step 8: Run command system conntrack show nat at DUT0 and check if output contains the following tokens:

src=192.168.100.2 dst=10.0.0.22
src=10.0.0.22 dst=10.0.0.2

Show output

tcp      6 17 TIME_WAIT src=192.168.100.2 dst=10.0.0.22 sport=47834 dport=8080 packets=14 bytes=836 src=10.0.0.22 dst=10.0.0.2 sport=8080 dport=47834 packets=13 bytes=784 [ASSURED] mark=0 use=1
icmp     1 24 src=10.0.0.2 dst=10.0.0.22 type=8 code=0 id=92 packets=1 bytes=84 src=10.0.0.22 dst=10.0.0.2 type=0 code=0 id=92 packets=1 bytes=84 mark=0 use=1
udp      17 src=192.168.100.2 dst=10.0.0.22 sport=42926 dport=5050 packets=5 bytes=240 src=10.0.0.22 dst=10.0.0.2 sport=5050 dport=42926 packets=5 bytes=240 [OFFLOAD, packets=3 bytes=144 packets=4 bytes=192] mark=0 use=2
icmp     1 24 src=192.168.100.1 dst=192.168.100.2 type=8 code=0 id=91 packets=1 bytes=84 src=192.168.100.2 dst=192.168.100.1 type=0 code=0 id=91 packets=1 bytes=84 mark=0 use=1
conntrack v1.4.5 (conntrack-tools): 4 flow entries have been shown.

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