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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Is it possible to have socket TCP proxy anonymous as a system-wide implementation? [on hold]

Is it possible to have socket TCP proxy completely anonymous on a linux level implementation ?
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Tcp socket connecting on port c.adderss:443 with AF_INET , SOL_TCP and SOCK_STREAM [on hold]

How do I enable a TCP socket connecting on port c.adderss:443 with AF_INET , SOL_TCP and SOCK_STREAM in Ubuntu 14.04?
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4answers
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Is there a way to see what is actually filtering TCP port communication?

nmap -p 7000-7020 10.1.1.1 Will output all the filtered ports Starting Nmap 6.40 ( http://nmap.org ) at 2015-03-04 12:18 EET Nmap scan report for 10.1.1.1 Host is up (0.00091s latency). PORT ...
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1answer
20 views

How do I open specific ports on Linux (an AWS instance of RHEL v. 7)?

I'm using RedHat version 7. My AWS instances are in a security group with ample permissions for inbound connectivity. I can do Yum updates. The servers can ping each other. I can transfer files ...
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11 views

TCP forwarding IIS

i have a server, let's call it: GATEWAY-SERVER (GS). On GS i installed a custom build TCP proxy/forwarder. This tool accepts connection TCP level and formulates a new request towards a TARGETSERVER ...
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18 views

How to filter for the most common problems with tcpdump/tshark

I am currently using the following command in Linux to get specifics on network problems. tshark -r file.pcap -q -z io,stat,1,\ "COUNT(tcp.analysis.retransmission) tcp.analysis.retransmission",\ ...
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1answer
8 views

Windows Server 2008 sending regular TCP DNS requests to Forwarders

Our organization's primary DNS server is a Windows Server 2008 which two Forwarders set. I happened to notice on our firewall that this server is sending out regular TCP requests to the Forwarders in ...
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1answer
116 views

(Why) does FreeBSD 'net.inet.tcp.always_keepalive' violate RFC1122?

While working on a server application that runs on FreeBSD and uses TCP, I noticed that TCP keepalive probes get sent even though my application explicitly disables SO_KEEPALIVE on TCP sockets. ...
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1answer
9 views

length of Tcp segment exceed MSS

I find a weird behavior in my Linux system, when I curling a web page, the received TCP segments are significant larger THAN the MSS. here is the output of tcpdump: 00:00:00.000000 IP ...
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55 views

tcp connection reset [RST, ACK]

getting this errors looks like server is restating the connection because of some packet loss any possible suggestion's to figure out this 37713 591.925575000 ...
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31 views

Cisco ASA firewall blocking requests to internally hosted DNS server

I have a DNS server behind a Cisco ASA firewall. The Cisco firewall is performing NAT. When inside the network, I can NSLOOKUP directly to the server. When the client is external, requests time out. ...
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25 views

how to determine client side or server side retransmission from a pcap

I am trying to get some clarification on something I read here: how to calculate packet loss from a binary TCPDUMP file The first answer says that the sequence number will be the same from client to ...
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1answer
25 views

server is not responding on SYN packets

On the attached tcp dump, the first two SYN packets (#21800 and 21801) came to the server, however SYN ACK was sent for the second SYN. Is that correct behaviour? My understanding is that the client ...
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1answer
20 views

How to redirect all incoming packets to sniffer in Linux using iptables?

I need to redirect all incoming tcp packets from eth0 to current host (change ip address from 1.1.1.1 to 1.1.1.2) and outgoing tcp packets from sniffer from eth1 to another host(from 2.2.2.2 to ...
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3answers
52 views

how to use tcpdump to log only certain data in real time

I'd like to monitor network interfaces but only log things likes errors, collisions and dropped packets. The send that to stdout. – Can tcpdump be configured to do this?
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28 views

PCI says port 36141:TCP is blocked. But 36141:TCP open on iptables

PCI compliant scan fails due to port 36141:TCP is being blocked on website. I verified I cannot connection via 36141 on same server to itself: # nc -zv 127.0.0.1 36141 nc: connect to 127.0.0.1 port ...
2
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0answers
27 views

Linux - Outgoing connections from process timeout after the process restarts

banging my head against the wall with this one... I have an Ubuntu Linux server, on top of which our own process which holds 40K persistent connections to external services. When the process ...
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1answer
70 views

Concurrent TCP connections on Azure can be upto 500K. Really?

Let me be very clear at the outset that I am new to cloud technology. All I know is cloud servers are easily scalable (i.e. adding physical hardware is transparent to applications and users) and ...
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1answer
63 views

Linux clients can't connect, server and TCP Windows Size / Timestamps issue

We have a problem that a number of clients (all linux Ubuntu) are sometimes not able to connect to a remote server over SSH. If the problem occurs, Windows clients don't have that problem and can ...
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24 views

Split TCP packet - Data layer vs IPv4Layer

What is the different between split TCP packet in the Data layer compare to split the packet in IPv4Layer ?
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1answer
75 views

NetTcpPortSharing process won't start on Windows Server 2012 R2

I have a problem in Windows Server 2012 R2 : I have searched and try everything I know to fix this, but I cannot start NetTcpPortSharing service and therefore I cannot configure Windows Server ...
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0answers
79 views

HAProxy resetting backend connections

I'm in the process of setting up a series of servers as proxies to our application server, primarily to obscure the application server's IP as part of a suite of anti-DDOS measures. My goal is to ...
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1answer
55 views

TCP: out of memory - Nginx

I'm running a high traffic site on a nginx server. Last fews days I'm having problems with my VPS locking up (unable to SSH, and nginx seems to be down). When I look in the logs I can see the ...
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1answer
50 views

TCP packet loss against SQL-server

Where I work, we have had some issues with connections to the database. We get a lot of failures which appear as "recv failed" on the client side. I have used Wireshark to try to debug the problem and ...
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28 views

Reverse proxy encrypted java traffic on non-standard TCP ports on Windows Server 2012 R2

I'm trying to find a software that will run on Windows Server 2012 R2 that can reverse proxy TCP traffic without caring about the layer 5-7 details. By reverse proxy, I mean the software needs to ...
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32 views

RHEL6.4 server did not send a SYN/ACK packet in response to a SYN packet from AppDirector intermittent

In my case, client access this RHEL6.4 server thought AppDirector, so the TCP connection is from AppDirector to the server. According to wireshark, sometimes, RHEL server didn't respond for the first ...
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1answer
51 views

PHP-FPM TCP connections not terminating in time

I'm serving Wordpress pages via nginx/PHP5-FPM using APC caching (through the W3 Total Cache plugin). Nginx communicates with PHP-FPM via TCP sockets on port 9000. I've adjusted the number of max ...
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46 views

Bad ping results while testing 6000 TCP clients with 18 mbytes/s total traffic on Windows Web Server 2008

The clients are running on the machine #1. The server is installed on the machine #2. The machines have a gigabit connection through a switch on their private vlan. There are no errors in the switch ...
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1answer
7 views

SNORT only alerting on inbound traffic

I am trying to raise an alert when someone is setting up a connection to PORT 25 (tcp), whatever source or destination. For this i came up with this simple rule: alert tcp any any -> any 25 ...
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2answers
52 views

Get a website's host machine's OS/server software without access to the server

Is there a good methodology to find the operating system and server software that is being used on a served website that you don't have SSH access to? What I'm doing right now is looking at TCP/IP ...
2
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1answer
80 views

TCP Upload Speeds Slow to the Internet over LFN

I've got two Linux VMs separated by a 50 mbps WAN connection. There is about 70ms of RTT on this WAN link, so it's got some latency. I've been testing my upload throughput to the Internet from each of ...
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1answer
56 views

Hitting Ephemeral TCP Port Exhaustion

We run a high traffic website. Over the past few days, we've had several customers complain of sporadic downtime that we cannot reproduce. We have several web servers elected to receive traffic from ...
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29 views

Ghost tcp connections: ss sees them, nothing else does

We have a strange problem. Our remote server shows over 900 connections coming from our office over port 80: # ss -n | grep ESTAB | grep $OFFICEIP | grep :80 | wc -l 935 Netstat shows a similar ...
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1answer
78 views

Strange entry in open file list on Ubuntu server

On my Ubuntu server I occasionally run the following command to view any open files that are TCP connections from my server: lsof -uroot | grep 104.236.XX.XXX The last time I ran it, I saw this as ...
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1answer
52 views

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 ...
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1answer
20 views

What does the tcp_fastretrans_alert error mean?

I found this error a couple of times in /var/log/messages after experiencing some odd TCP behavior: For some reason, if I connect to for example SSH for the first time in say an hour, the connection ...
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118 views

How many concurrent TCP connections are supported in Windows Server OSs?

I am distributing software in the form of a Windows service that can be installed, and am currently trying to ascertain the specifications for supported operating systems. The service communicates ...
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49 views

Unable to connect to remote MySQL from VPS

I am trying to establish a remote MySQL connection from one VPS to another. I have tried and done everything, I have allowed the outgoing TCP port (3306) in csf.conf, I have used Iptable rules online ...
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2answers
64 views

how to force linux to accept packet with loopback ip

i have an embedded system with an Ethernet interface that needs to accept external packets with IP of 127.x.x.xx. is there a way to force Linux to accept external packets with this loop back address ...
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55 views

Always keep socat alive

I have a socat running nicely, executing my command when a connection comes in with the arguments provided. However, the issue I am having is that the socket is at EOF and the next time a connection ...
8
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4answers
257 views

Simulate slow connection between two ubuntu server machines

I want to simulate the following scenario: given that I have 4 ubuntu server machines A,B,C and D. I want to reduce the network bandwidth by 20% between machine A and machine C and 10% between A and ...
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2answers
70 views

TCP - TAP performance

Linux. Is there a performance loss from using a tap device vs a hardware one like eth0 ? The goal is to create a user space tcp/ip stack and avoid the kernel as much as possible. I would like to be ...
0
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2answers
487 views

Implementing TCP Sticky Sessions With HAProxy to Handle SSL Pass-through Traffic

How can we implement session stickiness in HAProxy when SSL must terminate on the backend servers? We need the stickiness because backends cannot share sessions. This is my original configuration: # ...
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1answer
50 views

Proxy-attack simulation

I have a WS2008 x64 server, that has NodeJS application working on its 80 port. Server constantly receives queries from different IP-addresses that are trying to use my application as a proxy. NodeJS ...
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0answers
185 views

Cannot make TCP Connection with OpenVPN Server

Client OpenVPN assigned IP: 10.8.0.2 ↓ TCP on 1194 Internet ↓ Router port-forwards 1194 to server- Public IP 104.162.67.198 ↓ Server LAN IP: 10.8.0.1 I think the above is what I am trying ...
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300 views

WSAECONNREFUSED SAP Gui unable to connect on SAP server on hp ux - inetd.conf file reference

I have a sap server installed on HP-UX vm, up and running. when I try to connect to the server from SAP client GUI installed on windows machine I get the following error --------------------------- ...
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2answers
251 views

How is a TCP request routed from a virtual machine to an outside resource and back again?

Scenario: Computer A has a local ip of 192.168.1.100, which is running a VM inside of it. The VM now makes a tcp request to an external IP address (74.125.225.98). Could someone explain how the ...
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38 views

delay in ACK packets for ldap abandon request

we have migrated from an openldap server on linux to a DirX on windows 2008. The ldap server und normal serch request behaves as expected. However with some applications (weblogic deployed webapps) ...
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1answer
83 views

Is ARP Connection oriented or connectionless?

Is ARP Connection oriented or connectionless? It uses TCP, but does that consider it connection oriented?
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2answers
70 views

Display IP & TCP statistics per interface (netstat -s with interface)

Linux has the ability to display protocol statistics with netstat -s. The output looks something like: Excerpt: 7487 times unabled to send RST due to no memory TCPDSACKIgnoredOld: 817 ...