All Questions
20
questions
0
votes
0
answers
73
views
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, ...
- 41
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
82
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 ...
- 103
0
votes
1
answer
409
views
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?
...
- 13
0
votes
0
answers
129
views
Returning tcp/udp packets to sender
I'm using a Linux machine with WiFi hotspot to test the WiFi stack of an embedded device. For context, the embedded device is designed to send and receive encrypted packets to/from a remote server.
To ...
- 1
0
votes
3
answers
583
views
Connect a socket to another PC in same NAT
Hey I've got two machines on the same network. They get their IP info back from an external webserver. Same IP due to NAT but different ports locally. Hmm that's weird.. they can't socket up or even ...
- 11
0
votes
1
answer
2k
views
SSH file transfers slow with lots of TCP retransmissions
Good evening,
I use SFTP (File Transfer over SSH) from a computer (Windows 10) to a Synology NAS. Both devices are behind NAT on different locations. Around 3 weeks ago, whenever I initiated a ...
- 31
4
votes
1
answer
2k
views
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 ...
- 651
0
votes
1
answer
890
views
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 ...
- 229
2
votes
0
answers
1k
views
netflix stall via linux iptables nat, tcp checksum errors (with workaround)
I've been trying to track down this problem for several days. I still haven't worked out what is going on, or how to fix it properly, but I do have a workaround.
Problem summary
Netflix stalls when ...
- 21
0
votes
1
answer
662
views
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 ...
- 1
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 ...
- 161
0
votes
0
answers
787
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 ...
- 101
1
vote
1
answer
591
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 ...
- 1,664
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'...
- 3,035