TCP/IP

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Transmission Control Protocol/Internet Protocol (TCP/IP) is the set of networking protocols that define end-to-end connectivity specifying how data should be packeted, addressed, transmitted, routed and received at the destination. This functionality is organized into four abstraction layers which are used to sort all related protocols according to the scope of networking involved.

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We just switched to a different ISP provider a few days ago. Since then, there have been several Bad Address entries in the DHCP server (Windows server 2012). After deleting them, they'll appear again in an hour. Their Mac addresses are not shown in the address lease.

I used the DHCPFind to check if there's any other DHCP server on the network. The result is attached.

How do I find out what device(s) is causing the issue? Or How to fix this issue?
DHCPFindResult.JPG
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Dear EE,

I have found warning at DB server when user has reported Application dis-connectivity.
 
1)  User reported Application Dis-connectivity Error as attached.
SQL Error

2) We investigate the issue and look in to the Event logs and found below WARNING. Event Id : 4227

TCP/IP failed to establish an outgoing connection because the selected local endpoint was recently used to connect to the same remote endpoint. This error typically occurs when outgoing connections are opened and closed at a high rate, causing all available local ports to be used and forcing TCP/IP to reuse a local port for an outgoing connection. To minimize the risk of data corruption, the TCP/IP standard requires a minimum time period to elapse between successive connections from a given local endpoint to a given remote endpoint.


Please confirm will user application error is due to this above error.

Thanks
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The DFS Replication service failed to contact domain controller  to access configuration information. Replication is stopped. The service will try again during the next configuration polling cycle, which will occur in 60 minutes. This event can be caused by TCP/IP connectivity, firewall, Active Directory Domain Services, or DNS issues.
 
Additional Information:
Error: 160 (One or more arguments are not correct.)
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I am having problem with using arpspoof on my kali linux box.  i am receiving the following error " arpspoof: couldn't arp for host 10.10.9.5(windows host). I am able to ping to all my network devices and SVI's. I have bulilt out my own Network lab that have cisco routers, swithches, and firewalls. All my devices are receiving ip's from my DHCP server, and able to get on the internet. But for some strange reason the kali linux box arp table isn't populating and it's showing only  10.10.6.1 (which is the SVI), and the cisco switch arp table is populated.  

Below is the command Im using.

arpspoof -i eth0 -t 10.10.9.5 10.10.9.1

I have 4 vlans in my network (User's, Server's, Management,and kali)

10.10.9.x/24= users
10.10.8.x/24= servers
10.10.7.x/24= managment
10.10.6.x= kali
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Hi!  anyone have any luck with a "TELNET" like connection with MS ACCESS?    I send simple text commands to a connected unit via TELNET.    By TELNET I mean using a communications application that converses with a connected device via IP address.     Something like sending "readbuffer01" and a response like "0,00.4,2" is returned by the conneted device.   I do this over a TELNET application like Tera Term set up for IP of the connected device xxx.xxx.xxx.xxx format for IP and TCP/IP port 3602 emulating a VT100 terminal.   Any way that ACCESS can send commands and listen for a response like these terminal programs.   I am basically trying to automate data collection over the tcp/ip connection and store in a form/table.

Thanks!
Brian
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Hi Experts,
How to grep connected tcp IP & Port connection then forcefully kill using batch.

example;-
netstat -a output is

Active Connections

  Proto    Local Address                        Foreign Address                State
  TCP       192.168.1.101:49366            192.168.1.55:65000          ESTABLISHED
  TCP       192.168.1.101:49475            192.168.1.55:64000          ESTABLISHED
  TCP       192.168.1.101:49384            192.168.1.55:63500          ESTABLISHED
  TCP       192.168.1.101:49396            192.168.1.55:22                 ESTABLISHED

Need to forcefully kill all TCP connection which is connected with 192.168.1.55
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I bring my (Windows 10 Pro) laptop around to do support in a few different networks - some with DHCP and some where a fixed IP-address is needed. Have tried to find a way to make shortcuts to set the fixed addresses (or set the network adapter back to dhcp), but haven't found a way to do it. Thinking of commands in a batch-file. Any suggestions?

-Olaf-
1
Can someone explain to me where consensus algorithms fit within the TCP/IP model?  Let use Raft as an example.  Does it use multicast?  Does it use it's own transport number or TCP/UDP?  Does it live on the application layer?

Thanks
0
Hello Experts,
Seemingly out of the blue (starting July 29th), though possibly corresponding with installing VMware Tools on the server (7/22), or, less likely I think, updating our ERP software including telnet server (7/21) and OS updates (7/21 - see attached), our Server 2012 R2 VM has been acting up.

I have been rebooting a telnet server service daily for two years+ to kick out clients that didn't log out and had their then sessions hang, which frees up licenses for new clients to log on in the morning. Recently, this has caused the server to not accept new connections on port 23. Nothing seems to fix it except for an OS reboot. The corresponding message in the Event Viewer is from AFD:

Closing a TCP socket with local port number 23 in process 16584 is taking longer than expected. The local port number may not be available until the close operation is completed. This happens typically due to misbehaving network drivers. Ensure latest updates are installed for Windows and any third-party networking software including NIC drivers, firewalls, or other security products.

Open in new window


This happens reliably now every time the telnet service is restarted. The process ID corresponds to the telnet server. Killing the process (that was restarted initially and caused this error) does not then allow connections on 23 - the OS must be rebooted. Disabling and then enabling the network adapter does not help. I reinstalled VMware tools which did not help.

Another error from Tcpip may be related started happening about a week later (8/7) and has been occurring daily or up to six times a day since:


Open in new window

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Cisco Network Question:  2 vlans and one Internet connection

I need to set up a guest network for access to the Internet-only.  The network configuration is:
-  COX Internet
-  RTR_FW: Meraki MX64
-  Core_Switch: WS-C2960X-48FPD_L:  LAN-base
-  Distribution_Switches: WS-C3560CG-8PC-S: IP-base

We presently have one external IPv4 address and use 192.168.168.0/24 internally for operations.

The 2960X is a layer 3 capable switch.

Is there a way to route another network VLAN, something like 172.16.168.0/24, to the Meraki RTR Internet connection.  The Meraki is presently port mapping the external address to the 192.168.168.0/24 network with the Default router of 192.168.168.1.  I used a trunk to the Meraki RTR-FW from the 2960X and it works....

Or do I need to add a RTR and use two virtual interfaces?
0
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Hello,
I would like to convert HTTP streaming HLS  to UDP or RTP, I  have tried VLC  and it works only in windows 10, does anyone  have any other software example that is validated  and is working properly?

Thanks
0
Hi All,

i need to listen on port for testing on a windows server. Do anyone know of a utiltiy? i used one before however unfortunetely i didnt keep a note of it.

Regards,
kay
0
Today we faced the Email Delay issue on Exchange environment. Emails were delivering with 5 to 7 minutes delay. On investigation, we found following errors on server. It appears from the first error there could be some connectivity issue between the Exchange servers, but both the servers are located on same chassis, the chances of connectivity issue is very low. After restart the issue gone it also shows there was no connectivity issue. What could be the issue?

Error on Server Queue:
{LED=441 4.4.1 Error encountered while communicating with primary target IP address: "Failed to connect. Winsock error code: 10048, Win32 error code: 10048. "Attempted failover to alternate host, but that did not succeed. Either there are no alternate hosts, or deliver failed to all alternate hosts. The last endpoint attempted was x.x.x.x:475]

Warning on Server Log:
TCP/IP failed to establish an outgoing connection because the selected local endpoint was recently used to connect to the same remote endpoint. This error typically occurs when outgoing connections are opened and closed at a high rate, causing all available local ports to be used and forcing TCP/IP to reuse a local port for an outgoing connection. To minimize the risk of data corruption, the TCP/IP standard requires a minimum time period to elapse between successive connections from a given local endpoint to a given remote endpoint.
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I had this question after viewing Need to kill an application that is auto starting on Windows CE 5.0.

I have a remote device running Windows Embedded CE 6.   I would like to add some bench automation to this unit, but like most target devices ti has an autostart routine that puts an app on a touch screen with limited functions.    I am confident I can get the automation I need if I can only poke around in the file system of the target device.   I am trying to connect to the device remotely with a Windows10 machine, so activesync is out.  I did try a windows XP machine and activesync failed, so the target device is not set up for that.   That leaves TCP/IP I guess and a connection with Visual Studio tools?   Is there a better tool?   VS requires that I install Corecon files to the target, but if I could install files to the target, I would not need Visual Studios.....  The unit can be attached with OEM software to run remotely as well as firmware updates are installed via USB connection, so I am pretty sure there is an agent installed to the target that allows this.   The unit installs to devices under Windows10 as "USB Remote NDIS Network Device".  I apologize for my novice approach here, but I am more of a hardware gy than software.   I am willing to hire this hel pout if anyone knows a contractor that works with embedded windows.     Thanks so much for reading!!

Brian
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How can I completely disable IPv6 from all network adapters on a Windows 7 Pro. computer?  The use this method to roll-out that configuration change to hundreds of computers?  Is there perhaps a script?

What I am looking for is to disable or un-check the ipv6 settings.

ipv6_1
I want it to be grey'd out or disabled.

ipv6_2
According to web page: https://techjourney.net/disable-turn-off-ipv6-support-in-windows-10-8-1-8-7-vista/

I have tried opening a command prompt as administrator and running
reg add "HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\Tcpip6\Parameters" /v DisabledComponents /t REG_DWORD /d 0x000000FF /f

Open in new window


But after I run this command I think IPv6 is disabled partly; but, I still see the check mark on the adapters indicating that it is still enabled.  

Question1: How can I disable the ipv6 for all adapters on a windows 7 Pro. PC?  My manager specifically asked me to do the un-check box, to make it look disabled.

Question2:  How can I use that method for a mass deployment to change the config on hundreds of devices?

Question3:  How can I verify that IPv6 is indeed disabled?

Before the registry changes, if I ran an ipconfig all, under "Ethernet adapter Local Area Connection"  I saw
IPv4 Address. . . . . . . . . . . :  ###.##.##.###
Then I saw
DHCPv6 Client DUID. . . . . . . . : ##-##-##-##-##-##-##-##-##-##-##-##-##-##

After the Registry changes, I do not see any reference to DHCPv6 Client DUID. . . . . . . . : ##-##-##-##-##-##-##-##-##-##-##-##-##-##
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Hi... Can anyone tell me what is this Simple Network Audio Protocol running on port 4752 ? Thanks
0
In the environment I am supporting for NGO's there are 2 Exchange Servers, an Exchange 2003 and an Exchange 2010 Server. On the Exchange 2010 Server since few days the router address 192.168.1.1 is added to the IP Block List on the Hub Transport Server. Even after disabling IP Block Listing on the Organization Level the router address is added regularly to the IP Block List within Hub Transport on Server Configuration Level. Any ideas how to prevent this. Blocking 192.168.1.1 does really block complete incoming mail traffic.
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Hello,

I started receiving TCPIP Event ID 4227 on two servers.  One server is an SBS 2011 domain controller and the other one is a Server 2016 Standard virtual machine on completely different hardware that only hosts a reporting software program.  These errors will occur at completely different times on each server so they don't seem to be related to one another at all.  The SBS 2011 server is running on it's own physical hardware, and the Server 2016 server is a virtual machine on a Hyper-V host which also has 6 other server virtual machines that are not experiencing this problem.

For troubleshooting, I have set the 'TcpTimedWaitDelay' to 30 in the registry on both servers and that did not fix the error.  I have also set up a script to run a netstat and get-process capture exactly when the error is logged in Event Viewer and I have collected the logs which are attached.  When looking through those logs I cannot determine what the issue really is since it doesn't seem to be related to the 'TcpTimedWaitDelay' setting.

At this time the error doesn't seem to be affecting any functionality on either server so I'm not sure how concerning this really is.

Any information is appreciated and if you need any further clarification on anything please let me know.

Thank you
SBS_2011_netstat.txt
Server_2016_netstat.txt
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Wired users getting 192.168.1.x IP address.  Instead of 10.10.x.x
Not sure what happened.   Not all the users tho.  Any ideas?
ipconfig /renew /release not helping.  
Need some help troubleshooting.
0
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Hi Expperts,

Using PHP, JS, and/or jQuery, is it possible to detect if the user is using their registered device.

I think that every device world-wide has a unique MAC Address, so I guess maybe my question is how to read the MAC address? However, not of any modem or router, but of the endpoint device (ie-computer, phone or tablet)?

Thank you.
0
Hi All,

I had capture the packet within our intranet where I place the sniffing tool at core switch to only capture conversation between all client to one server. I had observer the almost packet was captured is TCP SYN/ACK packet and TCP RST packet. The TCP SYN packet only below then 10% of captured packet. Its is abnormal in happen in this conversation?
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We recently changed a client's subnet from 192.168.1.x to 192.168.71.x.  All is fine, except that we neglected to change one of their devices to the 71.x subnet.  

We're remote now.  If we were onsite, we could change a computer to 192.168.1.x, connect to the device, and change its IP to 192.168.71.x,, then change the computer back.  But we're remote.  

If we change that computer's IP to 192.168.1.x, we lose internet connectivity.  

Is there a way we can still change the computer's IP to 192.168.1.x, but still use the default gateway of 192.168.71.1 to get to the device?  It's looking like we may have to go onsite to do this...

This is a very simple LAN; SOHO router/firewall.

Thanks!
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I have two sites, both of which are connected to an MPLS that provides the VOIP and site-to-site data communications. The main site has dedicated internet (ASA 5520 and 2800) and is where the other site goes through via the MPLS. All of this is on the private side.

Both sites have regular 100MB/s cable internet for the public Wi-Fi in addition to the EOF/MPLS.

I want to add some redundancy for both locations in the event the MPLS or internet at the main site goes down and utilize the existing public cable internet service.

Looking for some suggestions for failover, using existing equipment or minimal equipment for site-to-site VPN connections. Not too worried if I cannot keep the voice traffic running, mainly a data/internet issue.

Thank you in advance.
0
hi,
dns3.jpgps assist why can't change dns ip address and apply register dns settings.
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Hi

I'm having issues with Cisco Any connect VPN client not allowing remote connections, specifically ports 139-445.  Running port query is showing that there are some ports open but not ones for the IP address assigned to the virtual network adaptor.

We have the old Cisco vpn adaptor running and those ports are ok.

Ideas?

Thanks
0

TCP/IP

11K

Solutions

17K

Contributors

Transmission Control Protocol/Internet Protocol (TCP/IP) is the set of networking protocols that define end-to-end connectivity specifying how data should be packeted, addressed, transmitted, routed and received at the destination. This functionality is organized into four abstraction layers which are used to sort all related protocols according to the scope of networking involved.