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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Sonicwall VPN site unable to communicate with Windows PDC

(First question, please be patient) We have a SonicWall NSA-2400 appliance as our firewall within our primary location. (SonicOS Enhanced 5.1.0.8-17o) Remotely we have 2 sites with Cisco 2800 ...
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316 views

Wrong DNS for just one site on development machine

www.superyoink.de is my clients' website. I can access it from any machine except my development one. If I ping it on my development machine, I get 80.67.28.107 - this is wrong. My laptop, next to ...
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20 views

Printer lpd daemon refuses print job if a command's new-line sent separately — bug?

I'm encountering some printer LPD daemons which work fine if the new-line is sent in the same packet as the command, but break if the new-line is sent in a separate packet. Is that a bug in these ...
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2answers
152 views

How to implement firewall in LAN(out of users' os) like EC2 have done?

In aws ec2, users can set up security groups which works like a firewall, usually, firewall work behind a gateway/nat server, however, I found that firewall in EC2 works in the LAN, too. For example, ...
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279 views

switch OFF syn cookies

We have several servers they have public IP's, but work together (one is with Load Balancer, orther with Apache Web server, other with MySQL and so on. Most of the ports are fire-walled, so only ...
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484 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 ...
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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 ...
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1answer
725 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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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 ...
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1answer
540 views

Changing TCP/IP IPID sequence generation algorithm on Windows Server

a recent security review on a customers webserver yielded the following results: "[...] The system under test is using incremental ip ids. This means that every outgoing ip packet has an ...
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1answer
370 views

Can't connect using TCP though UDP/ICMP works

My office changed IP addresses yesterday and since then we can't access any site hosted by mediatemple.net plus a couple of other sites. The office connection is ADSL (PPPoA). Both MT and my ISP ...
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1answer
412 views

Moxa serial-to-ethernet connection problem

We have a Windows 2003 Server (32-bit) running in VMWare and connecting to 2 Moxa NPort 5450 serial-to-ethernet devices. We are experiencing a sporadic "disconnect" with the serial devices attached ...
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747 views

Network Transfer Rate on SMB/FTP

We're trying to optimise our network transfer rate from the client PCs to the file server, but having no luck. If I run an iperf test between a client PC (Windows XP) and our server (Linux) with a ...
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2answers
267 views

Validity of my basic Performance Testing Results on a LAN

Networking is not my main job and i am hoping you guys can comment on my test procedure so far to identify PCs best to host a few voip softphones. Our 100Mb LAN comprises of 40 Win XP/2000 PCs and a ...
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4answers
2k views

how to make standard ssh port a stealth port?

I'm running a personal ssh server on a nonstandard port. If someone tries to log into my ssh server thru the standard port 22, it seems that the server sends "Connection refused" message. $ ssh ...
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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 ...
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5answers
1k views

What ports are least likely to be probed on the internet?

Suppose you've got a server that runs insecure software and you have to make it publicly accessible, what ports are "safest" for providing that service on the internet. By "safest" I mean least likely ...
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1answer
103 views

TCP/UDP Connection States documentation

Does anyone know where to find documentation for TCP/UDP connection states? Preferably non-Microsoft with unix backing. Basically, I'm looking for more information about TCP established, TCP ...
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5answers
341 views

Help me understand Public/Private IP space and NAT

I just started working at a small-medium sized business after graduating school. So much of my knowledge is high level concepts without a lot of hands on. My understanding that according to rfc1918 ...
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3answers
153 views

What is TCPIPv3

I have been reading at quite a few places about TCPIP v3 being out ... I wanted to know what is this TCPIPv3 and what are differences between 2 and 3. I tried to google out the answer but could not ...
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6answers
2k views

How to capture postscript output via TCP/IP? (for testing purposes)

We have a propriety system that talks to various printers across multiple sites via TCP/IP. The system only outputs Postscript, which obviously sends via TCP/IP. I'm really wondering is there any kind ...
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2answers
207 views

How to globally limit total number of TCP connections with iptables?

I'm having quite a difficult time figuring out how to REJECT both inbound and outbound connections from a machine with iptables once the total number of TCP connections hits a global maximum without ...
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3answers
1k views

Is there any difference between prisoner.iana.org, blackhole-1.iana.org, and blackhole-2.iana.org?

Probably not the most useful question, but I'm curious: I understand (in theory) that if a reverse lookup for a private IP makes it makes it past your own DNS servers you should get back ...
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392 views

DHCP IP address with a client specified DNS server? Is this against spec?

I have some embedded network devices that allow me to specify whether or not they use DHCP. Unfortunately, we have some clients that have less than stellar DNS servers in their networks and have ...
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6answers
2k views

Why am I getting long TCP connect latency on connect in a LAN (over a cross!)?

I am measuring a time of about 100-150 milliseconds from sending TCP SYN to getting SYN/ACK, between two linux computers connected to the same Cisco switch. Consider: The machines are very powerful, ...
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1answer
156 views

is it possible to use ms loop back adapter to setup local vlan

Is it possible to use Microsoft Loop back adapter to set up Lan connection between two computer which is logically isolated from the main network? 1st computer: has a regular ip stack 192.168.1.x ...
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291 views

What is a RP Paket in a tcpdump log?

I have a tcpdump log with the following entry: 14:53:31.428570 IP 10.4.65.65.16666 > 192.168.201.10.80: RP 587:687(100) ack 48545454154 win 0 My Problem is that i have never seen an RP paket ...
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2answers
95 views

Design for wire between server and access point and RF to endpoint device

We're about to design an inhouse industry network consisting basically of the following: 1 server connected via wire to up to 100 proprietary RF access points (basically embedded devices), which each ...
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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 ...
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2answers
385 views

I'm looking at sharing a printer over the internet, what are the implications?

Is it safe to NAT to the TCP/IP printer on the appropriate port in the router? Will I get unwanted documents from hackers or is this not a huge problem?
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2answers
6k views

TCP/IP packet loss network testing (in context of PingPlotter)

My question may be pretty basic TCP/IP / router based, but I need to couch it in terms of a Winpcap application pingplotter that I have used. One of the features I did use in my last place of work ...
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1answer
105 views

Multi-IP server: how do programs know which IP to use?

I recently tried adding second IP address to our server for various reasons and found that now when I check netstat -anob there are many programs/services listening and establishing connections to ...
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1answer
186 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 ...
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1answer
228 views

How to do MAC based one to one NAT on Linux?

I have a linux machine running ubuntu server with 2NICS (WAN and LAN). I want the LAN side machines to use the linux box as a gateway to get on the internet (WAN side). The only problem is that the ...
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3answers
573 views

Slow and fluctuating server network speeds in a new data center

We have a server running Windows storage server 2003 with: - an FTP server and - VMware Server running a VDS with apache (vds runs windows web 2003) This is in a data center and we just switched to a ...
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4answers
162 views

Is asymmetric latency common in practice?

This is a follow-on to a question posted on stack overflow about whether it is possible to determine the one-way latency of a point to point connection without using externally synchronized clocks - ...
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2answers
151 views

How does VPN software 'hijack' packets for tunneling?

My current mental model An application interacts with the operating system to produce an OSI model stack-based packet process - subsequent layers of encapsulation Somewhere along the line before the ...
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2answers
108 views

Thousands of port 25 connections

Tonight a few IP addresses made almost 2500 connections on port 25 of a mail server. 2500 is the max limit, and 50 or less simultaneous connections is normal. They did nothing once they made the ...
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2answers
2k views

Problems with MDNS flooding on port 5353 UDP

I am running into a big issue at a small network i manage. This network is an Apple network, with airport extremes, expresses, mac book pro's, imac's, ipads, iphones etc... I went to add something to ...
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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 ...
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1answer
80 views

Maintaining same TCP session, load balacing

With http live streaming (HLS) we need to deliver video segments one after other to the player to play them in a continuous fashion. Segments are present on many streaming servers and we would load ...
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3answers
1k views

Cannot ping host stale ARP cache?

I am having a strange issue with a Debian (Lenny/Linux 2.6.26-2-amd64) that has been driving me nuts. On some machines within my network I can ping the host in question just fine, other times I have ...
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1answer
823 views

Analysing tcp packet reordering problems

Our site is connect to the internet by a pair of lines which currently have a significant difference in latency. We have a suspicion that when we enable 'downstream bonding' on these lines (i.e. our ...
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1answer
75 views

Server with two default gateways won't listen on the second gateway

I am testing a redundant internet connection setup that works like this - I have a network segment, 192.168.80.X It has two gateways - 192.168.80.1 - a FW connected to a frame relay line ...
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1answer
134 views

Frequent interruptions of SSH connection to VPS

My SSH sessions die at what seem like random times - response will stop, and then a few seconds later PuTTY will pop up a message with, "Server unexpectedly closed network connection." It seems to ...
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1answer
290 views

TCP/IP connection to SQL Express works on HALF of the clients in a WORKGROUP

So far I have learned the following facts about Microsoft SQL Server Express, including version 2012, and earlier versions like 2008R2, and 2008, and for the most part all the way back to SQL Server ...
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1answer
214 views

Way to do basic WAN optimization between two Linux servers that splits single connection into multiple parallel ones? [closed]

There are utilities on Linux that allow you to work around WAN conditions which cause you to not be able to utilize your full bandwidth. They do this by performing multiple requests in parallel (for ...
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64 views

Why would a process be showing an outbound connection from a 169.254 address when there's no unconfigured adapter?

I have a system that has several network adapters, only one of which is enabled. That adapter has ipv4 only enabled and it has a single IP address. It was previously part of a team. The team was ...
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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. ...
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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 ...