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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I tried the below code and it showing output like SSH-2.0-OpenSSH_5.3 that means connected i hope.

 declare c  utl_tcp.connection;  -- TCP/IP connection to the Web server ret_val pls_integer;
 BEGIN c := utl_tcp.open_connection(remote_host => 'ftp.******.******.com'
                                   ,remote_port =>  21 ,charset => 'US7ASCII' --                              
                                   ,wallet_path     => '****************' --                              
                                   ,wallet_password => '**********' );  -- open connection
--  ret_val := utl_tcp.write_line(c, 'GET / HTTP/1.0');    -- send HTTP request
ret_val := utl_tcp.write_line(c);
BEGIN LOOP dbms_output.put_line(utl_tcp.get_line(c, TRUE));  -- read result
WHEN utl_tcp.end_of_input THEN NULL; -- end of input
Could someone help me on next steps on How to open and read the .csv file present in SFTP/FTP server and load it into Oracle DB table ?
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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 "";
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 "";
option domain-name-servers 10.x.x.x,;
option domain-search "", "", "someothername";
option host-name  = binary-to-ascii (16, 8, "-", substring (hardware, 1, 6));

zone {
 primary 10.x.x.x;
 # uses name format could use IP address format
# zone {
#  primary serverhostname;
# }

include "/etc/dhcp/groups.d/list.conf";
include "/etc/dhcp/subnets.d/list.conf";
include "/etc/dhcp/hosts.d/list.conf";
~     …
We have a TCP/IP interface between a Millennium SPA POS system and Oracle Opera PMS system at our Hotel. There are a total of 8 interfaces and 7 of them have no issues. This specific one keeps disconnecting on the POS side. I have a packet capture that shows all traffic over the specified port and it looks like every 15 minutes exactly the interface disconnects.  On the POS side, we get an error message a pop up that must be clicked. Once you click ok on the pop up, the systems immediately automatically reconnect with out issue. As far as i can tell there is zero traffic unless someone is actually sending a transaction across. There is absolutely no keep alive being sent as far as i can tell.

I have attached a packet capture here.

I have not dealt with these serial/ip interfaces very often and dont really know what i am looking for in the packet capture. But it does look like the PMS system is sending a RST packet which from what i am reading terminates the connection.  Can anyone confirm this is what is going on based on the attached packet capture? I appreciate any assistance here. We have been battling this for 2 weeks now and both sides vendors are telling us it is the other sides problem.

Cloud based application having issues with ldaps bind to our Domain Controller in DMZ.
The application vendor is seeing the follwoing log entries on their side:
           [7:Public User][1024:application notice][R] (:) - Unable to bind to the LDAP server.

Based on this they have taken a wireshark capture and seen the following sequence of packets:-
Source -> destination (DC)   TCP    49662->636 [ACK] Seq=805 Ack=12910
Source -> destination (DC)   TLSv1  Application data
Source -> destination (DC)   TLSv1  Encrypted Alert
Source -> destination (DC)   TCP    49662->636 [FIN, ACK] Seq=927 Ack=12910
destination (DC) -> Source   TCP    636->49662 [ACK] Seq=12910 Ack=928
destination (DC) -> Source   TCP    636->49662 [RST,ACK] Seq=12910 Ack=928

They are saying that the reason packet analyser highlights the [RST, ACT] packets in red is because after the connection closure by Cloud Application server (source) [FIN, ACK] , server is expecting a final [FIN, ACK] from Domain Controller  (destination) but [RST, ACK] arrives instead. And thus they believe that it could be a issue with the Domain Controller.

Is this claim correct?
What can we do to troubleshoot this further?
Windows 10 Pro machine with a USB 4G card changes the TCP/IP v4 settings to a blank IP address when connecting to the mobile network. If I change this back to dhcp as soon as I connect again it reverts back. This is the second machine I have had this problem on and cannot find a solution.
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?
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 The 169.x.x.x has been removed and the has been changed to

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 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' failed on the following DNS server:  

DNS server IP address:
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.  

Determine what might have caused this failure, …
Need to know about vpn services,vpn name and there related circuit id function?
Ethernet and T1 service-
How they are related to CLLI?
Is there any link between switch and service wire center CLLI?
What are LATA? How it used in modern communication?
I have a kernel module, in which :

It changes the saddr field of outgoing packets and fixes it back(daddr) in incomming packets ...
I'm calculating new checksum for ip and tcp headers ...
So in client side I change ip - server side receives it(SYN packet) and sends (SYN-ACK) packet - but client side - sends (Reset) packets and trying again to process tcp handshake ...

I've seen to another kernel-module examples - dnat/snat - my code is analogical ? My be ebtables make my hooks to work incorrect ?

Interfaces: eth0 - XXX.XXX.XXX.1 eth0:0(alias) - XXX.XXX.XXX.2
Client (original ip XX.XX.XX.1(eth0) and XX.XX.XX.2(eth0:0))
                                                               SERVER (ip YY.YY.YY.YY)

     USER-SPACE app creates tcp-socket and connects to (YY.YY.YY.YY)

     TCP (SYN) -----------(packet ip XX.XX.XX.1-YY.YY.YY.YY[ip.sum1, tcp.sum1] )----->
     NF_INET_POST_ROUTING ( ip XX.XX.XX.2-YY.YY.YY.YY[ip.sum2, tcp.sum2] )

     <-------TCP (SYN ACK) ------(packet ip YY.YY.YY.YY-XX.XX.XX.2[ip.sum1, tcp.sum1])
     NF_INET_PRE_ROUTING ( ip YY.YY.YY.YY-XX.XX.XX.1[ip.sum2, tcp.sum2] )


     TCP (RST) - against TCP (ACK) - that is the question ....

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I have two questions about "under the hood" processes executed by Webrequest and the getresponse method.

1) I have noticed while packet capturing that, when doing a webrequest with a payload, packets starting a TCP/IP connection are sent and received *before* the getresponse method?  I would have expected the payload to be cached and sent only when the getresponse was called?

2) I have a webrequest case that has me puzzled.  It is an HTTPS URI.  All proceeds as expected (443 TCP/IP connection made before getresponse called) until the getresponse is called.  When that happens, the process attempts to create a new TCP/IP connection to the server, this one being on port 80 (not HTTPS).  Since the request is not HTTPS, the server ignores it and the process times out with a "no response from server".

What would cause the getresponse method to spawn a new connection, and why would it send it via HTTP when the original connection was made via HTTPS?  The certificate for the server is valid, and I have tried turning off the check-certificate functionality.

Thanks for any insight on both questions.

Bryan Hunt
Need to access an application on a company Windows Server from outside using an iPad, Server has a private Static IP (10.x.x.x). The office router has Public Static IP interface. How can I access the server from outside on an iPad? Can I access the server using a public IP is this situation? Please advise.
I have a Juniper QFX. My infosec team wants me to disable the TCP timestamp as per the ID: 80091

Now I know how to disable ICMP timestamps, but not the TCP timestamps. And I don't want to disable it for the whole QFX. If it can be done for an interface, that will be awesome.

Any help will be appreciated.
Hello , does anyone knwo how to transfer iPhone contacts and messages to Android phone without any loss ? i've tried many ways to transfer them , but always fail ,and i don't how to connect the differen operation phones ,
Hi Networking Gurus,
Sorry if i sound stupid but i am very new to networking.My application work as ESME  for the smsc  and it seems that recently we observing huge delay in ack of submitted  message or ack not coming at all.I can see in netstat output of linux send queue is increasing hugely.Taken a tcpdump in which i can  see to much [TCP Dup ACK],[TCP Out-Of-Order],[TCP Retransmission]

Also i see in wireshark
Smsc send mesg with seq:1 ACK:1 Len: 51 -->" -> SMPP SMPP Deliver_sm"
but we reply by -> TCP 42758 > dynamid [ACK] Seq=4141 Ack=52 Win=128 Len=0
That means are we losing frames.Pls help
How to enable Mysql server access through TCP/IP
where mysql installed in Centos machine.,.I am trying to access using mysql workbench it through TCP/IP but throwing error .. attached screenshot.
Where as when I select TCP/IP over SSH .. I can able to connect .
I'm receiving this error among others, listed after. I have no idea why this error is coming up! how do I address?

Event 4879 MSDTC Client 2
MSDTC encountered an error (HR=0x80000171) while attempting to establish a secure connection with system SERVERNAME.

More errors that I don't understand and one that Microsoft doesn't even seem to know about (starting with that one)

The error that MS has no info on in Event ID Online help
Event 4230 TCP/IP has chosen to restrict the congestion window for several connections due to a network condition.  This could be related to a problem in the TCP global or supplemental configuration and will cause degraded throughput.
Need to refresh DHCP IP address reassign Needed to command
I have an IPv6 box that is supposed to be routing via HE. I have radvd configured, so it hands out a /64 subnet as follows:

interface enp2s0
      AdvSendAdvert on;
      AdvManagedFlag off;
      AdvOtherConfigFlag off;
      prefix 2001:470:1f17:204::/64 {
            AdvOnLink on;
            AdvAutonomous on;
      # This is the DNS server on the internal interface
      RDNSS 2001:470:1f17:204:feaa:14ff:fe53:2eec {
      route ::/0 {

I have the interfaces up as follows: enp1s0 (enternal interface), enp2s0 (internal interface to LAN) and hurricane-ipv6 (interface to HE):

enp1s0: flags=4163<UP,BROADCAST,RUNNING,MULTICAST>  mtu 1500
        inet  netmask  broadcast
        inet6 fe80::219:5bff:fe2f:e30  prefixlen 64  scopeid 0x20<link>
        inet6 2001:470:1f16:204::2  prefixlen 64  scopeid 0x0<global> ...

enp2s0: flags=4163<UP,BROADCAST,RUNNING,MULTICAST>  mtu 1500
        inet  netmask  broadcast
        inet6 2001:470:1f17:204:21f:c6ff:fe5e:58b1  prefixlen 64  scopeid 0x0<global>
        inet6 fe80::21f:c6ff:fe5e:58b1  prefixlen 64  scopeid 0x20<link> ...

hurricane-ipv6: flags=209<UP,POINTOPOINT,RUNNING,NOARP>  mtu 1480
        inet6 fe80::b847:c15a  prefixlen 64  scopeid 0x20<link>
        inet6 2001:470:1f16:204::2  prefixlen 64  scopeid 0x0<global>...

lo: flags=73<UP,LOOPBACK,RUNNING>  mtu 65536
        inet  netmask
        inet6 ::1  prefixlen 128  …
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how to send and receive the message through in tcp/ip using servlet

I have an interesting setup. We switched to a hosted voip solution but for our emergency analogue lines we purchased two fxs vega 3050g gateways.

I have successfully configured the dialplans between the two units without the freepbx box as an in between. It is such a simple setup to just have it dial our security desk the pbx was not needed.

We are getting ready to deploy but have two lingering issues. To route calls between interfaces and the two gateway devices you have to initiate the sip handler to apply codecs and handle advanced features like call waiting. So dialing by IP between devices or loopback on between interfaces.

The one limitation I am running into is only one call at a time will take place between gateway... almost like the port is busy or it can only route one call at a time between gateways. Similar issue happens when trying to use call waiting... the first call connects but when I initiate the second call I get one indicator tone then the call fails with a cause code 41 (temporary network error)

Is this a matter of me needing to use more than the default udp port 5060 or am I just missing something here? I'm not a phone guy so I have a slight learning deficit.

I have combed through sangomas support site and manuals and found nothing like this... their support has yet to offer any solutions (on almost any of the setup.. which is troubling) so I'm turning to the community.

Thank you in advance
(1) how can i know subnet mask & default gateway of any ipv4?
(2)Explain  dns server in detail?
devices behind a switch are not able to acquire DHCP. when i assign a static IP it works OK.  the switch is connected by fiber optic to a core switch where the DHCP is configured
we have a TZ-210 wireless that need to change a couple of things on.  

We are connected to a comcast business gateway device.  It has wireless and we use that as an outside wireless,  It is not setup to access the internal network.  When we setup a laptop of phone we use that for VPN testing and remote connectivity.  I have 2 issues.

1. I cannot connect to the management interface on the modem, it is the default  It keeps getting dropped in the firewall.  What rukes do I add to tallow this?
2. We cannot send email from our mobile devices when connected to the Comcast wireless.  I would expect it to be a rule as well, but I'm not sure what to add to make this work.

We want to keep the comcast wireless off the internal network. But we need to access the management interface, plus some of the users need to be able to send via exchange when using devices or phones and sending exchange email.

I have 5 IP's assigned by AT&T to me on my On Demand Fiber circuit, but I only have 1 public address to the WAN. How do configure my 3 TZ300 to each use one of the assigned IP address and each to be a DHCP server?






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.