Questions tagged [network-protocols]

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Spanning Tree Protocol: How are ports selected to be designated or non-designated?

I have read a lot about STP now. Perhaps not enough yet, but it starts to get difficult to get details. I have understood the mechanism how all bridges select their root port. After having exchanged ...
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can http clients configure if they want persistent or non-persistent connections with the http server?

I want to understand, if depending on how client configures the http connection, the server can behave in non-persistent manner or persistent manner, so in effect some clients can connect in ...
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Does http protocol standard support long polling?

I recently read about long-polling concept which can be used with http. I want to understand, if any http protocol standard itself supports long-polling concept, so that depending on how client ...
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What is the name for protocol 1521 (Oracle)

What is the name for the Oracle protocol used by the port 1521? Like TDS (Tabular Data Stream ) 1433 for Microsoft SQL Server.
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DigitalOcean: Custom network ports not opening on Debian droplets

I have hosted multiple web servers on port tcp/80, tcp/443, tcp/3333, tcp/8443, tcp/8080, tcp/8081. The VM is a DigitalOcean droplet with Debian 10 OS. I able to access web servers at port 80 and 443 ...
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SMTP "root+:"|sleep 5 #"" what is meant by this query i found it in dataset of smtp protocol

what is "root+:"|sleep 5 #" in SMTP, I have found this line in dataset of SMTP protocol I have attached a picture of dataset, any one who can help me by explaining whats happening in it....
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Reliable transfer protocol designed for a known static bottleneck size and high packet loss?

AFAIK, most reliable transfer protocols like TCP tends to use some method (like packet loss) to detect the size of the bottleneck. In my use case, however, the bottleneck bandwidth is a known value of ...
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IPv6 Protocol failure

I am having a weird issue with IPv6 in my Windows Server 2019 Domain Controller. I was trying to configure IPv6 for the domain, I've typed some commands as below, when I restarted the server it doesn'...
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How can I isolate a single TCP connection on Wireshark?

I just started using Wireshark for network troubleshooting purposes and I am a little confused about one thing. I requested a webpage and for the next 10s I monitored the data. I then used the filter ...
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3 answers
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DNS and OSI Layer Working

I would like to clarify a doubt that's haunting me after learning DNS. I'll briefly write it as a question. "A user was watching a video in youtube and suddenly the DNS server which was used by ...
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Is the Matrix protocol Fediverse?

The title says it all. Reading about the Fediverse, the Matrix protocol seems to fit its characteristics, however I found no reference of that anywhere.
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Rekeying denies protocols/NAT issue or config?

I'm using strongswan to connect to a MAC server using IKEv2/IPsec configuration. The server uses the proposed algorithms to establish the SA and everything works great. Upon rekeying however, the ...
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Do ports change for every request? Are Ip ports are different from system ports?

A typical ip address has >65k ports then again a system that runs localhost offline has port which sometimes face conflicts. Am very under-read in this area please give some light. Pardon my English. ...
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UDP is received, but TCP is not

I have two types of software connected to the internet - both HAVE to be continuously connected. One connects via UDP protocol and I have no dropouts. The other maintains its connection through a TCP ...
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DNS server - respond to client with "go resolve from that DNS server"

I'm trying to figure out how to build a DNS response that refers the requesting client to try resolve from a different DNS server. For example, Client PC makes a request to resolve A record "google....
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Is AS2 versions backwards compatible?

Is AS2 version 1.2 compatible with version 1.1? If I'm sending messages from system using version 1.2 to a system that only supports version 1.1 will the message get delivered ok? Messages would be ...
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What exactly happens when a TCP segment is sent to a broadcast address?

Does the segment get delivered -- and the recipients are supposed to drop it? Does the segment get dropped at the (layer 3) switch/router? Or something completely different? Explanations or "RTFM!" ...
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Why does LAN stops working if switch is connected to two upfeeds?is [closed]

If I connect my switch to two upstream feeds from my ISP, my internal LAN stops functioning (see illustration below). What is it in the TCP/IP protocol that is disrupted to cause the above? ...
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Prevent Unjoined-to-domain computers from connecting to my network

How to prevent any computer that is not joined to the domain from requesting any service from my network? Considering that the computer is on another network.
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Security issues with SMTP

I am looking at SMTP and POP3 and am trying to find the security issues with both protocols, I have found that SMTP can be easily impersonated on port 25. However I am struggling to find security ...
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How does VXLAN prevent duplicate MAC addresses?

It seems to me that VXLAN network identifier(VNI) works silimar to a prefix keeping identical MAC addresses on different VXLAN segments separate, so that they can coexist without duplication issues. ...
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What application is connecting to a remote site?

I can see with Wireshark that every 5 minutes I have a connection from my computer to ip 165.254.162.243 on udp/8253. This has been going for months. I cannot identify what application or process is ...
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What's URD in iptables?

I've been playing around with various iptables configurations lately, and I noticed that adding a rule which involves --dport 465 (usually reserved for smtps) results in the human-readable dpt:urd ...
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raw sockets, iptables and the fact that

iptables -P INPUT DROP iptables -P FORWARD DROP iptables -P OUTPUT DROP So, I just found out that these cute rules don't do s**t when it comes to raw sockets. I know that grabbing a raw socket ...
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Installing Unsigned Network Protocol Driver Windows 2012R2

I'm trying to install an unsigned Network protocol driver on a 2012 R2 Windows server installation however the installation just fails the same way unsigned device driver fails. I've already unlock ...
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Simultaneous http requests planning

A development Meteor app runs in a docker container on aws cloud, it accepts user input and makes HTTP requests to 3rd party websites, parses the data and sends back to the user. Apology; my limited ...
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Huawei Secospace USG 2000 on a non Default Port

I would like to know which is the default port of IPSec. I have tried to connect on all default ports, but I was unsuccessful. Also, I have applied NMap to them, but have no response.
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How to capture network packets that use SS7 protocol using Wireshark?

Since SS7 protocol stack is used in GSM mobile telephony network, we can't get the packets of SS7 protocols using Wireshark in Windows Computer and browsing in a web browser like Google chrome. So ...
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Does anything changes for a client in the API communication after the command STARTTLS is sent and a response received

I'm trying to understand how the command STARTTLS in IMAP works exactly and what becomes different when it's sent. After I've sent the command "STARTTLS" before login process and received the response ...
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can tcpdump detect higher level protocols like wireshark?

Wireshark will guess what higher level protocols are being used in a packet, but how can I get tcpdump to do likewise (or any other linux command line tool)? For example, the following screenshot ...
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Enforce a client hardware address via DHCPv4

Is there a DHCPv4 option that allows a client to tell the server never or at least for some time to deny any other client hardware address than its own? I'm looking for a way to deny any other host ...
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2 votes
1 answer
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What's the legit use of a deauthentication packet?

Most people that have tampered with external wireless networks in a malicious fashion for the sake of education (hopefully your own personal testing network) have probably heard of a deauthentication ...
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Nic teaming server 2012 r2

I've been asked to build a server and team the nics, my understanding is the nics should each be dhcp enabled and the team should be configured with a static ip. Would this be correct and also what ...
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SNMP/PJL - used area printed on a page

How can find the effective area printed on a page direct from printer device? I can't access the file stream to do direct on it.
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How SMTP (receiving emails) works?

I have a very hard time to understand how SMTP works. I've read already: Message Submission for Mail Internet Mail Architecture Internet Message Format Simple Mail Transfer Protocol I know the SMTP ...
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2 votes
1 answer
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Why is the DHCP lease start time greater than the end time

On our DHCP server I see this quite a bit on some of our leases and I am not sure why its being reported like this. lease <IP Address> { starts 5 2015/08/21 13:22:20; ends 5 2015/08/21 13:22:...
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MAC Layer Retransmissions during the same TXOP

Back in the day I was messing around with MadWifi and, if I remember properly, after a packet was transmitted if the sender did not receive an ACK in SIFS time after the completion of the transmission,...
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Under what circumstances is TCP-over-TCP performing significantly worse than TCP alone (2014)?

Many admins keep perpetuating - on ServerFault and elsewhere - how bad of an idea TCP-over-TCP is, e.g. in VPNs. That even the slightest packet loss will make one suffer from at least severe ...
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Worldwide IP Latency [closed]

I want to create a simulation of the protocol MIPv6 (http://www.ietf.org/rfc/rfc3775.txt), for this reason I need information about latency, jitter and round-trip time. My first guess is install ...
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-2 votes
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Configure Protocols using iptables log file with ndpi [closed]

I am using iptables with ndpi to filter my network and add two rules to my iptables rules they are iptables -I INPUT -m ndpi --http -j LOG iptables -I INPUT -m ndpi --google -j LOG In my log file I ...
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What is the KRYPTOLAN protocol?

I've searched for a while and can't seem to find any information on what KRYPTOLAN is. For the transport layer, IP protocol number 0x41 is assigned. In addition, ports 398/udp and 398/tcp are also ...
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Token Ring Number of nodes in MAU [closed]

why the token ring has limitation of 260 nodes per MAU using STP cables? How the number of nodes per MAU is calculated? I know we can use more than 260, but why IEEE-802.5 is Standardized it to 260 ...
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6 votes
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Tools for detecting network traffic filtering [closed]

In Iran we have an ongoing problem with the govt. blocking and manipulating various network protocols. I'm looking for a tool, framework or platform to help us analyze and report on any of these ...
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Routing table taking long time to update for adhoc networks and OLSR

I am using OLSR to implement adhoc network and analyse the throughput.I have olsr working on 3 interconnected computers on adhoc network. I am using jperf to simulate and visualise the data ...
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ow to get protocol signatures?

Does anyone know how can we get signatures for various protocols e.g. BGP, DHCP, VxLAN etc? By signatures, I actually mean the pattern (e.g. something like 0x234557888) used for pattern-matching in a ...
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2 votes
3 answers
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Can i set 443 as default web port which means it can only be accessed via https and no port 80

As title says, I want to set my apache to listen on 443, and will configure SSL. So, My Question is :- 1). Does that mean, i will not have port 80 or any other port which is no ssl ? 2). My site ...
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Source and Destination Packets on Wireshark Relative or Absolute?

New in Packet Analysis. Sniffing on the Ethernet device of my computer. Does the Source and Destination columns on Wireshark tell the source and destination from where the packet was originated and ...
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How can i go ahead to configure two subnetted networks to apache so as to create two lone networks that are connected via switch?

I want to connect 15 systems to a server so that they do not communicate among themselves directly but do so via server, how should i go ahead? i need to allot say 5 systesm to HR people and 5 other ...
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Why does ipv6 not specify a protocol version?

I am relatively new to dealing with network packets, but as I look into the ipv6 header formats, I do not see a place where the ipv6 headers define what protocol is used in the data section -- but the ...
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12 votes
2 answers
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Why is ICMP categorized as a layer 3 protocol? [closed]

ICMP is categorized as a layer 3 protocol in the OSI model, but as far as i can tell it does not meet the definition of a network layer protocol. It does not provide addressing or packet routing (it ...
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