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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4answers
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What does a DNS request look like?

I have seen what the text representation of an HTTP request is, but what does a DNS request look like? Where in the data is the location of the URL you are trying to locate? Also, how is the ...
1
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4answers
106 views

Just one client bound to address and port: does it make a difference broadcast versus unicast in terms of overhead?

Scenario: I am implementing failed over for a network node, so my idea is to make the master node listens on a broadcast ip address and port. If the master node fails, another failover node will ...
0
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0answers
50 views

How to tell which device might be dropping packets

We are trying to diagnose a chronic disconnection issue. Overnight, nearly every night, our HTTP long poll client is disconnected from the server. The most likely proximate cause is that the longpoll ...
4
votes
7answers
5k views

Latency in TCP/IP-over-Ethernet networks

What resources (books, Web pages etc) would you recommend that: explain the causes of latency in TCP/IP-over-Ethernet networks; mention tools for looking out for things that cause latency (e.g. ...
2
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1answer
80 views

Host data transfer limit calculations and network protocol headers

OK, this might be a really stupid question, but... I'm building a web app that utilises websockets. There's fairly rapid messaging going on, so I've been taking a look at the network traffic with ...
1
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1answer
726 views

Solaris TCP/IP performance tuning

I am trying to tune a high message traffic system running on Solaris. The architecture is a large number (600) of clients which connect via TCP to a big Solaris server and then send/receive relatively ...
-1
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2answers
427 views

monitoring TCP/IP performance on Solaris

I am trying to tune a high message traffic system running on Solaris. The architecture is a large number (600) of clients which connect via TCP to a big Solaris server and then send/receive ...
0
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1answer
187 views

multicast streaming, too much network traffic?

I am thinking of switching our streaming servers to use multicasting instead of registering multiple clients and duplicating the streams manually on the server. It seems to work very well. However, I ...
1
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0answers
485 views

NIC Teaming , Multi-Homed, Active/Passive

I'm fairly new to NIC Teaming.. So I apologize if I’m not making any sense while describing this. I’ve, of course, set up plenty of simple Active/Active NIC teams for our servers without any issues ...
1
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2answers
717 views

Raw TCP/IP port forwarding software

I have server which IP address is whitelisted in some external system. And also, I have a few software developers with dynamic IPs which develop software and they need to connect to external system, ...
0
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0answers
83 views

Unable to ping one machine on the network

I have one machine on the network that can't be pinged (by name or IP) or accessed with WMI by other machines on the network. So far I have tried: Disabled firewall and AV Put onto a workgroup then ...
0
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1answer
272 views

Can ranges overlap in ReservedPorts?

The value ReservedPorts in HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\Tcpip\Parameters contains a list of port ranges to reserve so the system won't assign them to programs dynamically. ...
3
votes
2answers
1k views

IP address used by nslookup and ping is different

I have a web server hosted in the network. It has a domain name registered. However, I also host a DNS server for the LAN. So, when someone wants to access the web server, it would check the DNS ...
2
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1answer
2k views

Why ARP request is unicast?

I have a wireshark capture here that indicating a unicast ARP request from source to destination. As per my understanding ARP requests (including gratutious ARP) use broadcast. In what case the ...
1
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4answers
2k views

Error Connection to SQL Server using [HOSTNAME]\instance or [FQDN]\Instance, [IP]\instance working

This one's kind of weird, at least to me. I've got MSSQL server 2k5 (STD) installed on Server 2k3 R2 SP2 (on account of some legacy software that doesn't yet support x64 or Server 2008), using ...
5
votes
3answers
9k views

Running lsof -i shows a lot of connections in CLOSE_WAIT ? Should I worry

So I am running lsof -i | wc -l periodically and it is telling me that out of 420 lines, between 240 and 255 are in CLOSE_WAIT state. How does TCP connections enter this state ? Should I be worried ...
18
votes
9answers
9k 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 ...
2
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1answer
151 views

Disabling Operating System TCP Management

Is there a way to disable TCP state management of OS, for example on a specific port, or on another ip or if not, disabling the whole tcp management and managing it in an application with root access? ...
3
votes
2answers
2k 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 ...
3
votes
1answer
236 views

Iproute2 tools vs conntrack tools

I have a linux box which is setup as firewall/gateway for the network. Was just wondering why ss and other iproute2 tools show much less than iptables conntrack. Is it because the router function is ...
1
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2answers
358 views

Can't connect to a Hyper-V VM from anywhere but the host OS

I have an unusual situation on hand where I'm able to connect to a Hyper-V guest VM from the HOST, but not from anywhere but the host. The VM is running WIn2k8R2 and has IIS installed and Remote ...
2
votes
3answers
618 views

Can ping server but no telnet or www

I have a NAS (iomega home media 1TB) plugged in router using 1Gb ethernet cable. Occasionally I lose access to it, I can ping it by static ip, nmap to see all open ports but can't telnet to it. Also ...
0
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1answer
402 views

One Windows Domain workstation can ping gateway but gets no internet access

One of the (Windows XP SP3) workstations of our Windows Domain could not access internet anymore, this problem suddenly happened overnight. The domain controllers (there are three of them) are all ...
0
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1answer
242 views

Linux kernel 3 TCP IP tuning

I found several resources about tuning linux TCP/IP stack parameters in /etc/sysctl.conf for high bandwidth connections, but all refer to kernel 2.6. Does anyone have suggestions about how to tune ...
13
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1answer
1k views

What am I misunderstanding about calculating MTU?

Okay, I just finished resolving a jumbo frames issue between a few Xserves, a Netgear GSM7224, and a Drobo B800i. It turned out that the Xserves (Mac OS X 10.6.8 Server) and the Drobo B800i accept the ...
0
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0answers
240 views

How can I setup a Proxy I can sniff traffic from using an ESX vSwitch in promiscuous mode?

I have a pretty specific requirement, detailed below. Here's what I'm not looking for help for, to keep things tidy and on topic: How to configure a standard proxy Any ESX setup required to ...
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1answer
108 views

What would cause my SendMail server not to acknowledge receiving a TCP Sequence?

My TCP/IP Stack knowledge is a little rusty so please bear with me.... I have a CentOS 5.7 server with SendMail and am having seeing intermittent timeout issues sending email (particularly larger ...
2
votes
5answers
8k views

Windows 2008 Corrupt TCP/IP? (Ping access denied)

I'm having a weird problem on two Windows 2008 VMs (inside HyperV) running NLB. They were working at one point, but now TCP/IP appears to be corrupt. I cannot ping anything if logged in with my Domain ...
3
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1answer
260 views

Restricting ssh tunnel port access by group

My understanding is when creating an ssh tunnel to a remote machine, the ports become open on that machine for anyone to use and connect back to my local box (not just the user who opened the tunnel). ...
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6answers
415 views

What tools exist for learning and understanding TCP/IP more quickly?

I am trying to learn TCP/IP. Can anyone recommend some tools to help me better understand it?
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0answers
64 views

Best way to monitor host [closed]

I have just set up a host which receives messages from 300b to 1500b (wrapped stx etx) and replies with the same. It works fine, but sometimes it receives junk data. Is there a way to monitor this ...
2
votes
4answers
3k views

Using SAN Fiber Channel network for TCP/IP, possible?

I would like to know if it is possible to use the FC-switch (that is used for a SAN) also for TCP/IP traffic. We have servers (virtual machines) that must have a fast network for copying much data. ...
2
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2answers
165 views

Using a broadcast or network ID as src IP in PPP?

In case of PPP, are we allowed to use any IP address including broadcast & network id as the source address? For example: 192.168.1.0, 192.168.1.255? One of the customer has configured a DHCP ...
0
votes
3answers
687 views

Network device to change IP address within packets

I have an appliance with a class C IP address, for example 192.168.0.10. I can't or don't want to change this IP address. However when I connect this appliance to my network I want it to appear to ...
1
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1answer
353 views

Why won't sql server express 2008 service restart after I enable TCP/IP Protocol?

Whenever I enable TCP/IP connections on my SQL Server Express 2008 database server running on Windows XP SP3, I cannot restart the service, it simply states "The request failed or did respond in a ...
-1
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0answers
46 views

netstat showing too many connections (Established) [duplicate]

Possible Duplicate: Too Many ESTABLISHED connection from a single IP address in Apache netstat -ntp |grep 80 shows too many ESTABLISHED connection from single IP address. Around 300 of ...
4
votes
2answers
477 views

How do I fake dropped packets (or actually make them fail)?

Background One of our clients suffers from an intermittant problem with their internet where it will drop packets when a user downloads a large file (their IT is looking into the problem). I have ...
0
votes
8answers
7k views

How can I add more than 255 machines to a single Class C network? [duplicate]

Possible Duplicate: How does Subnetting Work? I'm mainly a programmer. I have no idea beyond some basic theory when it comes to Networking/Administrating. My university feels that we ...
2
votes
3answers
134 views

Odd ping result on network

Can anyone explain why when I ping 192.168.23.019 it gives me a reply from 192.168.23.17? Then If I ping .23.19 I get a request timed out reply. But I can RDP onto .23.19 These are virtual machines.. ...
2
votes
3answers
5k views

How to automate DNS server reconfiguration for TCP/IPv4 and TCP/IPv6 in Windows 7?

I need to switch Internet Protocol Version 4 (TCP/IPv4) and Internet Protocol Version 6 (TCP/IPv6) settings for DNS server configuration from "Obtain DNS server address automatically" to hard coded ...
4
votes
2answers
2k 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: ...
-3
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1answer
147 views

Can a large number of network hardware interrupts cause a machine to be underutilized?

I don't know much about networking sorry. I'm building a client / server where the server streams a lot of data to the client and I'm trying to maximise throughput (through TCP). If I run both client ...
-1
votes
1answer
45 views

Routing to an external ip

I have a bunch of equipment (RTUs) that connect to a server to download data using a fixed ip and port. Due to change of ISP provider I need to change the ip of the server that handles these RTUs to ...
0
votes
1answer
359 views

Windows XP SP3 TCP/IP No buffer space available

I have the exactly same problem as here: Windows XP TCP/IP No buffer space available On Windows XP Pro, SP3 if one does an experiment where one tries to open TCP/IP sockets in a loop (bascially, ...
3
votes
1answer
1k views

LVS Configuration issue (Using piranha Tool)

I have configured LVS on cent os using piranha tool .I am using vip of internal n/w as gateway for real server we have two NIC one having exteranl Ip and other for internal n/w which is on ...
0
votes
1answer
236 views

AFP / Apple Filling Protocol aka Netatalk access over Internet

I got a simple cloud server and thought it would be nice to have mac native afp Volumes accesss. Installed Netatalk and this seems to work pretty nice. No sensitive data or something but I don't ...
1
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1answer
1k views

Windows XP/7: custom routing for VPN connection

We are dealing with a badly configured VPN connection from a vendor, which set up the default gateway but doesn't route traffic anywhere beyond their VPN zone. I managed to do some ad-hoc routing to ...
1
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2answers
4k views

PING: timed out, host unreachable and succes all at once

Is there any logical explanation for this output? I can understand all of the three different results, but all three in one single run of PING? Could my router be defective? I have no internet ...
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2answers
456 views

TCP and Ports Connection

Can more than 1 TCP connection be active at the same time between the two ports on two different host? Please answer.
3
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4answers
508 views

Determining cause of TCP/IP connect issue without traceroute

I'm trying to connect from a company network to a host (via HTTPS), but my attempts fail with timeout. I can resolve the host. I know the host is up. I know there is a firewall filtering by incoming ...