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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.

TCP is just one communications protocol on the web. Others include:

  • User Datagram Protocol (UDP)
  • Internet Control Message Protocol (ICMP)
  • Hypertext Transfer Protocol (HTTP)
  • Post Office Protocol (POP3)
  • File Transfer Protocol (FTP)
  • Internet Message Access Protocol (IMAP)

TCP on Wikipedia

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Bytes-in-flight higher than receiver window in frozen client connections

I am dealing with sort of a "ghost issue". We have an endpoint URL that some people can use at all times with no issues but others have a frozen connection on the client side (checked with multiple client codes written in Java, Python C#) that never…
Ver Siw
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haproxy SSL/TLS Passthrough Proxy not working?

I want to setup haproxy as simple tcp-proxy. Below is my configuration. When I try to send e-mail via Thunderbird(pointing smtp to ip_of_my_host:8123) or simple python script I get an error about not valid certificate or certificate error. I thought…
Joshua
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No SYN-ACK Packet from server

I have two servers and I used my own embedded system with LwIP to do connection to these server. My embedded system with LwIP is the client and I have server1 and server2. I connected to server1 and end the connection before connecting to…
Sue Koh
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How to find the symmetric key algorithm being used for a TLS connection in Wireshark?

I'm doing a TLS Wireshark lab and I can't find any information in Wireshark, the lab, or online how to find this answer: What symmetric key cryptography algorithm is being used by the client and server to encrypt application data (in this case,…
cocoakrispies98
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How to get syn flags, ack flags, sequence number and acknowledgement number in tcp packets with nfqueue?

I am working on a project which can redirect the network traffic in tcp (packets sent by client to server1 will be redirected to server2) with netfilterqueue, so I need to classify the packets by their syn and ack flags, and I also needs to modify…
Alive
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Traceroute - Header Link CURL result Issue

We have systematic CURLs run every 15 mins - 2 hours from this system and logging their status. Every other CURL for the past 2 months has succeeded except this. Is there a way to identify why this one failed? This was a CURL result to my domain.…
samtech 2021
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How can I get around TCP timeouts on my international link?

I have a client/sever application that communicates using HTTP. The server is on the other side of the Earth from some of the clients. The traffic that the server and client communicate is very low bandwidth. At night the connections work…
Eyal
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High cpu usage over TCP

I'm running haproxy 2.4 and when the haproxy is configured in tcp mode i get a high cpu usage. Example: Running the stress tool to generated arround 30k connections: ./pst -c 100000 -r 100000 -u urlist.txt -p http://192.168.58.13:3128 The cpu…
André Bolinhas
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TCP DUP ACK/Out-of-Order/Previous segment not captured/Retransmission flooded on wireshark logs

Due to slow network, I installed wireshark on the device(laptop) to find this This is a log of the device using internet(Downloading a file),as you can see at the right end of the screenshot, the whole log is full of these TCP DUP…
user253776
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How to improve TCP tolerance to out-of-order delivery in Linux balance-rr bonds and/or FreeBSD roundrobin laggs?

I have 3 servers networ kwise configured as follows A is a DELL R710 is running Linux 5.13.19-1-pve Proxmox VE 7.1 and has 4 NICs teamed in a balance-rr mode bond. B is a DELL R610 is running Linux 5.13.19-1-pve Proxmox VE 7.1 and has 4 NICs teamed…
dacabdi
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AWS ALB Handshake resumption

I have a problem where the AWS ALB TCP is initiated and every request which causes unnecessary latency of 0-150ms Example from postman to show what happens at every request. DNS lookup, TCP Handshake and SSL handshake are all initiated And when I…
lat3r
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Traceroute works but nc fails - Where is my port being blocked?

I am trying to troubleshoot two Azure VNETs that have been peered together. Lets call these VNETs A and B. There are multiple services running on a VM in VNET A on different ports. I am trying to access them from a VM in VNET B. I observe the…
MojoJojo
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rsyslog - Lower throughput when using omfwd with TCP vs UDP

TLDR; I'm getting significantly lower throughput when forwarding syslog messages with rsyslog on a Redhat server with 32 cores and 128Gi RAM to a remote server using TCP instead of UDP syslog in the omfwd action. How can I use TCP for forwarding…
Wood Techie
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Clamav is very slow with tcp

I'm using clamonacc on my desktop computer and servers. I use a raspberry pi as clamd server. The clamd process only uses ~25% of all 4 cores so with htop I see it's using like ~100% and 400% is the maximum a process could use because the raspberry…
france1
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syslog-ng / telegraf : EOF occurred when idle - incompatible?

This is a follow-on question from this previous question, created because I found out more information and it's cleaner to pose this as a new question. I'm using syslog-ng OSE v3.31.2 to receive RFC3164 syslog messages over UDP port 514 from a bunch…
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