0
votes
0answers
18 views

Linux message: Possible SYN flooding on port 25. Sending cookies

I have a Linux CentOS server online. At my console this message appeared: possible possible SYN flooding on port 25. Sending cookies. See SYN flood and SYN cookies. I have done an Apache JMeter ...
1
vote
1answer
34 views

Utility to monitor a TCP connection for drops

I found some similar questions, but not quite like this, so am going ahead and posting. I use a replication product at a client site. We are running a Windows 2003/2008 server environment. It is ...
-1
votes
1answer
22 views

How can my server announce its presence to everyone in the network [closed]

The situation is as follows. I want to have an application running on a server. All of the desktops in the company has to connect to it. But I do not want the IP address of the server to be hard coded ...
0
votes
0answers
26 views

Multipath tcp application-level performance measurement

I am working on a project related to Multipath tcp and I want to measure the goodput and the RTT at the application level. I don't want to use a traditional tool(netperf, iperf, ...) and I want to ...
0
votes
0answers
24 views

No response to ping of specific size

ping <anything> -s 473 does not receive a single reply. ping <anything> -s 476 works, as well as ping <anything> -s 472 but no size inbetween. What could be the reasons for ...
1
vote
1answer
31 views

Redirect ip to another page

i have a modem Dlink DSL-2730U i want to make this modem redirect some ip to another page or to another ip example : i have this ip : 123.456.7.9 i want to redirect it to 8.8.8.8 from ...
0
votes
0answers
14 views

Inconsistent connection to Websocket on embedded device

I am trying to set up a basic Websocket echo server on an embedded device. I'm testing the server through a very basic webpage, which simply connects upon load and sends a short message ("test") and ...
0
votes
1answer
54 views

Websocket handshake response not forwarded from TCP to client

I am trying to create a websocket server. I can see the websocket client's opening handhshake. My response to it is received by the client laptop (I can see this on wireshark). So the TCP connection ...
0
votes
0answers
14 views

Tons of connections to TCP 135 on another host on the LAN

I am facing a scenario where one server has tons of established connections to port 135 on the DB server on the same subnet. So when I do netstat -nap tcp, I got pages of pages followings, random ...
1
vote
1answer
167 views

How to send data to tcp server from command prompt [closed]

I am a java developer and quite aware of socket programming in java.I have a tcp server running my localmachine.I can write java codes for client and check communication between server and client.But ...
2
votes
1answer
62 views

Benchmark maximum number of TCP connections on Windows Server 2012

I am wrestling with deploying an application on Windows Server 2012. The problem is that after accepting about ~2000 TCP connections it fails to accept more. And I need much more. We have 8 cores, 16 ...
0
votes
1answer
30 views

Ethernet port re-transmission frequently

We have a laptop that uses its Ethernet port to connect to a device-local network, and wireless for Internet. Recently we installed Wireshark to diagnose some network problem. We found a lot of TCP ...
1
vote
1answer
49 views

How are ports and URI schemes handled by a tcp/ip server?

I am working with the lwip tcp/ip stack on an embedded device, and I'm trying to understand how it all works. I've been looking through the documentation and code, but I'm confused by how ports and ...
0
votes
1answer
28 views

How can I turn on ECN for Mac OSX?

I'd like to run some networking tests with Mac OSX 10.8 and using the ECN option. However I cannot find any documentation on how to configure it. Does anybody know how to alter Mac OSX TCP networking ...
0
votes
1answer
39 views

How to add code into the linux kernel?

I am studying how to analyse and evaluate the TCP/IP protocol stack of Linux. My goal is to study the performance of the tcp/ip protocol stack as a whole, to study the time cost of each layer and ...
1
vote
0answers
75 views

Iperf tests in reverse direction

I used iperf to measure the max throughput for TCP connection between two ubuntu machines. Both the machines were directly connected be means of a 1Gbps cable. When I performed iperf tests i obtained ...
0
votes
0answers
32 views

How to use netperf on specific NIC port?

I have two servers, SERVER and CLIENT and each server has its own onboard 1 GbE ports, and its own NIC with a 10 GbE port. SERVER and CLIENT are interconnected on both a 1 GbE switch (administrative ...
0
votes
0answers
20 views

Setting/clearing packet's TCP flags with iptables

I know iptables can match packets with certain TCP flags using --tcp-flags. But how do I set or clear some flags on a matched IPv4 packet?
-1
votes
2answers
172 views

Windows Server 2012 cannot access web sites

I have a Windows Server 2012 that has gone a little crazy in the last 24 hours. It can't access any websites, internal to the network or on the web. I can ping google.ca for example and it resolves ...
4
votes
3answers
901 views

How to force a process transmit over UDP instead of TCP?

I 'm running an ffserver process on a Linux machine, in order to achieve video streaming via ffmpeg. However, there is a delay on video streaming. On ffserver configuration file I define Port 8090. ...
0
votes
1answer
50 views

DNS Resolver for Windows over TCP

I know that DNS uses UDP with Port 53 for DNS queries. However, at my place sometimes UDP requests are blocked and DNS fails. I know that there is protocol for DNS over TCP and many public DNS servers ...
0
votes
0answers
27 views

UDP causing problems with other connections

I have implemented a file transfer program on Windows 64-bit platform using winsock API. I am using a 1Gbps connection. When I transfer files using TCP protocol, I am getting only 320 Mbps. when I ...
0
votes
2answers
42 views

TCP/IP minimal size

I am using a high level language on a PC to send a message via TCP/IP to a remote device which is an embedded device. I am sending relatively small messages (< 255 bytes). I must assume that there ...
4
votes
1answer
200 views

Why does writing IP addresses this alternate way work, and is there a practical use case for it? [duplicate]

Recently I saw an incorrectly typed telnet command, and I saw that "regular" numbers were interpreted to IP addresses. I tried this myself in Windows and the same behavior is shown there, so obviously ...
-1
votes
2answers
108 views

Is DNS query a UDP or TCP?

I know that when we first type an address on the URL and enter. The DNS query starts. I don't who initiates, but my guess is application will only initiate the DNS query. The DNS query already knows ...
0
votes
0answers
27 views

What impacts does RTT have on the behaviour of TCP?

How does round-trip time impact a TCP connection's behaviour? I know that the throughput of a connection with a high RTT is lower than the throughput of a connection with a low RTT but how does RTT ...
0
votes
1answer
74 views

How to calculate TCP network speed

So basically this is an easy question, but not an easy answer. How do i calculate the download and upload speed in order to make program this in c#? I'm not sure how to take latency into account. I ...
1
vote
1answer
1k views

Communication possible between 192.168.0.x and 192.168.1.x?

I have a problem I encounter on a regular basis. I have an access point with a fixed 192.168.0.x IP address. My network is 192.168.1.x. The problem is when I plug the access point into my network, it ...
0
votes
1answer
64 views

Throughput decreases after MTU 5000

I am trying to test throughput between two computers directly connected through 1 GbE and testing with iperf. I am getting a throughput around 980Mbps when MTU is between 5000 and 5050, however it ...
1
vote
1answer
131 views

Is it possible to create a WiFi TCP socket between two computers in a LAN?

Here is our setup. The FEZ Cobra II (WiFi) Single Board Computer with a RS9110-N-11-22-04 WiFi module and running the .NETMF 4.2 The documentation says that: This allows for real "Socket" ...
0
votes
2answers
74 views

Can using UDP and OpenVPN lead to file corruption?

I know with TCP that it always checks your files to ensure nothing got fragmented or lost or destroyed. So if I use UDP for OpenVPN to download files or access an internal network, does that mean I ...
0
votes
2answers
58 views

Capture packets from other machines in local network

Is it possible to capture packets from other local machines on my Mac? They are primarily all wireless as well, if that makes it any easier.
1
vote
0answers
57 views

Delete Hung TCP Sessions with SNMP

What I am trying to do, and failing horribly, is to close a TCP connection... I am trying to do this via SNMP and the functionality that is provided in the TCP MIB. First, I look at all the ...
0
votes
0answers
16 views

How to keep socket visible after closing the connection?

Is it possible to configure Linux to keep a tcp connection visible for netstat/lsof after being closed? (doesn't matter the connection state). I need to detect it with netstat/lsof but if the ...
1
vote
0answers
89 views

Windows 7 / PuTTY drop IPv6 TCP connections on brief outages

This is an IPv6-version of the following question: Why Windows 7 / PuTTY drop TCP connections even on very brief outages? After moving from IPv4 to IPv6, I've noticed that my IPv6 connections would ...
1
vote
1answer
572 views

What's up with port 8080 on my OSX box?

I thought a web server process I brought up was listening on localhost:8080, and tried to connect to it, but kept getting connection reset errors. As it turns out, I was mistaken and my process was ...
0
votes
0answers
16 views

TCP behavior in microsoft products

What happens when a TCP SYN segment is received on a closed port? Does windows send a RST or it just ignores it?
3
votes
1answer
321 views

SYN-ACK not received

On a standard TCP connection between server and client, I have this issue: the SYN-ACK is not received from the client, while it is sent from the server. I could see this on Wireshark from both server ...
1
vote
1answer
529 views

Network issues, resolving host

My network connection randomly drops for a 5 minutes or so when I'm online. It always happens when I boot up my computer. I can tell because it says:resolving host in Chrome and I can't ping any ...
1
vote
1answer
44 views

How to configure the physical machine and virtual machine?

If I want to transfer data between the physical machine (windows operating system) and virtual machine (Linux real time operating system). Could anyone please explain about configuring the data ...
-1
votes
1answer
29 views

How does an ADSL modem tell which local client to associate with each response from a server?

Does an ADSL modem generate a random string for each request I make and when response comes it directs it to my computer (but not to my phone)?
0
votes
0answers
25 views

Switching ethernet interfaces in Fedora

I am working on a computer which has two gigabit ethernet interfaces. This is the current configuration: PORT 1 (INTERNET) PORT 2 (SPP) Port 1 connects my computer to the internet whereas ...
2
votes
3answers
146 views

Is the same port acting as both client and server?

i find something strange in this netstat output. the output is taken using netstat -a -n -o -p TCP command on win 7. Proto Local Address Foreign Address State PID TCP ...
0
votes
0answers
442 views

connect to a serial device via TCP socket

My setup is this: serial device ttyUSB0 connected to laptop A software that opens TCP socket to listen and write to, also runs on laptop A (linux) My goal is to pipe data from/to serial device ...
0
votes
2answers
2k views

what is type of ICMP packets? TCP or UDP

ping packets is a type of ICMP packets.Is there any relation between ICMP with TCP.In other can we guaranty their arrival in the network I want to know ICMP packets in the network is tcp or udp or ...
-5
votes
2answers
95 views

Is there a way to pause/resume particular TCP connection?

I'm playing online game that matches me against random players. I found out that when I unplug my Ethernet cable, I have a minute to decide do I want this match to count. If things go wrong, I just ...
2
votes
3answers
946 views

Can't connect to SSH server using WAN IP address [duplicate]

I have an SSH server behind a NAT router. Machines on the same (NAT'd) network as the SSH server can only connect to the SSH server using the LAN IP, not the WAN IP. Why? My network looks like this: ...
0
votes
1answer
370 views

Ubuntu openVPN TCP no internet, UDP works. Win7 works on both TCP/UDP with same settings

I've recently purchased a VPN service which I'm connecting to with openVPN. On Windows 7 I can connect on both UDP and TCP settings, but when I'm trying the same thing on Ubuntu 13.04, it gives me ...
0
votes
0answers
225 views

Can't telnet: TCP connection doesn't get established

I am having issues with telnet from a machine. TCP connection is not getting established. SYN gets sent out and SYN_ACK comes back but not sure why the ACK is not getting sent back. I am guessing ...
0
votes
1answer
136 views

Using and testing UDP data over the internet [duplicate]

I have a GSM modem that sends data via UDP (it appears) I have configured it to send all data to my public IP address over the internet but no data is arriving at my end so I need to troubleshoot. I ...