Questions tagged [tcp]

TCP stands for Transmission Control Protocol and is one of the core protocols of the Internet Protocol Suite. TCP complements the Internet Protocol (IP), and therefore the entire suite is commonly referred to as TCP/IP.

Filter by
Sorted by
Tagged with
1 vote
1 answer
53 views

Local WireGuard responing to a SSH TCP SYN to a wrong interface

I have a local WireGuard gateway that I am trying to manage using Ansible. I found an issue when connecting over SSH. That connection was getting timed out. After looking into the problem, I realized ...
J.Valášek's user avatar
0 votes
1 answer
133 views

Do I need to do anything to manage many outgoing connections to an outside service from a kubernetes cluster?

In my kubernetes cluster I'm running many small pods per node (about 30) and each pod creates a few TCP connections to a single service on the internet to send HTTP requests to. So each node on the ...
uylmz's user avatar
  • 101
0 votes
0 answers
18 views

How to calculate slow-start threshold

So far I observed in Ubuntu 18.04 the TCP's slow start threshold(ssthresh) shows 18, looks it seems default value. Can any one please let me know how the server calculates this value or reading it ...
Rama's user avatar
  • 87
0 votes
0 answers
47 views

TCP & Wireshark: Retransmission not working?

I traced a TCP connection in wireshark and try to understand how ACK'ing should work correctly. As you can see in the picture at some point there's a paket missing from IPx.61. Wireshark tags this ...
RaphaelBru's user avatar
1 vote
0 answers
61 views

TCP & Wireshark - Server not re-transmitting segments?

I am new to TCP-in-depth-analysis which I need for a current problem. Connections: Client = Host PC, Ubuntu 22.04.4 LTS (IP: ...60) Switch (TL-SG1016D by tp-link, Gbit) Server = Proprietary embedded ...
RaphaelBru's user avatar
0 votes
0 answers
34 views

Looking to monitor activity regarding connection attempts to closed ports on my system, what log file in should i look in? Ubuntu

I'm looking to monitor activity regarding connection attempts to closed ports on my system, as part of a server side portknocking implemetation. However, I am confused about what log file in ...
kagami's user avatar
  • 1
0 votes
1 answer
28 views

RateLimit is doing weird maths and wrong numbers on kernel

I'm trying to apply a set of rate limit within iptables, and it's doing some weird maths that i'm not able to see on the kernel why this is happen. I tried to execute same code on my local machine, ...
JustDevZero's user avatar
0 votes
0 answers
143 views

NGINX Reverse Proxy Server sending RST to upstream and FIN to downstream after 5 Minutes of inactivity

My current nginx setup always kill the TCP connection after 5 minutes of inactivity, i.e no transaction. I have this setup which requires TLS1.2 connection connecting from my internal network [client ...
user23408423's user avatar
0 votes
0 answers
71 views

AWS ALB: Are Sticky Sessions possible with TCP?

I need to load-balance my clients. Some of these clients use TCP/TLS, the rest HTTP/HTTPS. The target services of the load balancer can be in either EC2 instances or ECS containers. Also, the clients ...
Harry's user avatar
  • 463
0 votes
0 answers
116 views

TCP_NODELAY for All current sockets in linux

i want lowest latency network with tcp_nodelay., in windows OS we can easily enable TCP_NODELAY through registry of windows. i searched on the red hat website and another website but up to now, my ...
Kamala Nivas's user avatar
0 votes
1 answer
40 views

What happens if a TCP implementation retransmits different data? [closed]

No sensible TCP implementation would do this, but does anyone know what happens in practice if a TCP endpoint retransmits different data for particular sequence numbers? I couldn't find anything in ...
Adam Vartanian's user avatar
-1 votes
1 answer
64 views

How does real server, direct return server (DRS), reply to client if a load balancer (LB) uses port address translation (PAT)?

Direct Return Server overview: The DRS allows real servers to directly reply to a client without going through load balancer (LB). The LB ip (VIP) is configured as a loopback (localhost) ip for the ...
Tom's user avatar
  • 1
0 votes
1 answer
69 views

How to route TCP traffic through a fixed IP in Azure during local development?

Hello ServerFault Community, I'm working through a challenge related to accessing a third-party OPC UA server and am considering a solution using Azure's cloud infrastructure. Background Our team ...
sgabler-solytic's user avatar
0 votes
1 answer
37 views

Can iptables state miss some packets?

I tried to setup the iptable rules for MTA. As this MTA is meant only for receiving the emails I allowed INPUT packets from any to destination port 25 with state either new or established, and allowed ...
Ayush Gupta's user avatar
0 votes
0 answers
171 views

IP over LoRa: TCP timeout

I am trying to tunnel IP packets via LoRa. For this I use two devices running Meshtastic. Using ICMP I was able to determine that there is a packet loss of about 30% of the packets and a latency of ...
Marek Küthe's user avatar
0 votes
0 answers
26 views

Data from NF Tables to IP Tables

I have input data like below for NF Tables: nft add rule filter input tcp flags != syn nft add rule filter input tcp flags &syn!= syn add rule filter output tcp flags & (syn | ack) == syn | ...
Karma Yogi's user avatar
0 votes
0 answers
48 views

Parsing TCP flag Data for IP Tables

I have input file which has data like below chain:VARIABLE_IN ip_version:v4 proto:tcp sport:5401 dst_ip:18.159.158.206 dport:5432 decision:a tcpflags:&syn!=syn My code reads above data to form ...
Karma Yogi's user avatar
0 votes
0 answers
66 views

How to set TCP flags "&syn!=syn" in iptables?

I have requirement where am getting parameters to set in iptables as below: Rate Limit = 1/sec Source port = 5432 Source IP = 203.0.113.0 Protocol = tcp TCP flags = &syn!=syn iptables -A PRIO_IN -...
Karma Yogi's user avatar
0 votes
0 answers
122 views

TCP 3-Way Handshake Issue: Client not responding with ACK

I have a Java application running inside a virtual machine (VM) that uses S3-compatible storage as an object data store. Periodically, the VM is destroyed, re-deployed, and reconfigured. During the ...
sheikhisham's user avatar
0 votes
1 answer
204 views

Remote Desktop intermittent connection issues

this post is related to this:Remote desktop connection by host name vs IP address but there's more info to be presented so decided to post a new one. when connecting to remote desktop using the ...
rvh's user avatar
  • 109
0 votes
0 answers
108 views

Windows service on Windows Server 2019 stops accepting IoT device connections on public IP address and domain name

We are investigating an issue on Windows Server 2019. It runs a Windows Service that accepts TCP/IP connections (TCP/IP service bound to IP address 0.0.0.0, so listening on all network adapters). ...
J.R.'s user avatar
  • 171
1 vote
3 answers
231 views

I need a packet-level explanation of how HTTP redirects to HTTPS

I am programming an embedded web server and trying to figure out how to redirect all incoming SYN packets on port 80 to redirect to port 443. Everything I've found online is in the context of Apache, ...
StrangerDanger's user avatar
2 votes
0 answers
236 views

How to debug curl when netcat works?

The following cURL command hangs: $ curl -v http://1.1.1.1/* Trying 1.1.1.1:80... * Connected to 1.1.1.1 (1.1.1.1) port 80 > GET / HTTP/1.1 > Host: 1.1.1.1 > User-Agent: curl/8.3.0 > ...
charmoniumQ's user avatar
0 votes
1 answer
823 views

First packet isn't SYN

A Windows Server 2016 in DMZ is calling a time stamp provider service on HTTPS outside the company. The DMZ server is not a high traffic one, making around 2000 calls to the external provider per day. ...
Daniel's user avatar
  • 101
1 vote
1 answer
81 views

TCP connection not arriving at process depending on source interface

I have a strange case where a TCP connection seems to not arrive on the listening socket, depending on the source interface. The context: I'm trying to configure the Zabbix agent on a specific host (...
Daan Meijer's user avatar
0 votes
0 answers
213 views

NGINX TCP reverse proxy resolves queries differently

The Setup I currently have a server and a mongodb database running in the cloud (Oracle Cloud Infrastructure). The Problem My connection to the database is bound by a select number of static IP's. ...
Samuel Cobb's user avatar
0 votes
1 answer
216 views

Linux TCP tuning to overcome choking uplink

A linux computer is on a network link which exhibits the following behaviour: good download speeds upload/uplink starts well but after a few seconds drops to close to nothing. The Send-Q and Recv-Q ...
Konrads's user avatar
  • 880
0 votes
0 answers
27 views

Allow access to local mongodb database to a different network

Is it possible to do tcp port forwarding using windows settings without having to access router settings? I am trying to give access to my local mongodb database to someone on a different network to ...
Ahnaf Ahmed's user avatar
0 votes
1 answer
110 views

How does NGINX Plus handle server failure when doing session persistence for TCP/UDP communication?

My understanding from the NGINX Plus documentation is that their Load Balancing will route around servers that are down or swamped and that Session Persistence attempts to maintain the same server for ...
Sean Duggan's user avatar
0 votes
0 answers
93 views

Repeated TCP DUP ACK of the same initial packets

I'm using Wireshark to analyze one of the TCP conversations in my packet capture and I have this sequence where the entire conversation between these two ports is made out of TCP DUP ACK for the same ...
user199421's user avatar
0 votes
0 answers
131 views

Pgpool-II connection pooling with Load balancing disabled still make request to stand by DB node. Causing client to disconnect

I have a problem with pgpool-II load balancer. Currently I have turned off pgpool-II load balancer but somehow it still made request to my standby node. How can this happen? This make my child go ...
Hiếu Vũ's user avatar
0 votes
0 answers
44 views

TCP connection severing in Two arm load balanced environment using Kemp LoadMaster connecting to Centos servers

The configuration is one that I inherited but the connection from the LoadMaster to two appserver ends up occasionally getting severed. This will happen to each server independently, and only seems ...
Chris's user avatar
  • 1
0 votes
1 answer
361 views

Understanding TCP RST Network Capture

I only really need help understand the following image, but I will give the background for context. We have an app that is configured to use a proxy on port 8080 and requires Internet access. At ...
Mucker's user avatar
  • 367
1 vote
1 answer
37 views

Web browser fails to connect to website after 100 refreshes on client

I'm using an HTTP meta-refresh to execute a script multiple times. After 100 refreshes, the browser stalls. According to devtools, the browser doesn't even complete an initial connection to the server....
user97089's user avatar
  • 111
0 votes
0 answers
153 views

Automatic TCP SYN - cookie activation

I am simulating a SYN flood attack on a Raspberry Pi 1 with KALI Linux (ARM) installed. A similar message as mentioned in this post was printed after performing the attack: How to avoid syn cookies. ...
Gerry's user avatar
  • 1
0 votes
0 answers
22 views

TCP session refused immediately after accepting it

Host_A tries to send some data to Host_B over TCP. Host_B is listening on port 4712. Host_A is a remote PC connected on a dedicated WAN. Host_B is a local embedded device based on embOS OS, connected ...
robocat's user avatar
1 vote
1 answer
149 views

TCP Packet Loss in nftable nat chain

I am trying to connect to a Minecraft server but get a connection Timeout when tryping to connect although the Server is showing up as online Minecraft Multiplayer screen This question meight seem out ...
leonard georg's user avatar
0 votes
0 answers
716 views

Setting Up WAN + LAN Network with pfSense in VirtualBox - Troubleshooting TCP Connection Issue

Hello, I am currently in the process of configuring a WAN + LAN network within VirtualBox using pfSense (VM) as the router in my LAN. The primary objective is to establish communication between a TCP ...
lcocozza's user avatar
0 votes
1 answer
151 views

First attempt at connecting to any TCP service fails

Symptom: The first attempt at connecting to a TCP service (https, ftp, or ssh) fails. The second attempt succeeds Subsequent connections will work until there is a 15 minute period of inactivity, in ...
Randall Embry's user avatar
0 votes
0 answers
290 views

All tcp ports are not reachable on localhost (MacOS 13.4)

A friend of mine asked for help, basically any app listening on some local tcp port on localhost can't be reached. For example a node.js server running on port 8080 or 3000. Executing the command sudo ...
revy's user avatar
  • 101
0 votes
0 answers
327 views

Proxy TCP connection to different hosts depending on the origin host

I have a home server exposed with NoIP, with a wildcard domain. I have some services that run on some TCP ports (mainly game servers), and I am trying to sort of "assign" each of them a ...
Ciro García's user avatar
0 votes
0 answers
658 views

OpenVPN TCP connection to firewall failing: unknown error

I am encountering an error when attempting to connect to my office using OpenVPN. The error message: Tue Jul 18 12:34:52 2023 WARNING: Compression for receiving enabled. Compression has been used in ...
nanto's user avatar
  • 1
0 votes
1 answer
498 views

Listening on all interfaces, multiple servers

I have a server listening on all interfaces for a port (using go net.Listen("tcp", ":{port}")). I also have backup server with the same code, to start if first server fails. Both ...
Lovish Puri's user avatar
0 votes
1 answer
207 views

How to investigate not received TCP packets sent from VPN on the same LAN?

I'm setting up a VLAN on the cloud where many servers will connect to a remote host via VPN. The setup is as follows: Their Host d.d.d.72 | | ...
Younes's user avatar
  • 243
0 votes
1 answer
197 views

The TCP receiver only ack the minimum bytes of MSS one by one

The client and server nodes are CentOS7.9/X86_64. If the HTTP POST requests were sent directly to the server, there are about 0.2% of cases that may timeout. If the HTTP POST requests were sent ...
exudong's user avatar
  • 101
0 votes
0 answers
33 views

IP Based Rate Limiting for a TCP passthrough vip

Trying to set this up for one of the applications. We use Nginx under the hood. Is it possible to set up an IP-based rate limiting for a TCP passthrough VIP? I understand that it is possible to set ...
Jerrin's user avatar
  • 1
0 votes
1 answer
500 views

Proxmox host cannot reach guest: TCP client retransmitting instead of sending ACK after SYN/ACK

Setup: server (HTTP server on 80) on 192.168.1.20, clients on 192.168.1.17, 192.168.1.18 Client 192.168.1.17 can connect to the server fine (Wireshark capture on the client side attached) 1 0.000000 ...
Zixian Cai's user avatar
0 votes
0 answers
158 views

php sqlsrv error TCP Provider: Error code 0x271D

when i run php script from browser sqlsrv mssql connection working. but when i execute php script via ssh command "/opt/alt/php-fpm70/usr/bin/php path/to/script.php" sqlsrv_connect give this ...
Gökhan G.'s user avatar
0 votes
1 answer
224 views

Improve connection speed for South America users to server in Europe

I'm running an MMORPG Game with central server based in Europe-Warsaw hosted on OVH. My player base is located both in Europe (mostly Poland) and South America (mostly Brazil). Due to server ...
erexo's user avatar
  • 141
0 votes
1 answer
60 views

What is the name of the string that a service returns when you establish a tcp connection via telnet?

If you telnet to an ssh server, it will establish a connection and return a string, something like SSH-2.0-OpenSSH.... etc. Something similar happens if you connect to a mysql server. What exactly is ...
cat pants's user avatar
  • 2,293

1
2 3 4 5
34