I have an AWS ubuntu instance with the following network interfaces:
ens5, ip: 172.XX.XX.XX
A5TAP, ip:192.168.233.1 (VPN)
How do I udp port forward port 10000-10200 to 192.168.233.52:10000-10200?
I tried a the obvious commands below for a single port 10009, but it is not working:
sudo iptables -t nat -A PREROUTING -p udp --dport 10009 -j DNAT --to-destination 192.168.233.52:10009
sudo iptables -t nat -A POSTROUTING -p udp -d 192.168.233.52 --dport 10009 -j SNAT --to-source 172.XX.XX.XX
sudo iptables -t nat -L -n
=======What I tried so far:
I am trying to port forward port 10009 all udp traffic to ens5, to 192.168.233.52 in A5TAP:
172.XX.XX.XX:10009 -> 192.168.233.52:10009
The udp stream is a video stream.
I followed this tutorial, but it is not working. As when I shoot the udp stream to 172.XX.XX.XX:10009, no video is showing.
If I do sudo tcpdump -i ens5 -n udp port 10009:
tcpdump: verbose output suppressed, use -v or -vv for full protocol decode
listening on ens5, link-type EN10MB (Ethernet), capture size 262144 bytes
14:08:51.035226 IP 59.XXX.XXX.XXX.46696 > 172.XX.XX.XX.10009: UDP, length 1400
14:08:51.035703 IP 59.XXX.XXX.XXX.46696 > 172.XX.XX.XX.10009: UDP, length 510
(and so on....)
That means my AWS instance is receiving the video stream from my machine.
But when I do sudo tcpdump -i A5TAP -n udp port 10009, there are no traffics.
If I joined the machine with video stream to A5TAP VPN, and send udp stream to 192.168.233.52:10009, I can see the stream.
Thanks to maxstr's answer, the port forwarding between interfaces in the same machine worked:
sudo tcpdump -i A5TAP -n udp port 10009:
07:45:53.701800 IP 192.168.233.1.49538 > 192.168.233.52.10009: UDP, length 700
I believe what you want is the following:
sudo iptables -t nat -A OUTPUT -p udp --dport 10009 -j DNAT --to-destination 192.168.233.52:10009
because the PREROUTING chain will not be in the path of local outbound traffic. OUTPUT will.
Related
I need to set up access to the HTTP(S) servers on devices like KVMs and PDUs on a private network (192.168.0.0/24). I must get through an isolated network (10.0.0.0/8) limited to ports 22 and 443. I have a dual-NIC Linux server inside the network that serves as a gateway to the private network. See diagram Here:
Network Diagram
I need to use a forward SSH tunnel to get to the Linux gateway, then use iptables NAT to route HTTP(s) traffic to the web frontends on the devices.
I've observed with both tcpdump and iptables trace that the inbound HTTP(s) request through the SSH tunnel shows up on interface lo , not eth1 as one might expect.
This has led me to come up with the following nat and filter rules:
*nat
-A PREROUTING -i lo -p tcp -m tcp --dport 8080 -j DNAT --to-destination 192.168.0.100:80
-A PREROUTING -i lo -p tcp -m tcp --dport 8081 -j DNAT --to-destination 192.168.0.101:443
-A POSTROUTING -d 10.0.0.0/8 -o lo -j SNAT --to-source <10.gateway_IP>
COMMIT
*filter
:INPUT ACCEPT [37234:5557621]
:FORWARD ACCEPT [0:0]
:OUTPUT ACCEPT [26648:27864039]
-A FORWARD -d 192.168.0.0/24 -p tcp -m tcp --dport 80 -j ACCEPT
-A FORWARD -d 192.168.0.0/24 -p tcp -m tcp --dport 443 -j ACCEPT
COMMIT
So, when I set up the tunnel with:
ssh -L 8080:<gateway>:8080 <user>:#<gateway>
Then making sure on the gateway:
$ sysctl net.ipv4.ip_forward
net.ipv4.ip_forward = 1
and then execute http://localhost:8080,
The packets make it out of the tunnel onto the gateway, out of interface lo, but iptables doesn't seem to forward it to the destination in the PREROUTING rule. stderr from the tunnel returns "Connection refused."
What am I missing?
I want to record the packets (using tcpdump) after iptables, but it seems that tcpdump will record all the packets. I don't want the packet dropped by iptables.
Is there any way to
record the packets after iptables? or
output the packets (processing by iptables) into pcap/log file?
Thanks.
Tcpdump acts before iptables for inbound traffic, but you can use iptables "NFLOG" extension to reach your goal: http://ipset.netfilter.org/iptables-extensions.man.html#lbDI
Using "NFLOG" destination you can log desired packets to userspace application, and that's where tcpdump belongs (you can also assign traffic to a specific group and then tell tcpdump to listen from it).
Webserver (very basic) example, let's pretend you are accepting http/https traffic and dropping ssh:
#BASIC RULES
iptables -A INPUT -p tcp --dport 80 -j ACCEPT
iptables -A INPUT -p tcp --dport 443 -j ACCEPT
iptables -A INPUT -p tcp --dport 22 -j DROP
#NFLOG REDIRECT ONLY HTTP TRAFFIC
iptables -A INPUT -p tcp --dport 80 -j NFLOG
#TCPDUMP ONLY ON MATCHED TRAFFIC (=HTTP)
tcpdump -i nflog
I am using WireGuard (WG) as a VPN and only routing certain port based traffic over it. On the ingress side of the tunnel the traffic first hits eth0 then goes on to the WG TUN interface, wg0, so the following rule works for forwarding on ingress:
-A PREROUTING -d 192.#.#.# -i eth0 -p tcp -m tcp --dport 7054 -j DNAT --to-destination 10.#.#.#:7054
However I can not get traffic routed from TUN interface to eth0 on the egress side of the tunnel with the following rule, I think due to the "tunnel" being virtual and the traffic first must cross eth0 so PREROUTING is not valid??? I am not sure how to think about the TUN interface with regards to the routing sequence, i.e. is this still PREROUTEING or POSTROUTING or somewhere in the middle?
-A PREROUTING -d 10.#.#.# -i wg0 -p tcp -m tcp --dport 7054 -j DNAT --to-destination 192.#.#.#:7054
I tried the following to see if PREROUTING would then work for the wg0 interface but it did not. I also tried this with POSTROUTING, but not the solution.
iptables -t raw -A PREROUTING -i eth0 -j NOTRACK
I have a machine with 2 interfaces:
eth0 inet addr:1.1.1.1
eth1 inet addr:2.2.2.2
eth0 is a server, eth1 is the network on virtual machine.
I have ssh on server, so 1.1.1.1:22 is busy.
I need a rule for redirecting incoming connections on eth0 port 6000 to eth1, ip 2.2.2.100 on port 22 (virtual machine ip).
In this mode if I did, on an external machine,
ssh -p 6000 root#1.1.1.1
I would login on the virtual machine.
I tried this rule but it didn't work:
sudo iptables -P FORWARD ACCEPT
sudo iptables -t nat -A PREROUTING -p tcp -i eth0 --dport 6000 -j DNAT --to 2.2.2.100:22
Well there are like 1 million scripts/tutorials/things for this case, but if someone lands from google to here is something like this:
iptables -I FORWARD -d 2.2.2.2 -m comment --comment "Accept to forward ssh traffic" -m tcp -p tcp --dport 22 -j ACCEPT
iptables -I FORWARD -m comment --comment "Accept to forward ssh return traffic" -s 2.2.2.2 -m tcp -p tcp --sport 22 -j ACCEPT
iptables -t nat -I PREROUTING -m tcp -p tcp --dport 60000 -m comment --comment "redirect pkts to virtual machine" -j DNAT --to-destination 2.2.2.2:22
iptables -t nat -I POSTROUTING -m comment --comment "NAT the src ip" -d 2.2.2.2 -o eth1 -j MASQUERADE
What I am trying to Achieve:
Test/Configure All NAT Scenarios(Full Cone,Port Restricted etc) by (1) .using iptables (2) ethernet interface (3) loopback interface (Using only one machine)
Set Up following configuration :
I am running one VM in a Linux BOX, and performed following configuration :
Linux BOX IP is : 192.168.0.4
Linux Box Virtual Box Gateway IP is : 192.168.56.1
Running Stun Server Binded on : 192.168.56.1 (Primary) and 192.168.0.4 (Secondary) on Linux Box
Running Stun Client on VM(Running on above Linux Server) at 127.0.0.1:2000 , and configured iptables rules to forward loopback interface traffic to ethernet interface (192.168.56.102) and vice versa.
Expected Result
I should be able to configure each NAT Simulation via iptables/ethernet/loopback interface on which STUN Server running on Host and Stun Client running on VM, and it should tell the type of NAT
Actual Result
iptables doing nothing with the packets in/out to loopback interface
socket sendto call fails with error : "error 22 invalid arguement" because socket has bind with 127.0.0.1:2000 and destination address is : 192.168.56.1
See below in short
[Loopback-Interface(127.0.0.1 :2000 / *Running STUN Client*/ VM) -->[*IPTABLES RULES TO/FROM*] <-- Ethernet-Interface(VM -- 192.168.56.102:2000) ==>|| ==> HOST(Gateway - 192.168.56.1:3478 - *Running STUN Server*)] ::
Examples Rules ::
sudo iptables -t nat -A POSTROUTING -o eth0 -p udp --source 127.0.0.1 --sport 2000 -j SNAT --to-source 192.168.56.102
sudo iptables -t nat -A POSTROUTING -o eth0 -p tcp --source 127.0.0.1 --sport 2001 -j SNAT --to-source 192.168.56.102
sudo iptables -t nat -A PREROUTING -i eth0 -p udp --destination 192.168.56.102 --dport 2000 -j DNAT --to-destination 127.0.0.1
sudo iptables -t nat -A PREROUTING -i eth0 -p tcp --destination 192.168.56.102 --dport 2000 -j DNAT --to-destination 127.0.0.1
It Seems iptables doesn't pick packets from loopback interface
References : http://www.linuxquestions.org/questions/linux-networking-3/iptables-redirect-127-0-0-1-to-192-168-1-113-a-818817/
Please let me know if any body can help on this.