Question

Is RUT950 supports dynamic source port allocation for Source NAT on WAN interface ?

I have a server connected behind Router 4G Teltonika RUT950 and I see  that Teltonika modify the source port  and not in a random dynamic allocation way. I can see that the This Router reused same sequence of source port seen in previous connections so fast "less than 2 minutes" as it causes instability on my application.

It is possible to configure the router Teltonika RUT950 to perfrom random dynamic source port allocation or configure it to not modify the source port of the original connection ?

Regards, Vincent

Answer 1

Hi,

Could you draw a simple network topology with relevant devices, IPs and port numbers (can be dummy IPs and ports)?

Comments

1) Original Connection : Traffic sent by my probe

Source IP: 192.168.5.10 , Destination IP : C&C 88.88.88.88 Source Port : 45021 Destination Port : 666

2) Connection translated by Router Teltonika RUT950  

Source IP : 4G IP, Destination IP : C&C 88.88.88.88 Source Port : 44444 Destination Port : 666

My probe establish TCP sessions every 15s to his C&C server. The Router Teltonika RUT950 doesn't perform the Source NAT by allocating dynamic source port. From Logs of my C&C server, I can see that the router reused the same sequency of source port for all my connections.

That's NAT behavior causes instability of my application.

With Router Teltonika RUT950, is it possible to configure the Source NAT to either not change the source port of original connection or by allocating random source port ?

Answer 2

1) Original Connection : Traffic sent by my probe

Source IP: 192.168.5.10 , Destination IP : C&C 88.88.88.88 Source Port : 45021 Destination Port : 666

2) Connection translated by Router Teltonika RUT950  

Source IP : 4G IP, Destination IP : C&C 88.88.88.88 Source Port : 44444 Destination Port : 666

My probe establish TCP sessions every 15s to his C&C server. The Router Teltonika RUT950 doesn't perform the Source NAT by allocating dynamic source port. From Logs of my C&C server, I can see that the router reused the same sequency of source port for all my connections.

That's NAT behavior causes instability of my application.

With Router Teltonika RUT950, is it possible to configure the Source NAT to either not change the source port of original connection or by allocating random source port ?