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=0.583 ms

--- 192.168.100.2 ping statistics ---
1 packets transmitted, 1 received, 0% packet loss, time 0ms
rtt min/avg/max/mdev = 0.583/0.583/0.583/0.000 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=0.521 ms

--- 10.0.0.22 ping statistics ---
1 packets transmitted, 1 received, 0% packet loss, time 0ms
rtt min/avg/max/mdev = 0.521/0.521/0.521/0.000 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

udp      17 29 src=192.168.100.2 dst=10.0.0.22 sport=33965 dport=5050 packets=1 bytes=46 src=10.0.0.22 dst=10.0.0.2 sport=5050 dport=33965 packets=1 bytes=46 mark=0 use=1
icmp     1 24 src=192.168.100.1 dst=192.168.100.2 type=8 code=0 id=101 packets=1 bytes=84 src=192.168.100.2 dst=192.168.100.1 type=0 code=0 id=101 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=102 packets=1 bytes=84 src=10.0.0.22 dst=10.0.0.2 type=0 code=0 id=102 packets=1 bytes=84 mark=0 use=1
tcp      6 17 TIME_WAIT src=192.168.100.2 dst=10.0.0.22 sport=37754 dport=8080 packets=6 bytes=338 src=10.0.0.22 dst=10.0.0.2 sport=8080 dport=37754 packets=5 bytes=286 [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=0.674 ms

--- 192.168.100.2 ping statistics ---
1 packets transmitted, 1 received, 0% packet loss, time 0ms
rtt min/avg/max/mdev = 0.674/0.674/0.674/0.000 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=0.441 ms

--- 10.0.0.22 ping statistics ---
1 packets transmitted, 1 received, 0% packet loss, time 0ms
rtt min/avg/max/mdev = 0.441/0.441/0.441/0.000 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=104 packets=1 bytes=84 src=10.0.0.22 dst=10.0.0.2 type=0 code=0 id=104 packets=1 bytes=84 mark=0 use=1
udp      17 29 src=192.168.100.2 dst=10.0.0.22 sport=41029 dport=5050 packets=1 bytes=46 src=10.0.0.22 dst=10.0.0.2 sport=5050 dport=41029 packets=1 bytes=46 mark=0 use=1
icmp     1 24 src=192.168.100.1 dst=192.168.100.2 type=8 code=0 id=103 packets=1 bytes=84 src=192.168.100.2 dst=192.168.100.1 type=0 code=0 id=103 packets=1 bytes=84 mark=0 use=1
tcp      6 17 TIME_WAIT src=192.168.100.2 dst=10.0.0.22 sport=50346 dport=8080 packets=6 bytes=338 src=10.0.0.22 dst=10.0.0.2 sport=8080 dport=50346 packets=5 bytes=286 [ASSURED] mark=0 use=1
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=0.472 ms

--- 10.0.0.22 ping statistics ---
1 packets transmitted, 1 received, 0% packet loss, time 0ms
rtt min/avg/max/mdev = 0.472/0.472/0.472/0.000 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=106 packets=1 bytes=84 src=10.0.0.22 dst=10.0.0.2 type=0 code=0 id=106 packets=1 bytes=84 mark=0 use=1
tcp      6 17 TIME_WAIT src=192.168.100.2 dst=10.0.0.22 sport=51148 dport=8080 packets=6 bytes=338 src=10.0.0.22 dst=10.0.0.2 sport=8080 dport=1000 packets=5 bytes=286 [ASSURED] mark=0 use=1
udp      17 29 src=192.168.100.2 dst=10.0.0.22 sport=41635 dport=5050 packets=1 bytes=46 src=10.0.0.22 dst=10.0.0.2 sport=5050 dport=1003 packets=1 bytes=46 mark=0 use=1
icmp     1 24 src=192.168.100.1 dst=192.168.100.2 type=8 code=0 id=105 packets=1 bytes=84 src=192.168.100.2 dst=192.168.100.1 type=0 code=0 id=105 packets=1 bytes=84 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=0.508 ms

--- 192.168.100.2 ping statistics ---
1 packets transmitted, 1 received, 0% packet loss, time 0ms
rtt min/avg/max/mdev = 0.508/0.508/0.508/0.000 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=0.607 ms

--- 10.0.0.22 ping statistics ---
1 packets transmitted, 1 received, 0% packet loss, time 0ms
rtt min/avg/max/mdev = 0.607/0.607/0.607/0.000 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=108 packets=1 bytes=84 src=10.0.0.22 dst=10.0.0.2 type=0 code=0 id=108 packets=1 bytes=84 mark=0 use=1
tcp      6 17 TIME_WAIT src=192.168.100.2 dst=10.0.0.22 sport=34682 dport=8080 packets=6 bytes=338 src=10.0.0.22 dst=10.0.0.2 sport=8080 dport=34682 packets=5 bytes=286 [ASSURED] mark=0 use=1
icmp     1 24 src=192.168.100.1 dst=192.168.100.2 type=8 code=0 id=107 packets=1 bytes=84 src=192.168.100.2 dst=192.168.100.1 type=0 code=0 id=107 packets=1 bytes=84 mark=0 use=1
udp      17 29 src=192.168.100.2 dst=10.0.0.22 sport=46642 dport=5050 packets=1 bytes=46 src=10.0.0.22 dst=10.0.0.2 sport=5050 dport=46642 packets=1 bytes=46 mark=0 use=1
conntrack v1.4.5 (conntrack-tools): 4 flow entries have been shown.

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