TCP and IP are two important protocols used in networking today. Due to their importance, the Internet Protocol Suite is also commonly known as "TCP/IP"

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Two subnets on one LAN

I have a simple 192.168.1.x/24 LAN GW & DNS = 192.168.1.254 My workstation is 192.168.1.101 I wish to setup a parallel mirror LAN for testing using a 192.168.10.x/24 subnet on the same switch. ...
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NLB cluster []: Timer starvation has been detected. This

we have two node NLB cluster basicly for http reguests. Server system logs have theese warnings: NLB cluster []: Timer starvation has been detected. This might be due to a denial of service attack or ...
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18 views

How to I diagnose downloads slowing over time?

I am trying to track down a strange networking problem. Basically, a http download from a tomcat server is slowing down over time. For example, the download speed starts at 700kb, then slows to 650, ...
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2answers
72 views

Not all printers are deployed on the client using Group Policy

Situation in our environment we are using the following servers to deploy printers in our domain forest: Windows Small Business Server 2008: contains the group policy to deploy the printers Windows ...
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2answers
142 views

What is the best IP subnet to avoid subnet collisions?

My company installs specialized webservers for tracking commercial building HVAC performance. These machines each have two LAN adapters--a primary and a secondary. The way the system is intended to ...
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1answer
49 views

How does a DNS forwarder build its cache?

I know that DNS forwarder cache is build up from responses by the authoritative name servers. But does it build its cache from the requests process by it? Let me explain what I mean. Lets say I have ...
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76 views

uWSGI TCP/IP host:port vs Unix socket

We are running a Python WSGI server (uWSGI) and changed to socket file instead of a tcp/ip localhost:port connection. Now our uwsgi logs are full of errors like IOError: write error SIGPIPE: writing ...
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38 views

Static IPs and New Domain Controller and Domain within existing Forest

I have a forest domain chicago.example.com that contains 2 domain controllers in it, in which I had joined a 2012 Server to the forest domain called DOMAINCONTROLLER3. I plan to promote this server to ...
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2answers
49 views

TCP/IP - why does routing without masquerading work?

I thought a data packet from another subnet is always rejected. But when I have two hosts (h1 and h2) in two different subnets (s1 and s2) and one router (r) with activated ip_forward and access to ...
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1answer
59 views

TCP connection not established: Can't Connect to MySQL Server on Remote Connection (10060)

I'm running MySQL 5.6 on a WinServer 2012 system. It works great. The server is on our office intranet, not accessible to the outside world. I normally administer MySQL remotely from my office on my ...
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2answers
42 views

A small puzzle about routing

This is a followup to this question I saw on SuperUser, to which no answer has been provided. A user deleted the second route in his routing table, # ip route show default via 192.168.73.1 dev ...
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40 views

Configure a websocket server in front of HAProxy

I have a small python server script which creates a websocket connection and accepts base64 encoded IP packets (very similar to this). As of now my script decodes the IP packet and sends it out into ...
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57 views

Tracert not resolving IP

I know this is propably a basic question, i did some research on the net as to the whys and hows and got only more confused. I wanted to ask why tracert returns this : Tracing route to youtube.com ...
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22 views

Not getting TCP Update Window packet after TCP Zero Window begins

Once I get TCP Zero Window during data transmission, I can't send data anymore in that desktop sharing session. Even I stopped the data sending to check if it can resume but no benefit! In my test ...
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2answers
125 views

TCP timeout for established connections in Windows

I have the following situation: Application (Firebird DB client) on a client computer opens a TCP connection to server on port 3050 Application crash on client, application terminated netstat on the ...
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26 views

Web application access permission

I have a web application that uses SQL server . SQL server is hosted on a server and accessed using port 1433 . My question is will the user who is accessing my application required to be able to ...
2
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0answers
51 views

So many retransmission over NSX enabled vDS of vSphere

I'm currently on test of VMware NSX network environment and met some trouble. My Environment is: Management Cluster with 3 Hosts and NSX components on 2 dedicated Hosts Compute Cluster with ...
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92 views

Apache2 send [FIN, ACK] immediately

Currently we have an apache2 with mod_proxy in front of a tomcat7. What we have experienced is that some requests have been dropped by apache2 from time to time (i.e never been forwarded to tomcat7). ...
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2answers
50 views

Do Browsers implement the HTTP protocol?

My understanding of the TCP/IP stack is that the Application layer (layer 4) consists of protocol implementations such as HTTP. Do user-agents like web browsers implement this HTTP protocol ...
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94 views

Multiple IP Addresses from DHCP

I have a problem with multiple processes needing to bind a TCP socket to the same port in Windows Server 2008. At the moment I believe this is causing some unexpected erratic behavior as a race ...
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2k views

When to use routable vs non-routable IP addresses [closed]

As I understand it, there are several "non-routable" IP ranges: class A reserved space 10.0.0.0/8 class B reserved space 172.16.0.0/12 class C reserved space 192.168.0.0/16 class E reserved for ...
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1answer
285 views

How does stunnel redirect traffic?

I am familiar with the stunnel.conf and I know how to specify which unencrypted ports it listens to and to which encrypted ports it redirects, but I would like to understand how it gets the power to ...
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1answer
30 views

TCP/IP ack loss between firewall and server

Scenario: Client connects to Server using TCP/IP. Issue: During initial TCP/IP connection setup, the ACK packet [3rd step in TCP] sent from Client to Server has crossed the firewall [evidence from ...
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79 views

Network speed between Windows 7 machines sharing over samba/SMB not reaching 10Gb/s

I have two Windows 7 Machines that are connected via 10Gb/s Intel Server Cards on a 10Gb/s Switch an a subnetwork(Physically separate from the larger main domain network). I'm trying to copy files ...
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41 views

Many TCP retransmissions with NAT interface in VMware Workstation

I have a problem with TCP retransmissions between outside servers and a virtual machine in VMware Workstation 12 that is configured with a NAT interface (vmnet8). To simulate a slow link, I have set ...
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1answer
64 views

Can't communicate out of VM instance for Modbus TCP/IP over port 8080 - routes poosibly required

I have used Google Cloud Developers Console to set up a Windows 2012 Server. I am trying to use this a web server for monitoring hardware utilising Modbus TCP/IP. I have installed a SCADA software ...
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1answer
151 views

How many data channel ports do I need for an FTPS server running behind NAT?

As the title states, I currently have an FTP server accessible via FTP or FTPS (explicit) running NATed behind a router. The server is running Windows Server 2012 R2 with IIS 8.0 (I believe that is ...
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2answers
438 views

IP on different subnet mask [closed]

I'm still learning the ropes of Windows Server (specifically 2012R2). My assigned task is to setup a static local IP address, I managed to get it set to 192.168.1.96 (with subnet mask 255.255.255.0) ...
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1answer
161 views

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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124 views

Static ip addressed hardware unreachable

I need help, I have multiple things (NAS box's and the like) on a static 10.10.10.x network. My new situation forced me to use an Air Card on one laptop and using Internet connection sharing to allow ...
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33 views

Corrupted files when downloading with HTTP

With my UMTS connection most archives > 50 MB are corrupted when downloading them via HTTP. If I switch to HTTPS the problem is gone. The problem should not reside in my network, because I have an ...
2
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2answers
439 views

TCP sequence number randomization

In a recent interview, my friend was asked about firewalls’ TCP sequence number randomization feature. The interviewer mentioned that we know that a firewall randomizes the TCP sequence number, but an ...
1
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1answer
74 views

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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1answer
59 views

When connecting to localhost, does a full SYN, SYN-ACK, ACK handshake still occur?

This question is addressed, primarily for Linux. While I could find the answer myself, I'm hoping someone out there just knows the answer implicitly and can save me some time. If I'm connecting to a ...
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64 views

What should happen when receiving an ICMP Fragmentation Needed message?

In general, and in particular on a Solaris 10 machine ... See, we are having an issue in our network. I handle some reverse proxy instances on a Solaris 10 server that is behind a load balancer, and ...
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2answers
668 views

Can I add a static route to a VPN network if the default gateway IP is dynamic? (Windows 7)

Can I add a static route to a VPN network if the default gateway IP is dynamic? (Windows 7) This is easy to solve with a permanent route if the default gateway does not change as you can do this: ...
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1answer
99 views

Why is wireshark capturing packets not destined to my host? [closed]

My IP was configured as 192.168.101.91, I don't understand why my host is receiving packets which have a destination address of 192.168.87.203(and many other IPs which I didn't capture) given that I ...
2
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0answers
423 views

Does a ping to 127.0.0.1 hit the network card? Which RFC / standard states that? [closed]

I recently did an exam where one of the questions stated that you can run ping 127.0.0.1 on a computer to verify if its network card is working. I have already read on multiple sources that this ...
2
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1answer
111 views

A local IP address (RFC 1918) on my network that is not … local

I've noticed an IP address today on my network (192.168.15.1) which when visited actually goes to a page that has a router webconfig page (Not my router) The puzzling thing is that i tried traceroute ...
2
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0answers
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Event id 4227 tcp/ip warnings on Windows 7

We're deploying a new image out to the field, and we're seeing tcp/ip event id 4227 warnings periodically throughout the day (1-3 a day). The event message reads as follows: TCP/IP failed to ...
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2answers
73 views

ASN number basics [closed]

I have the basic idea of ASN numbers. My question is how do routers know about them? It doesn't seem like it is signified by any bits in the datagram, so I assume it's done in the protocol. Once you ...
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1answer
45 views

high availabilty port forwarding in mswindows

I need port forwarding for a mswindows host, but I need something which can handle more than one target with fail over. There are no end of tools to do this on Linux/Unix (haproxy, balance, ...
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1answer
243 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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2answers
528 views

Why I cannot access EC2 instance public IP from inside of instance itself?

Here is an example, I have an Linux instance , say, private IP is 10.10.10.10, public IP is 54.54.54.54. Inside the instance, I could successfully ping it's private IP(10.10.10.10) and localhost. ...
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17 views

Can a firewall handle packets being sent to it by a network TAP?

We have the intention of examining incoming mails for security purposes. In order to do so we figured out the solution will include: Network TAP - To copy all SMTP traffic to the firewall Firewall - ...
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1answer
716 views

Can a port be in the listen state and be closed?

Servers running Debian7.7, Mongodb 1.2.0.6-1.1, Nmap6.0 - Thanks for your time. I've user who can't connect to mongodb from his Win7 desktop. He has mongodb installed on it and he's trying to connect ...
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225 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 ...
4
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1answer
238 views

How does Windows 2008 specifically select ephemeral ports (does it test to avoid conflicts)?

I have a server application which uses permanently connected incoming ports within the range that W2k8 now uses in the IANA recommended range of ~49000-65000. (For legacy reasons it's extremely ...
7
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2answers
4k views

TCP Dump, cannot understand these 4 lines?

I need support understanding these 4 lines. looks like tcp dump but im actully not understanding what exactly is happening here. 13:13:22.407445 IP 192.168.246.128.54955 > 192.168.246.13.80: S ...
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An already acknowledged data sequence number is coming back as null byte repeatedly

There is a transaction processing server (TP-Server) to which my application (Client) connects to. We are seeing a strange packet sequence where in the TP-Server is sending a PUSH packet with a null ...