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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Where are my TIME_WAITs on Mac OS X?

No TIME_WAITs on Mac OS X Normally, when a TCP connection is closed, the socket on the side where close() is called first is left in the TIME_WAIT state. When one of the peers is a Mac OS X (Lion) ...
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1answer
26 views

WIndows is not following TcpAckFrequency settings

This is a wierd one. I have set the tcpackfrequency to 2 and windows does not seem to honor it no matter what I do. I would need your help with this. My current template is Internet and congestion ...
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0answers
12 views

Reduce ACK frequency

Good morning, I understand the basics of the ACK response including SACK settings, receiver windows and congestion windows. I wondered is it possible for the server to tell the client the maximum ...
1
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1answer
1k views

Multiple Homed Windows 2008 Server / Windows 7 Client

I have a small Windows 2008 network, with some Windows 7 clients. The clients are both laptops with docking stations and I would like them to communicate with the Windows 2008 server (for filesharing) ...
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11answers
37k views

What is the difference between UDP and TCP?

My router has two protocols (and a "both" option) that I can select when setting up port forwarding: UDP and TCP. What is the difference between these two protocols and when would you select one over ...
0
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0answers
7 views

TCP connection between Server and client failes intermittently

There is a connection problem in on of the hospital site. The connection is between Host machine( Dell machine with windows XP ) and storage server(third party) through a Hospital LAN( a private ...
0
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1answer
47 views

Irresponsive nginx while doing “nginx reload”

While reloading nginx, I started getting errors in messages log "possible SYN flooding on port 443", and it seems like nginx becomes completely irresponsive at that time (quite for a while), cause ...
0
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1answer
52 views

SYN flooding on port 443 while nginx reload

While reloading nginx, I started getting errors in messages log "possible SYN flooding on port 443", and it seems like nginx becomes completely irresponsive at that time (quite for a while), cause ...
19
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9answers
18k views

What is the OSI model and how does it apply to todays networks?

As a system administrator what should I know about the OSI model? (Rec X.200) Briefly, what are the layers and what do they do? How much do I need to know about in my day-to-day work? How does this ...
0
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0answers
35 views

Alghough TCP SYN Backlog size is set to 128 but in practical it is limited to 16

as you know in ubuntu, tcp syn backlog size is 128 by default. i tried to syn flood my ubuntu linux by hping3. to do that, i send 100 spoofed tcp syn packets per second to the ubuntu and meanwhile i ...
0
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1answer
1k views

How to enable TCP Vegas on Centos 5.4?

I'm trying to enable TCP Vegas congestion control on Centos 5.4 box. According to Vegas home page it is as simple as echo 1 > /proc/sys/net/ipv4/tcp_vegas_cong_avoid but this file does not exist. I ...
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0answers
85 views

Windows 7 suppression of tcpip event 4199

I've noticed that Windows 7 doesn't raise event 4199 (Duplicate IP on network) consistently when assigning static IP addresses to machines. If we configure 2 machines correctly with non-conflicting ...
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1answer
87 views

TcpTimedWaitDelay is missing in Windows Server 2012

Suddenly my server log shows: An operation on a socket could not be performed because the system lacked sufficient buffer space or because a queue was full And I googled and found these links as ...
0
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0answers
38 views

No Network Traffic Between Host and VM

I have a virtual machine running that I wish to connect to a physical piece of hardware via an Ethernet connection from the host machine. This piece of hardware requires a specific IP address to be ...
1
vote
2answers
889 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 ...
0
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0answers
37 views

How to increase TCP window Size

I have a wire shark capture where SYNC happens between two nodes and when Receiver B send ACK to A with Window size =260( Actual expected 64K) after which i get a reset and again communication starts ...
0
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1answer
44 views

Windows server 2008 R2(standard) client connection is very slow after connecting above 24 client machines? Is there any client connection limit?

Windows server 2008 r2 standard is connecting 24 cilent machines after while adding extra machines to server it gets slow. In Windows server 2008 r2 maintaining the mysql database and all other client ...
1
vote
1answer
121 views

Connection SSH port 22 via domain name but not public ip address

I have a Draytek router configured to port forward SSH connections to an internal server from specific ip addresses only. Clients and myself can connect externally successfully except one who cannot ...
5
votes
5answers
9k views

How is the MTU is 65535 in UDP but ethernet does not allow frame size more than 1500 bytes

I am using a fast ethernet of 100 Mbps, whose frame size is less than 1500 bytes (1472 bytes for payload as per my textbook). In that, I was able to send and receive a UDP packet of message size 65507 ...
8
votes
2answers
1k views

How to configure iptables so an unwanted port is not reported as filtered

I'd like to stop others from seeing my ports as filtered in the nmap standard scan (unprivileged). Let's say that I have the following ports open: 22, 3306, 995 and a firewall configured like this: -...
4
votes
2answers
2k views

TIME_WAIT consumes file descriptors?

In many TCPIP and Web tunning guide, recommends increasing max number of file descriptors when getting the error "Too many open files" but, i can't see TIME_WAIT in outputs of "lsof -i" Does anyone ...
1
vote
1answer
49 views

what are the implications of running a FQDN as internal AD domain and point A-record for website to different host?

The MSP for a law firm office that has just joined our company is using a FQDN as an internal AD Domain and has been doing so for sometime apparently. They have this issue in that they have a website ...
1
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1answer
65 views

Ephemeral port reuse for TCP connections to different IP addresses

I know that a web server running a website on TCP port 80 can receive TCP connections from many different IP addresses sourced from many different ephemeral ports. Can a client initiate multiple ...
3
votes
2answers
6k views

IIS7 hundreds of connections in CLOSE_WAIT

I have a .Net application on my IIS7 server it was working fine until I had to move it to another server. I moved the exact same code to the new server and I noticed that after some hours the ...
40
votes
14answers
16k views

Why would you use IPv6 internally?

Of course, I realize the need to go to IPv6 out on the open Internet since we are running out of addresses, but I really don't understand why there is any need to use it on an internal network. I have ...
0
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1answer
97 views

Why does one of my LAN servers frequently require 21 seconds to connect?

Using a mix of Windows 7 and Windows 10 clients, one of my LAN servers tends to take 21 seconds to establish a connection. This LAN server is running Windows Server 2012-R2 and hosting TFS 2015 on ...
0
votes
1answer
25 views

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. ...
0
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1answer
5k views

Good packet generator tool for IPv6.. Does hping3 support IPv6? [closed]

Does anyone of you know any good packet generator tool for IPv6. I am very familiar with hping3, but don't know if it supports IPv6. I am looking for something which can send, tcp, udp, icmp, and ...
0
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0answers
108 views

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 ...
0
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0answers
21 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, ...
3
votes
2answers
483 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
168 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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votes
1answer
52 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 ...
3
votes
1answer
2k views

How to setup an TCP/IP proxy with traffic interception, for MS SQL traffic in this case

I would like to setup an MS SQL proxy server. It should forward all requests 1:1 and make it possible to log them, and modify some of the requests or answers according to some replacement rules I ...
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0answers
297 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 ...
0
votes
1answer
48 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 ...
0
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2answers
54 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 ...
0
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1answer
144 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 ...
0
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2answers
91 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 [...
1
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2answers
44 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 ...
0
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0answers
82 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 ...
15
votes
4answers
5k views

How are IP addresses actually assigned?

I'm having a hard time understanding how a governing body assigns IP addresses, companies use BGP to advertise those IPs, and how the internet works. Then, where the hell does DNS come in? Can ...
0
votes
0answers
26 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 ...
50
votes
6answers
297k views

In Windows, using the command line, how do you check if a remote port is open?

What is a simple way in Windows to test if traffic gets through to a specific port on a remote machine?
9
votes
4answers
6k views

Dead gateway detection on Windows 2008 Server

We have recently implemented HAProxy for stackoverflow.com. We decided on using TProxy to maintain the source address for clients connecting so our logs and other IIS modules which depend on the ...
0
votes
1answer
28 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 ...
0
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0answers
138 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). ...
5
votes
2answers
3k views

Unable to increase the dynamic port range on Windows Server 2008

I'm trying to "tune" the TCP/IP stack on some Windows Server 2008 machines by following the instructions here: http://www.outsystems.com/NetworkForums/ViewTopic.aspx?TopicId=6956&Topic=How-to-tune-...
2
votes
0answers
83 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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2answers
58 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 ...