All Questions
13
questions
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74
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Linux 6.5 netfilter NAT reuses TCP ports in TIME_WAIT status?
In my understanding, Linux (netfilter)'s NAT doesn't reuse TCP ports in TIME_WAIT status, but seemingly Linux >= 6.5 reuses TCP ports in TIME_WAIT, even if the destination is the same.
For example, ...
1
vote
1
answer
172
views
How can I get connection attempts behind a NAT router?
I've been playing with nftables recently and set up logging every incoming TCP SYN packet to my local machine. I noticed every minute I get a couple of random connection attempts on various ports (...
0
votes
1
answer
84
views
What is the correct way of shorten this nat based multiple ports?
Can these rules shorten to single line:
post-up iptables -t nat -A PREROUTING -i vmbr0 -p tcp --dport 3050 -j DNAT --to-destination 192.168.1.3:3050
post-up iptables -t nat -A PREROUTING -i vmbr0 -p ...
0
votes
1
answer
413
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Relay TCP upload traffic and make download traffic go directly to the client
This is a supplement for iptables SNAT for UDP rule is only applied to some traffic
In fact, I have three machines:
the client
the target server
the relay server
What's my motivation for doing this?
...
4
votes
1
answer
2k
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how do the world's peer to peer networks handle UDP hole punching?
With Bitcoin and Ethereum in the news so much I started to look into peer to peer networks more. My question is, do most of the people running full Bitcoin or Ether nodes have to open port 8333 to the ...
0
votes
1
answer
890
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NAT setup – unable to ping mapped host
I am setting up NAT on a Linksys WRT54GL for the first time. I'm trying to map a statically-assigned laptop address of 192.168.1.109 to port 40000, and ping it. My end goal is to enable TCP and UDP ...
0
votes
1
answer
666
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Windows TCP redirection
On my Windows PC (192.168.1.123) , I have an application that connects to 1.2.3.4 on port 3333 by default, I would like to redirect the traffic to 127.0.0.1 port 2222.
Under Linux, this can be ...
0
votes
2
answers
1k
views
Webserver behind NAT router not reachable
I have a mysterious problem with a little server that I'm running at home, behind a NAT router. I'm running several web and other services there, which I can also access from outside my LAN through ...
0
votes
0
answers
792
views
NAT doesn't allow TCP ACK for sent TCP SYN
We are using TCP Simultaneous Open for connecting TCP socket. Lets call one SideA and other SideB.
From the wireshark log I see that first two SYN sent from SideB is blocked by SideA NAT. Then SideA ...
1
vote
1
answer
593
views
Accessing two devices with the same IP?
I want to connect my laptop to two WiFi enabled digital cameras, that have the same IP hardcoded: 192.168.1.1
One solution that I've successfully tried:
Connect one device to the laptop's built in ...
3
votes
1
answer
3k
views
Router/NAT and IP/TCP header checksum
We know that IP/TCP has checksum mechanism to guarantee communication reliability.
However, when a IP/TCP packet is relayed by router or NAT, the IP header may be modified, if if the router/NAT doesn'...
0
votes
1
answer
2k
views
How do NAT or proxy react to incoming TCP SYN packet?
In some messaging systems, two messaging clients send/receive packets directly from each other in chatting or voice call. I think the basic mechanism is (TCP for example): these client programs open a ...
2
votes
2
answers
4k
views
TCP/UDP hole punching from and to the same NAT network
I was wondering if tcp/udp hole punching would still work when you are in the same network (behind a NAT), and what the packet's path would be.
What happens when using hole punching on the same ...