Recently, I conducted an experiment involving uploading a file to a server. I noticed that the acknowledgment numbers I received did not align with the sequence numbers. Please refer to the attached screenshot. Specifically, Sequence numbers I sent: 1-2897-5793 ... Acknowledgment numbers I received: 1-2897-4345-5793 ... I'm wondering why I see 4345 in the acknowledgments. I initially suspected it might be due to the Quick Acknowledgment scheme, but I remain unsure. Additionally, since the Maximum Segment Size (MSS) is 1460 Bytes, why do we observe larger segments (e.g., sequence number 2897 ..read more

If I have a scenario with two hosts. Host A and Host B. Let's say that Host A initiates a TCP connection to host B. Let's say a connection has been established after a 3-way handshake. What happens if the very first segment which Host A sends to Host B (after the handshake) is lost/dropped. We can see in the first image that the second segment is lost so duplicate acks of first segment are constantly sent to host A because acks are cumulative. I don't understand what would happen if the first data segment, sent after the handshake, is dropped. What ack # would get sent back to host A within th ..read more

I have this code down below I use to send raw socket on unix with sendto function. it works fine. If the packet is 802.11 frame, as I send the packet it gets resent by the OS with some modifications. My 802.11 Radiotap header is normally 26 bytes, and there is a 4 byte FCS (Frame Check Sequence) at the end of the packet. The resent packet's header reduces down to 13, and FCS gets deleted. so 17 bytes missing in every frame. Not just missing, but the header is completely modified. Here is an example from wireshark. I send 802.11 frames, ack packet(40 bytes) and authentication packet (60 bytes ..read more

Going crazy trying to build OpenNSL for edgecore as6700. I have Open Network Linux installed but can not do much with it. Which Nos supports powerpc CPU and has drivers for broadcom trident 2? Any guidance will be appreciated ..read more

I am hesitant to ask this because I am sure I could figure it out if not pressed for time. Furthermore, I am not familiar with how an ISP configures things post my router. In this snapshot of the traceroute to 8.8.8.8, there appears to be more than one router upstream from me since these are private IP addresses. Could this be my ISP's implementation of NAT, or is this an atypical configuration, perhaps posing a security threat? [Initially, I posted this under "Security" out of haste. Upon realizing that it was "Information Security", I quickly took it down. My apologies ..read more

After a change of ISP, I've recently gotten IPv6 access, so I thought I'd play around a little with netstat to see if it's possible to get some kind of high-level per-protocol statistics (on macOS Sonoma) to see how much of my Internet traffic is actually IPv6. My experience with the BSD-style tools is limited, and netstat is a beast of a tool. Does anyone have any tips or pointers as to whether it's possible, and if so, how to do it? My router/gateway is an EdgeRouter X, which has very limited GUI support for anything IPv6 ..read more

I have a rooted android device with a VPN app installed and I want to route all traffic from Mobile Hotspot(swlan0) through VPN(tun0). I ran this script found on github(from 5 years ago) to update iptables on the Android rooted device but my other device connected(ip 192.168.43.181/24 gateway 192.168.43.112) through swlan0 does not get the traffic routed through the VPN. Looking at the routes, I don't see any route for swlan0. Could the android script be outdated that it is missing to add routes to swlan0 device in table 61? Any hints on what could be wrong and/or how to fix it? #echo $wifiIP ..read more

I have been learning as a hobbyist about NAT Traversal using the RFC and I am confused about how relaying would work. Let's say I have a centralized server on DigitalOcean, hosted on a public address. And I have two machines I want to establish a p2p connection with. I understand that NATs would translate my private IP to a public IP and hence the central server would have my public IP via some kind of UDP state? The same connection can be done with the other NATed host I want to communicate to. So, in my understanding, the centralized server now has some kind of state about the two IPs of bot ..read more

I am reading Kurose Computer Networking book 8e, on page number 57, under 1.3.2 Circuit Switching Because it link has 4 circuits, for each link used by the end-to-end connection, the connection gets 1/4 of the link's total transmission capacity for the duration of connection. In the context of circuit switching, each link will be reserved for the network session along with transmission rate but the system allows multiple new connections to establish. For example, even a telephone call is going on, you can still call another person from different phone number  A <----> B C ..read more

I am imagining a Kubernetes IPv6 based cluster with Nodes in a private subnet and an Ingress deployed that sets up an application load balancer in a public subnet which receives a public IPv6. You can find this setup recommended for AWS EKS with IPv6 and generally also with other cloud providers. Now a IPv6 client connects to my IPv6 load balancer which then balances traffic to IPv6 Nodes. Does NAT66 happen at the load balancing step? I have tried a multitude of different search phrases. I looked at IPv6 prefixes and so forth. With IPv4 you would have NAT in use to translate from public IP to ..read more