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.
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What is a TCP Relay and when is it used? [closed]
Tcprelay is a TCP connection forwarder with load balancing capabilities. If compiled with TLS support, it may be used as SSL encryption wrapper.
What are some practical applications of TCP relay?
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What are the ports needed for L2TP VPN on Mac OS X Server 5.0.15?
I'm configuring a Mac as a server with a VPN service.
So, I opened the ports listed as used by VPN in Apple documentation:
UDP 500 -> 500 (+ESP and AH)
UDP 4500 -> 4500
Any UDP -> 1701
(I got to ...
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Millions of TCP FIN-ACK retransmissions blocking traffic on my desktop machine
In a few minutes I have received about 7 millions(!) FIN-ACK packets from IP address that belongs to Google 74.125.133.188 what totally blocked network traffic on my desktop(!) machine.
Other ...
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Tcp connection breaking, too fast for serial?
I've been having real difficulties getting a tcp connection to work with my web server. I think the issue might have something to do with the speed or ordering of the packets as the connection seems ...
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No SYN/ACK answer from server
At first I describe my LAN organization. I have 2 Networks (scheme http://take.ms/s3CSy):
192.168.0.0 / 255.255.255.0, router ASUS RT-N65U with internal IP 192.168.0.1, static external IP without NAT:...
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Can't block spammy IP
I'm being attacked by 37.59.4.76. It's sending me a great amount of data, which is destroying my dataplan.
I've added the iptables
Chain num pkts bytes target prot opt in out ...
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How to trace dropped TCP connections?
Trying to help someone with a situation where TCP connections get mysteriously dropped after a few minutes for no apparent reason (this happens even with non idle connections). Both client and server ...
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Incoming TCP SYNs possibilities
This might be a general TCP question.
Can I receive TCP SYN packet on an ESTABLISHED connection OR a connection in TIME-WAIT state?
Is this possible?
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Connect to sphinx on remote server
I recently moved sphinx onto the same server as our db so our architecture is:
File Server that hosts our web app
DB server w/ Sphinx instance (searchd)
When I try to connect to sphinx at ip.to.db....
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Network In greater than Network Out?
Stat Image: http://carzz.co/network.png
Running a small image website on EC2 without much traffic to speak of (800 user sessions per day). In looking at the EC2 Monitoring on the newly created ...
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DHCP serving has stopped working
Something happened in our server room over the weekend that had me in the office late Saturday night replacing two switches.
After powering down both racks, I have an issue where none of the computers ...
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Fixed TCP payload Size [closed]
I have an aplication that need to have a fixed (516 byes) payload size in the TCP packet. The application itself can't be modified to adjust it settings, therefore i need to tune the TCP Buffer Size ...
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trace ftp file data in wireshark
I am trying to analyze ftp traffic in Wireshark. I can see commands like Request: List, PORT.
But after FTP
Response 150: Opening data channel for directory list.
what I see immediately is
...
user107788
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Can't connect to my own machine through public IP
I couldn't figure out why I can't make a connection through my public IP. When using a local IP it works.
I have the proper firewall port exceptions, and my router NAT has the configurations for port ...
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Socket based byte counts
I see a lot of tools to get the RX and TX byte counts for transmission on interfaces, is there any tool/program that I can use to get a total transmitted byte count for a single specified socket?
I'm ...
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TCP vs UDP Error-Checking
I've bounced upon two articles that describe in-depth on how TCP and UDP connections work. However there is some kind of inconsistency. Where one article tells me that UDP does no Error-Checking at ...
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How to diagnose why a port is broadcasting a "ZeroWindow" status
I have two CentOS servers (one is an app server, the other is a DB) communicating over a port. Every once in a while, the application server starts broadcasting that the port connected to the DB has a ...
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Send TCP/IP packets down three routes and pick fastest
Does there exist a way to split TCP/IP traffic across three routes and have the first packets to reach the destination be used?
I'm imagining something like multi-homing but with the requirement that ...
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netstat shows many times deploy.akamaitechnologies.com connected to my server
Many times, after running netstat on my server, I find one of IP addresses belonging to deploy.akamaitechnologies.com connected to my server, do someone has an idea on what is happening on my server ?
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centos iptables, restrict tcp port to specific ips
I would like to modify the iptables on my CentOS 5.8 server so that only specific ips can connect to the machine on a specific port.
Currently, I have the following in my iptables file:
-A RH-...
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Redhat linux: Slow start of new socket connections
I am having problems with a Red Hat server 2.6.18.
The creation of a new TCP socket takes very long - once it is established it is fine. iptables and selinux are disabled - is there any other ...
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WSAENOBUFS errors when performing HTTP connections on Windows Server 2008 x64
We are trying to transfer large number of files from a network share into Openstack using a custom written Erlang application (using Erlang version R15B).
After about 20k files transferred the Erlang ...
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How to utilise netstat information
We have an application named "Seamer" installed on 2008R2 machine named "R2DUO" which has IP address set as 192.61.247.37 in host file and 172.26.127.40 is IP address of Ethernet card .We have two ...
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Can't mount NFS share over TCP
I'm beating my head against a wall with this one. Environment is 2 x CentOS 6 64bit installs. Both NFS client and server are fully up to date as of 1 hour ago.
I've set up an NFS export on the server:...
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telnet server not executing commands
I am connected in a telnet session in linux environment, but when I type commands and press enter, nothing happens. The TCP connection is in established state and when I checked the packets, the ...
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Setting MTU Per Destination Host
I'd like to change the MTU per host as I have a mixed infrastructure where not all devices support the same MTU. I'm on OS X 10.7 and like to set some MTU per destination host and a default one.
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Windows Server 2008 - unable to bind any TCP port
OS: Win Server 2008 RC2
Windows firewall on (no effect when off)
I have suddenly been plagued by an issue in which I cannot find any similar ones with a search.
I am running about 20 game servers ...
Kalphiter
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Is there a way to bridge two outgoing TCP connections in order to bypass firewalls and NAT?
We're all familiar with the problem of port-forwarding and NAT: if you want to expose something to accepting an incoming connection, you need to configure port-forwarding on the router or conjure up ...
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nat with iptables, re-connecting fail within about 3 minutes
i constructed a nat with iptables, as following:
echo 1 > /proc/sys/net/ipv4/ip_forward
iptables -t nat -I PREROUTING -p tcp --dport 9000 -j DNAT --to xx.xx.xx.xx
iptables -t nat -I POSTROUTING -p ...
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Nmap reporting incorrect results from an idle scan
I have a VPS that I was scanning to make sure everything is in check. A regular SYN scan reports that ports 25 and 80 are open (which they should be). When I run an idle scan however, I get back that ...
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Windows Server 2008 R2/IIS 7 refuses all outside tcp connections
I am unable to connect, for example, via http to a brand new installation of 64-bit Windows Server 2008. The server is on a domain, but is not DC (that's another problem altogether).
The IIS7 is ...
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Setting TCP_NODELAY
My application running on Solaris need send tcp packages to client in time, but sometimes the packages send delayed. I know can create socket with TCP_NODELAY to resolve the issue, but the code can ...
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TCP: Treason uncloaked! shrinks window Repaired
I have this error. The server works fine but sendmail doesn't. I can't reach it for download emails but it sends them.
I have this when I type dmesg:
TCP: Treason uncloaked! Peer 192.168.1.183:50792/...
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Monitor total bytes sent over TCP connection by ip address
Newbie sys-admin here,
On my website, users download a 50MB file. I want to be able to know whether the download has completed for them so that I can run a bash script. I'm on a LAMP stack, and the ...
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server will not reply (syn -ack)
I like to use the following commands to manage 'TIME_WAIT', in the hope to free up resources.
echo 20 > /proc/sys/net/ipv4/tcp_fin_timeout
sysctl -w net.ipv4.tcp_tw_reuse=1
sysctl -w net.ipv4....
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Why am I getting TCP retransmission errors?
I have taken some transaction captures using WireShark.
I have 3 servers, 1 web server connecting to an app server (locally) and then the same web server connecting to a remote app server... the ...
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Shrinking TCP Window Size to 0
Having an issue with any large file transfer that crosses our Cisco ASA unit come to an eventual pause.
Setup
Test1: Server A, FileZilla Client <- 1GBPS -> Cisco ASA <- 1 GBPS -> Server B, ...
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CLOSE_WAIT keeping process alive on windows
I have several java processes running on a windows server. I have noticed from time to time when I try to kill the process it remains alive. The cause seems to be sockets in CLOSE_WAIT associated with ...
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TCP Connection Establishment 3 Way Handshake Duration => Relation to Ping times?
according to: http://upload.wikimedia.org/wikipedia/commons/thumb/9/98/Tcp-handshake.svg/250px-Tcp-handshake.svg.png
1.) There is a 3 way TCP Establishment Handshake. Given I have a Ping-Time of 100 ...
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How to see actual size of tcp send and receive buffers?
we are on a debian system and are trying to tune the tcp/ip stack to our needs. We all know that you can set the maximum tcp buffer size with some kernel parameters like this:
net.ipv4.tcp_wmem = ...
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Please recommend an affordable cisco product capable of handling up to 100,000 plus simultaneous tcp connections [closed]
I am setting up my server lab, can you please recommend an affordable and very reliable router than can handle over 100,000 simultaneous open tcp connections without breaking a sweat?
Thanks!
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Windows Server 2008 constantly spamming external IP's on outbound TCP port 445
I have a Windows Server 2008 box running as a Domain Controller. I have noticed in my Cisco ASA firewall logs that this box is continuously sending out (like a thousand requests a second) requests on ...
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TCP Zero Window with no corresponding Window Update
I am trying to debug a network issue and am using Wireshark and tcpdump to grab packets from my server. I have one client application that is grabbing all my available connections and then holding ...
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Forwarding ports with ssh on Linux
I have a database server, let's call it:
dbserver
I have a web server with access to my dbserver, let's call it:
webserver
I have a development machine that I'd like to use to access a database on ...
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How to read the number of pending requests in the TCP stack backlog under linux?
I did set my kern.ipc.somaxconn kernel parameter to tweak the maximum backlog TCP size for incoming connections on my server.
I'm now looking to read the current amount of request pending in this ...
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Checkpoint FW1 logging
When I view the logs created for my checkpoint fw1, does it log connections on receiving the syn, or does it wait till the three way handshake completes? If it logs after the syn, is there anyway of ...
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Connecting to mysql over TCP hangs for 3 seconds
I have a problem with a newly installed MySQL box:
When trying to access the database with multiple clients and a lots of retries, sporadically, connecting takes longer than 3 seconds. I only get ...
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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 ...
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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 (...
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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 ...
