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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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Overhead of TLS/SSL on a TCP socket connection?

Is there any bandwidth overhead on using SSL on a TCP connection? I understand, of course, the processing/memory usage overhead in encrypting and decrypting packets, but as far as bandwidth is concerned, what is the difference, if any? For example,…
Naftuli Kay
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Why are people trying to connect to my network on TCP port 445?

I was playing with my new syslog server and had my m0n0wall firewall logs forwarded as a test, I noticed a bunch of recent firewall log entries that say that it blocked other WAN IPs from my ISP (I checked) from connecting to me on TCP port 445. Why…
AtomicPorkchop
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tcpdump filter for tcp zero window messages

Is there a pcap filter for TCPDump that will allow be to filter zero window messages? I know how to filter these in a wireshark display filter (tcp.analysis.zero_window) but the amount of data I need to work with easily crashes wireshark (at least…
Kyle Brandt
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What is the best TCP congest algorithm to use for a mobile device?

Given the multitude of TCP algorithms available now and the rise of Linux based mobile devices, what are ideal algorithm(s) to consider? From reading of the various implementations, Veno and Westwood+ look interesting but I am interested in hearing…
cbc
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Karmic Koala (Ubuntu): enable remote x clients through TCP

It seems every version of Ubuntu has a different way to enable remote connections to the local X server. I'm asking this question, while I do my own research: how can I enable the X server listening to TCP port 6000 on my machine, thus allowing…
ΤΖΩΤΖΙΟΥ
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Is it possible to listen to a TCP port only with a shell, with no additional tools?

I need a very simple web server on a very small embedded system with a MISP processor. I thought that the simplest server could be a shell script listening to a TCP port. The problem is that the system doesn't have even perl. Only some basic shell…
d.k
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High percentage of lost packets - TCP, ICMP - mtr - Complain to ISP?

Problem I'm having high packet loss, according to mtr, when sending packets over the Internet. Should I complain to my ISP? Story I am reading the OReilly Linux Networking Cookbook and the chapter Using traceroute, tcptraceroute, and mtr to Pinpoint…
Kenny Meyer
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Is there a TCP Maximum Segment Size (MSS) Minimum?

I have there a OpenVPN VPN network connection, where the MSS size 60 gets send out for some reason (don't know why yet). EDIT: Reason: OpenVPN mssfix was mistakenly set to 1 36 92.064383 10.102.0.43 10.1.151.50 TCP 52 49991 → 63760 [SYN] Seq=0…
Michael Uray
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Postfix protocol error attempting email address validation with SMTP

I have some code that does an email address validation. It works by attempting a mail delivery via SMTP and then quitting without sending anything. It works most of the time, but in some fringe cases it does not. I have one of these cases and I…
mike nelson
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Why the Sequence number in an ACK packet is incremented?

I was wondering if there is any particular reason to increment the ACK sequence number instead of acknowledging the received sequence number. Why the RFC designed it this way? Actual: [SYN] SEQ=100 [SYN, ACK] Seq=300 Ack=101 [ACK] Seq=101…
L.S.
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Can excessive latency affect throughput?

I don't know if this question is on-topic here, so please redirect me if not. Trying to understand how TCP works, I had simulated a single point to point link using ns-3 simulator. On setting the bandwidth of the link to 5 Mbps, a suitable error…
pulsejet
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questions about nagle vs. delayed ack

I read online delayed ack combined with Nagle algorithm can have performance issues. But as I understand, Nagle algorithm is delayed ack. If they are not the same, what’s the difference?
del bao
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Debian 8: can't get ClamAV to listen on TCP 3310

I am trying to get Clamav-daemon running on a Debian 8 system so that it will listen on TCP port 3310. I have done the following: aptitude install clamav-daemon Then modified /etc/clamav/clamd.conf so that it now has the following at the top: #…
Doahh
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Is it normal to have HTTP 499 errors in 1 out of 4000 requests?

I made a website, behind CloudFlare, and sometimes I get an early terminated (nginx 499) request, which is really hard to work around in the codebase. This happens in about 1 out of 4000 requests. What I would like to ask is if this is normal or…
hyperknot
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ran out of tcp udp ports

How to resolve a Windows or Linux system that runs out of the tcp/udp ports on a single server? I have over around 65000 tcp/udp ports being used on a single server as a result of SQL connections, user connections for users to connect to the…
etnemo
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