UDP stands for User Datagram Protocol. With UDP applications can send messages (datagrams) to other hosts on a network without requiring prior communications to set up special transmission channels or data paths.

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how i can identify which process is making UDP traffic on linux?

my machine is continously making udp dns traffic request. what i need to know is the PID of the process generating this traffic. The normal way in TCP connection is to use netstat/lsof and get the ...
3
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1answer
769 views

How to add a broadcast address to loopback with ifconfig on a OS/X?

I am trying to use ifconfig to turn on broadcast on my loopback interface. It currently reads: lo0: flags=8049<UP,LOOPBACK,RUNNING,MULTICAST> mtu 16384 As you can see, no broadcast address! ...
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11answers
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What is the difference between UDP and TCP?

My router has two protocols (and a "both" option) that I can select when setting up port forwarding: UDP and TCP. What is the difference between these two protocols and when would you select one over ...
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3answers
883 views

Why is it 3-way-handshake and not more?

TCP uses the 3-way-handshake mechanism. I understand how it works pretty well but I wonder why it's not 4, or even 5-way? Is it because that's too much overhead and is not needed?
0
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1answer
692 views

how to enable port 7777

I am initiating file transfer using tcp on openfire server. But I am not able to open the port number 7777, from which I need to send files. I changed the security setting in the admin console panel ...
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2answers
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What is the “in-the-wire” size of a ethernet frame? 1518 or 1542?

According to the table here, it says that MTU = 1500 bytes and that the payload part is 1500 - 42 bytes or 1458 bytes (<- this is actually wrong!). Now on top of that you have to add IPv4 and UDP ...
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5answers
2k views

Can TCP and UDP packets be split into pieces?

Can TCP packets arrive to receiver by pieces? For example, if I send 20 bytes using TCP protocol, can I be 100% sure that I will receive exactly 20 bytes at once, not 10 bytes then another 10 bytes ...
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2answers
2k views

Can I test broadcast packets on a single machine?

I want to have a server sending broadcast UDP packets and two other clients, in the same machine, receiving them. Can I do that somehow? What IP address would I use? @gravyface gave me hope but I ...
3
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1answer
954 views

tcpdump udp data capture latency

I am using tcpdump to capture UDP packets and analyze network latency between a UDP broadcaster and my server. To calculate latency I compare the source host timestamps reported in UDP application ...
2
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2answers
2k views

Reduce firewall rules by half - one iptables rule for tcp and udp

I have a number of iptables rules on my firewall that look like this: iptables -A zone_lan_forward -p tcp -d 1.2.3.0/24 -j ACCEPT iptables -A zone_lan_forward -p udp -d 1.2.3.0/24 -j ACCEPT Is ...
2
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2answers
358 views

Multicast IP Addresses

I posted this on StackOverflow and was told it might be more appropriate here. I'm having trouble understanding how multicast addresses work. First off, is it true that if I have N clients or peers ...
0
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1answer
930 views

How to relax firewall for UDP connections/ports for a specific IP address?

My server is Red Hat Enterprise Linux Server release 5. iptables version is v1.3.5. I want to allow all UDP connections / port for the IP address 192.168.0.200. This IP address is configured in my ...
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2answers
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Iptables: “-p udp --state ESTABLISHED”

let's look at these two iptables rules which are often used to allow outgoing DNS: iptables -A OUTPUT -p udp --sport 1024:65535 --dport 53 -m state --state NEW,ESTABLISHED -j ACCEPT iptables -A ...
4
votes
2answers
6k views

Should I use TCP or UDP to run a web server

I have just installed Apache web server on my computer. I have managed to use it locally (I can open index.php from my computer using my web browser). But I would like to make my web site available ...
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4answers
2k views

How does UDP track connections?

If UDP does not establish a connection as TCP does.. it seems the only way it could track connections is source ip/port and destination ip/port. Is this correct? So, I guess there are special packets ...
0
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1answer
79 views

How can I determine if my VPN is passing through UDP traffic?

I have an client application that is unable to connect with it's server counterpart over a VPN connection. Server is Windows SBS 2011, client is Windows 7 64bit Enterprise. Using Windows VPN client. ...