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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.

Dear experts,

I have a Window 2012 R2 server running DNS, DHCP, and AD DS and a sonicwall firewall. For some reason that my DNS server is not working. When I look at my network connection from Window 7, I can see that IPv4 Default Gateway is 192.168.1.1, IPv4 DHCP server is on 192.168.1.30 but IPv DNS server is on 68.x.x.x It is not pointing to my DNS which should be the same as the DHCP server (192.168.1.30). I am not sure what went wrong as in if there is a mis-configuration in sonicwall firewall/router or the DNS server at 192.168.1.30.

I can see my client PC is not talking to the local DNS server 192.168.1.30 but instead on 68.x.x.x my ISP. Is there a way to configure in order to ensure my client PC will ask my local DNS first if no information can be found then forward to the DNS of my ISP and so forth?  I have set my TCP/IPv4 to Obtain an IP address automatically and Obtain DNS server address automatically. Is there a way to set obtain IP and DNS server automatically rather than set those to static?
0
Striggling with dhcp on linux.  
Need to know scope range, reservations, lease hours/days, % scope used, etc.

Here is what I have:   can can you take  apeek and help with commands?

# File managed by Chef

# set this to store vendor strings.
set vendor-string = option vendor-class-identifier;

allow booting;
allow bootp;
allow unknown-clients;
allow client-updates;

authoritative ;
ddns-domainname "corp.companyname.com.";
ddns-update-style interim;
ddns-updates on;
default-lease-time 6400;
filename "pxelinux.0";
max-lease-time 86400;
next-server 10.x.x.x;
one-lease-per-client true;
ping-check true;
update-static-leases true;

option domain-name "corp.companyname.com";
option domain-name-servers 10.x.x.x, 8.8.8.8;
option domain-search "corp.companyname.com", "i.companyname.com", "someothername";
option host-name  = binary-to-ascii (16, 8, "-", substring (hardware, 1, 6));




zone corp.companyname.com {
 primary 10.x.x.x;
 # uses name format could use IP address format
}
# zone 42.10.in-addr.arpa {
#  primary serverhostname;
# }

include "/etc/dhcp/groups.d/list.conf";
include "/etc/dhcp/subnets.d/list.conf";
include "/etc/dhcp/hosts.d/list.conf";
~                                                                                                                                          
~                                                                                                                                          
~     …
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We’re using a SonicWall TZ-215 firewall.  Our LAN X0 port is setup as 192.168.0.1—254, with 192.168.0.2 setup as the gateway, 255.255.255.0 as the subnet.  

We’re getting VoIP phones, and the vendor is setting them up with static addresses between 192.168.1.100—200, subnet 255.255.255.0.  How do I configure the SonicWall to get the phones to access the 192.168.0.2 gateway?  (X3—X6 interfaces are unused on the SonicWall, if needed for the solution)
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I can see in a packet X-Forwarded-For info such that I can see the original source
address of the packet sent to the front end of my load balancer. Now if I am using
wireshark and I only wanted to see packets with a specific x-forwarded-for value,
how could I do that?
0
We need to get Speed and Duplex of networked machine via CMD or powershell.   Is there a way to do this, and to get the information, without looking at the switch?
0
When I go to the https://dmarcguide.globalcyberalliance.org/#/ website and type in the email domain name of my organization the SPF & DKIM results pass but for the DMARC test I receive a message that says "Thank you for getting started with DMARC. You are currently at the lowest level and receiving reports, which is a great starting point. Please make sure to review the reports, make the appropriate adjustments, and move to either quarantine or reject soon. Additional information about reporting tools can be found here" (see the second screenshot below).

When I click on here I am taken to this website https://dmarc.globalcyberalliance.org/dmarc-reporting-key-benefits-takeaways/.

What values do I need to change or what settings do I need to change within my external DNS server records so that I will pass the DMARC test for this globalcyberalliance.org website?

I currently have this TXT record setup within my public DNS records for DMARC:

_dmarc.domain.com.      3600      IN      TXT      "v=DMARC1; p=none; rua=mailto:postmaster@domain.com; ruf=mailto:postmaster@domain.com"

DMARC-TXT-Record
PLEASE NOTE: The actual domain name has been replaced with the word domain above and has been whited out in the screenshot for privacy purposes.

Domain results
0
What is the correct Time to Live (TTL) value that an email domain's MX record should be set to?
0
I am receiving intermittent issues on a client server. After a while, users cannot access the internet or internal servers. Unfortunately, I am not on site and only have access to the logs as we need to restart the server before I can get there to minimise down time for all users.

Once the server is restarted, all users can access the internet/internal servers/share drives etc.

This has only come up over the couple of months randomly. Previously the DNS servers on the server had another IP which is the virtual server NIC (nic 2) and the TCP/IP V4 DNS had 127.0.0.1. The 169.x.x.x has been removed and the 127.0.0.1 has been changed to 192.168.1.1.

Would really appreciate what else I should be looking at as this has me stumped. Are there any ports on the firewall that need to explicitly be open?

The errors at the times of the issue commencing is Netlogon error 5774 entries. I have copied one below however have slightly changed the DNS record of the internal domain name. The IP Address 192.168.1.1 is the Server 2012 R2 DC. It is the only one on the network.

The dynamic registration of the DNS record 'DomainDnsZones.DOMAINNAME.local. 600 IN A 192.168.1.1' failed on the following DNS server:  

DNS server IP address: 192.168.1.1
Returned Response Code (RCODE): 0
Returned Status Code: 10054  

For computers and users to locate this domain controller, this record must be registered in DNS.  

USER ACTION  
Determine what might have caused this failure, …
0
Dear experts,

I came across a situation where I wish to create two subnets as in 192.168.1.1 and 192.169.2.1

The 192.168.1.1 will be my main network which will contains most of the PCs, printers, etc....

The 192.168.2.1 will be my wifi network which all wireless connections such as phones, scanners, etc...

Here is the situation:

1. only have 1 switch with 48 ports (can be configured)
2. one sonicwall firewall  4 ports in back(can be configured)
3. allow the two networks to talk to one another as in if I have a PC in 192.168.1.x and wish to access a wifi device in 192.168.2.x

Here are the things that I wish to get answered and accomplished:
1. I wish to know what will be the "BEST and SIMPLE" configuration to accomplish this task. Thanks!
2. Is it possible to connect all devices into a single switch (the 48 port switch) and have combination of networks like 192.168.1.x and 192.168.2.x together without utilizing the VLAN?
1
I want an Button to form that will display my computer's IP address,, how can I do this? Thanks in advance.
0
I have an VPN trough 2 sites. but i can´t configure the printers through IP.

I open the cmd and ping the IP correctly... but when i try to configure a printer of the other site with the IP, it doen`t work.

For instance:

i can ping a printer in 192.168.0.200 but i can't install this printer on a server 2016 via this IP.

Any tips?
0
Are other ISPs besides Comcast able to use Comcast's DNS server addresses of 75.75.75.75 & 75.75.76.76?

An organization I am working for has switched over to using Comcast fiber optics as its primary internet service provider (ISP). We also have a second internet service provider (Etheric Networks (https://ethericnetworks.com/) which provides satellite dish based internet services.

Our internet service is set up in a failover configuration using a SonicWALL TZ600 router so that if our primary Comcast fiber optic internet service fails then our internet service will automatically switch over to Etheric until the Comast fiber optic service is restored.

We would like to continue to use the static external DNS server addresses of 75.75.75.75 and 75.75.76.76 in place if our internet service ever switches over to Etheric should the Comcast fiber optic internet service become unavailable.

Our question is if our internet service switches over to using the Etheric internet service will the external IP DNS server addresses of 75.75.75.75 and 75.75.76.76 still be valid and provide timely DNS name resolution?

Or is there a different type of method we should be using to handle our internet service and DNS name resolution switch over?
0
I need a script that can disable IPV6 remotely, the powershell script I had did not work. The reason being is because when I remote into a machine for some reason opening the network settings as admin does not work. :(
0
I was reading as below

TCP - is a transport layer protocol. It works over an IP network
HTTP - is an application protocol. It works using TCP on an IP network

i was not clear. Does HTTP also uses HTTP
what other protocols there in networking.

nay good link, resources or free video tutorial to understand clearly these things?
please advise
0
I inherited a Class B network years ago and am just now wanting to do a major overhaul.  Currently the LAN network is 10.1.0.0/16.  It is currently just a flat network with servers and clients dispersed throughout.  I want to segment the network into the following categories: Servers (25ea now), Workstations (100ea now), Printers (30ea now), Utility devices (20ea now).  All of our wireless clients are connected on the outside of the firewall and are outside the scope of this question.  Our firewall is a WatchGuard device.

Should I rework the ip address scheme?  If so, can someone layout an example of what I should do?

thanks!
Lance
0
my network is as follows:

Comcast 10.1.10.1

Sonic Wall - 10.1.10.2 (gateway 192.168.1.1)


Just double checking, I want the SonicWALL subnet to be private.  I am a little concerned because when I am on a workstation behind the sonic wall I can ping the Comcast gateway, and navigate to the admin portal.

However, when I am directly plugged into the Comcast gateway I cannot ping the 1.1 gateway subnet.  So the SonicWALL subnet is not visible to the main comcast network.  Is my network setup and secured as intended?
0
Hello Experts,

We have an application which is login on CentOS 6.8 64 bit (GUI Interface) & after login generate tcp port 50000 for make connection with user.
Behind that port there are many connection connected with different-different IP (192.168.207.11, 207.12, 207.13) & user name (user1, user2, user3):

Example Output:-
[root@CC ~]# lsof -i :50000
COMMAND    PID USER   FD   TYPE DEVICE SIZE/OFF NODE NAME
TCPServer 3647 rajat  245u  IPv4 156532      0t0  TCP 192.168.207.125:50000->192.168.207.15:49277 (ESTABLISHED)
TCPServer 3647 rajat  261u  IPv4  23354      0t0  TCP *:50000 (LISTEN)
TCPServer 3647 rajat  387u  IPv4  24955      0t0  TCP 192.168.207.125:50000->192.168.207.13:49271 (ESTABLISHED)

From this cmd i only check which IP is connected behind port 50000, but i want to check user name also. Please suggest.
0
Hi,

Is there such an application that can scan ports between two devices so see there which ports are open/closed/listening?

We have two devices, each one on different sides of wireless link, on the same network, and we wish to confirm there is no issue of ports not working.

The type of app I am think is iperf but for ports.

Thanks,
Col
0
This morning when I got to work a couple of machines could not access the internet, including my own. The only common thing is that they have all got static IP addresses for RDC connections.

main subnet => 192.168.16.1/21
DHCP scope => 192.168.18.10 - 192.168.18.255

my static IP => 192.168.19.3

On the PC's which have a static address if i change them to DHCP everything works. If they are static they are not able to access anything external. Internal Sites work fine. DNS lookups work fine for both internal and external sites.

I have tried getting a dhcp address on my PC, then setting the exact same IP address manually and see the same restrictive behaviour. Everything was fine yesterday evening when we left, nothing has been changed. i cant see any updates have occurred. i have checked router settings and rebooted several times. still no joy.

Any Help would be appreciated.

Thanks

Michael
0
Hello Experts,
I just installed sonicwall tz400w and everthing is going well except printer. Printer disconnect automatically after few minutes. I have to connect them manually again and again. I am using commercial printer by konica minolta and i use fiery app on Konica. Its working fine without the firewall.  Please help
0
We use a service to route calls for our call center. There are about 100 call center agents and everyday, four or five will have trouble launching the soft phone application. We connect to the call manager and soft phone system via and MPLS.

Sometimes restarting the PC fixes it. Sometimes resetting the browser fixes it, sometimes disabling / re-enabling the NIC fixes it. Sometimes it magically fixes itself.

The attached packet capture image from Wireshark typifies what a TCP stream looks like from a PC experiencing  a failed application launch.

NOTE: In the attached file, the TCP RST flag is not always seen. Many times I only see the TCP re-transmissions or TCP SEQ Out Of Order.

Questions 1: Am I right to believe my problem is, either a reset is being thrown or the other side stops responding for some reason, hense the re-transmissions

Since this is over an MPLS, I am not able to get a capture from the other side.

Question 1. What troubleshooting steps should I take to identify why I am getting these re-transmission, and or Resets.

Question 2: Is it possible that some traffic might be routing out the MPLS, while other is getting lost in the network? If this were possible, and I wanted to capture the packets on the Switch, would I SPAN the both the interface connected to the PC and the Interface connected to the router, or just the router?

Note: I don't have trouble logging into the portal, I have trouble launching the softphone, which uses a browser …
0
I have a client/server TCP .Net application. I am getting exceptions on NetStream.Read or Write operations, no data received, if there is a delay of about 10 minutes or longer.

The client app contacts the server. The client may send blobs (many reads and writes back and forth for each blob) of data to the server. The server may then send blobs of data back to the client. There can be a processing delay before each sent blob. Everything works with even large blobs going back and forth. The problem occurs when the processing delay before starting to send a blob becomes around 10 minutes.  For example: Connect, client sends a blob, server process for about 10 minutes, server tries to send a blob, error on first TCP write (read error on first TCP read on client). This problem does not occur if the client and server are on the same LAN. It only occurs when a client outside of the LAN connects through the Router via port forwarding to the server.

Is there some kind of router timeout setting I should be considering? Or maybe an "idling" parameter to tell the TCP connection to stay active for long periods of time?
0
For some reason this virtual machine running Windows 2003 Std SP2 started to bluescreen and reboot non-stop, it will stay up for a few minutes and them it crashes, the mini dump contains the following. This server is a stand-alone server. Any ideas will be welcome.


==================================================
Dump File         : Mini120817-08.dmp
Crash Time        : 12/8/2017 7:29:59 PM
Bug Check String  : IRQL_NOT_LESS_OR_EQUAL
Bug Check Code    : 0x0000000a
Parameter 1       : 0x00000000
Parameter 2       : 0xd000001b
Parameter 3       : 0x00000001
Parameter 4       : 0x808312e7
Caused By Driver  : tcpip.sys
Caused By Address : tcpip.sys+1ce7a
File Description  : TCP/IP Protocol Driver
Product Name      : Microsoft® Windows® Operating System
Company           : Microsoft Corporation
File Version      : 5.2.3790.4573 (srv03_sp2_gdr.090815-0925)
Processor         : 32-bit
Crash Address     : ntkrnlpa.exe+8c9eb
Stack Address 1   : ntkrnlpa.exe+312e7
Stack Address 2   : ntkrnlpa.exe+28191
Stack Address 3   : afd.sys+153f
Computer Name     :
Full Path         : C:\WINDOWS\Minidump\Mini120817-08.dmp
Processors Count  : 8
Major Version     : 15
Minor Version     : 3790
Dump File Size    : 85,344
Dump File Time    : 12/8/2017 7:31:29 PM
==================================================
0
Hi all - Will try to explain carefully ... thanks for reading ...  

My problem:
I am experiencing intermittent issues when watching a movie, which is a 7GB file on a local network drive of mine. Downstairs all works fine. Upstairs, when the issue occurs, the movie will play for 10 seconds, then I get a wait-icon (hourglass or what have you) for about 10 second, back & forth over & over.
Sometimes it behaves this way, and other times is perfect.

My Network:
Fast Ethernet service (Time Warner) from the street into my Modem. All over Downstairs it clocks at 110 Mb download and 13 Mb upload, using speedtest.net.
UPSTAIRS I have an Apple Airport Express, setup as a Bridge "Extend an existing network", which worked fine downstairs until I moved it upstairs.  Then connected to that is an Apple TV connected wirelessly, using the same netwk name (SSID).  It clocks at 30 Mb down & 8Mb up, way slower than Downstairs, but I thought would still be fast enough to watch a movie without speed issues.

Note that the data/movie is coming over my LAN ... that I have saved on a local network drive in my house. It is *not* being streamed from any services!  The 7GB Movie is on an ext hard drive plugged directly into the Airport Extreme Base Station.

Can anyone suggest how to troubleshoot this? It's been a long time since I broke a perfectly working network and had to do this!  I am thinking:
- Get a meter or Util to measure exact bandwidth/signal strength?
- Change to use …
0
When a client initiates an SFTP upload to a server - is the size of the file to be coming included in the early part of the conversation? It would be helpful to know in some instances. Thank you.
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.

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