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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Why would a university block incoming UDP traffic with destination port 53?

From my understanding DNS uses UDP and port 53. What undesirable things could happen if incoming UDP packets to port number 53 weren't blocked? UPDATE: Packets originate or are destined to the ...
2
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0answers
38 views

How to use an IPv6 Edge router in an IPv4 network?

Background I have the following set-up: I use 6LOWPAN (IPv6 implementation in IEEE 802.15.4) on my sensor link that have IPv6 addresses (stateless) as aaaa::xx/64 It uses RaspberryPi (RPI) as an ...
0
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1answer
16 views

udp broadcast on port 25860

I used wireshark on my local network (to test it), and i noticed that there is a lot of udp packets send one broadcast, and the majority is coming from only one host. Theses udp packets are send on ...
0
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0answers
17 views

How to make svlogd send logs via UDP

I am currently using runit + svlogd for supervising some applications, but when deploying to multiple machines, I have the need to centralize/unify the logs in a single place in order to simplify ...
0
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0answers
10 views

UDP destination address during port forwarding?

I have setup a connection using Qt in the LAN, PC1(192.168.1.195) will send UDP packets to PC2(192.168.1.201) with no problem. But now, PC1 and PC2 are now working under different routers. So now PC1 ...
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1answer
80 views

What are the ports needed for L2TP VPN on Mac OS X Server 5.0.15?

I'm configuring a Mac as a server with a VPN service. So, I opened the ports listed as used by VPN in Apple documentation: UDP 500 -> 500 (+ESP and AH) UDP 4500 -> 4500 Any UDP -> 1701 (I got to ...
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0answers
11 views

CentOS Drupal Site/Domain Sending UDP Attacks on Different IPs [duplicate]

My Drupal 7 site is hosted on a Cent-OS 6.5 VM. The hosting service provider notified me about an malicious activity on site and site is sending UDP packets on different IPs. Following is data ...
5
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2answers
128 views

How to allow UDP broadcast between interfaces on a Cisco ASA 5506-X

I have a CISCO ASA 5506-X with 4 configured interfaces and a set of access-lists etc. It is configured via CLI and is running in routed mode, not transparent. Everything is running well, but now I ...
1
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1answer
38 views

Can't connect to python server on LAN

So I have this python server which just returns the uppercase sentence which came as a input: from socket import * serverPort = 12000 serverSocket = socket(AF_INET, SOCK_DGRAM) ...
0
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0answers
15 views

Packets not being delivered to application

First of all sorry if this is not the right place. So... I have a problem. I'm working on a linux board (the distro is created with yocto, kernel is 3.10.17). I have several network interfaces (WWAN1 ...
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0answers
29 views

netcat UDP port test response issue

I am running a game server on a Windows Server 2008 VPS/VDS through port 12203. I want to be able to automatically restart the game server exe file if it crashes. So, my strategy is to use netcat to ...
0
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1answer
31 views

Why are duplicated UDP packets being dropped 10 out of 11 times by this iptables configuration?

I am trying to duplicate UDP packets flowing to port 50007 on an Internet address from devices on a local NAT network (192.168.12.0/24) with the intent of processing them locally (on ...
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2answers
63 views

How to connect a client behind a NAT router to an Asterisk server behind a NAT router?

I have an asterisk setup on a server. The local IP address is 172.22.9.200 and extenal IP address is 75.45.185.100. My client device is an android phone that is connected to a router and it which ...
4
votes
1answer
110 views

udp packet delays in my dedicated WIFI network - can i force UDP nodelay over wifi?

I have a dedicated app and network development for passing UDP packets over a wireless network. The totality of the network is a PC (Mac OSX or Linux) which sends the packet-->router/AP-->WIFI ...
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2answers
50 views

Does UDP includes of source address?

Both UDP and TCP does not include source address, but how does it say UDP IP spoofing is easier than TCP? For example, the following webpage also says about UDP vulnerability. "Unlike TCP, UDP does ...
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1answer
31 views

What does the following UDP connection mean? [closed]

What does the following entry mean? Is that mean someone has connected to the server from this IP or somthing else? Nov 23 15:33:54 www-prod-2 snmpd[1573]: Connection from UDP: ...
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0answers
35 views

TCP and UDP ports usually blocked [closed]

Which are TCP and UDP ports most likely to be blocked? I refer especially to the client edge of the network. To start I guess SMTP (25), SIP (5060) for TCP, Traceroute (33434) for UDP.
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0answers
59 views

UDP Port Forwarding Error: channel 2: open failed: connect failed: Connection refused

My situation is as follows: I have currently trying to have a program between two Hosts send UDP packets over a SSH Tunnel. There is also a host intermediate between the two hosts. Note Server01 ...
0
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1answer
16 views

Does STUN work on majority of NATs?

I've been largely ignoring STUN protocol as noise for a while, but I keep encountering it here and there, and I'm wondering of it's general usability. If I understand it right, STUN is only useful if ...
1
vote
1answer
37 views

iptables accept specific packet id

I want to allow only packets with a specific id (identification field), for example packets with id=3 are accepted and others dropped. And I want to do the same thing with the offset, so for example ...
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2answers
80 views

Any protocol used by TRACEROUTE ? ICMP or UDP [closed]

Any protocol used by TRACEROUTE : ICMP or UDP or IP ? Or use them all : Encapsulation ?
2
votes
1answer
80 views

difference between local port range & UDP sending port using dig on Debian nameserver resolver

When i go to my local port range on Debian 7, i can see that my ephemeral port range is: cat /proc/sys/net/ipv4/ip_local_port_range 32768 61000 My /etc/sysctl.conf is empty. Normally that would ...
0
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0answers
68 views

How to prevent outgoing UDP flood

I've been googling for hours now but can't find a sure or helpful answer. I need to disable high-volume outgoing UDP from my server. I'm trying to configure APF because of the RAB functionality, but ...
7
votes
2answers
238 views

Windows Server 2012 - RDP over UDP not working

I have a Windows Server 2012 (not R2) machine, hosted within Hyper-V virtualization with RD Session Host & RD Gateway installed. It is used to run a desktop GIS application. The performance over ...
0
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0answers
34 views

Colasoft Packet Player with Loopback-Adapter - Cannot recieve UDP-Packages

I have some problems with Colasoft Packet Player. I am trying to send the UDP-Packages over a Loopback-Adapter (Windows 7, I want to send and receive them over the same computer) and to read them with ...
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0answers
128 views

UDP packets seen on interface level but not delivered to application on RedHat

I have a problem with receiving UDP traffic on a RHEL6 server. When capturing the traffic with tcpdump, the packets are visible (checksums are correct, the destination IP and MAC match the machine's ...
0
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2answers
42 views

SMB / CIFS / Samba Connectionless or Not whilst transfering files?

I have been researching this for a bit, but I have been getting conflicting answers, does samba, from my gatherings, SMB runs on ports TCP & UDP 137-139 & 445. But I have no idea therefore ...
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1answer
352 views

Firewall UDP Flood Dos/DDoS

Recently I have been suffering from what appears to be a UDP query flood attack. I am looking for a way to block the attack using a software firewall such as iptables, this should be possible, as ...
2
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1answer
53 views

I need to REJECT first incoming UDP packet by srcip

Im currently under attack by spoofed udp packets. Every spoofed ip trying to send just 1 udp packet in 30sec. But there is tons of ip. I need to drop first packet. But if same srcip in 30sec sends ...
0
votes
1answer
120 views

Blocking ddos string with iptables [duplicate]

I want to ask how do block spefic packet payload? 14:46:35.837759 IP 145.92.16.14.27017 > x.27030: UDP, length 25 0x0000: 4500 0035 44a4 0000 ee11 53ae 915c 100e E..5D.....S..\.. ...
1
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1answer
42 views

Dest host dont accept UDP when there is no route to source

I have three hosts with following config: Host A: IP:192.168.1.1/24 Host B: IP:192.168.1.2/24 Host C: IP:192.168.3.1/24 Everything happens on CentOS 6, and all interfaces are VLAN tagged (if it ...
0
votes
1answer
157 views

How to kill a UDP connection from a process Windows Server 2003

I have a program running and it connects to a UDP port to perform multi-casting. I'm trying to simulate a network failure where that process cannot reach the UDP endpoint but everything else still ...
0
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0answers
445 views

Enable UDP protocol in Remote Desktop Connection

I have a computer to which I am connecting via RDP. However, using the default Windows applications (Remote Desktop Connection) probably will not use UDP port. By clicking the connection information ...
0
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1answer
131 views

Sending file with netcat over UDP: Unusual Wireshark output

For the purposes of demonstrating differences between TCP and UDP, I'm piping the contents of a file across a network connection, and recording the interaction with Wireshark. Everything looks normal ...
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1answer
92 views

How to tunnel UDP traffic with pptpd VPN?

I've set up a VPN on a Debian (7.8) server. On a Windows 8 machine, I can set up a VPN connection to the server and it works fine for TCP applications. Everything is going through the VPN. However, ...
0
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0answers
12 views

Route only on output chain?

I have two machines A and B. I want to send iperf traffic from A to B, but first have it route through a userspace program on A. I did this with a tunneling device: therefore, I used the command ip ...
0
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0answers
71 views

SYN/ACK not received by iperf client?

I have an application that essentially consists of four components A, B, C, D. A and B are on the same machine - B and C are separate machines. Traffic is generated by an iperf client on A with a ...
1
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1answer
102 views

iptable rule and iftop command

Someone is flooding our server with UDP packets. I simply put iptable rule to block that IP. However, when I run iftop command I can see a huge traffic coming to my server. When i looked for iptables ...
0
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0answers
64 views

rsyslog tcp packets containing multiple log messages

I have rsyslog receiving logs over udp and then relaying them over tcp to a load balance (nginx) which passes them along to SIEM collectors. The setup looks like this: network devices/appliances ...
1
vote
1answer
508 views

socat udp packet forwarding with source address

I am trying to use socat (instead of iptables) for UDP port forwarding. I just need to redirect some traffic from UDP port 162 to 33162. I am using something like this: socat ...
1
vote
2answers
156 views

Can't change source IP address (to floating ip) for udp outgoing packages

I'm having trouble getting a cluster to work using pacemaker and corosync. Here is my hardware configuration: Network: 192.168.3.0/255.255.255.0 Gateway: 192.168.3.1 node1 (Ubuntu Server 12.04 x64) ...
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0answers
20 views

Can't stop the UDP packets [duplicate]

My datacenter has stopped my cloud server because my server is producing excessive UDP traffic. I have run: tcpdump -i eth0 udp and following is a sample set of log. 13:09:42.789583 IP ...
0
votes
1answer
75 views

Caching UDP packets with iptables

I have a server set up to forward all of its packets on a certain port to another host with the following command; iptables -t nat -A PREROUTING -p udp --dport PORT -j DNAT --to-destination IP:PORT ...
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votes
1answer
136 views

heartbeat timeout error in tsunami deamon

I am trying to transfer a large file from server A to server B using tsunami. I am getting following error: Heartbeat timeout of 15 seconds reached, terminating transfer. And here are details: ...
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0answers
80 views

Something like Receive Segment Coalescing for UDP

The TechNet page on RSC states: RSC is defined only for TCP connections. RSC does not work with User Datagram Protocol (UDP) and other transport layer protocols. This is of course ...
16
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1answer
270 views

Vendor whitepaper says: 5Mpps no prob. I'm already hitting a wall at 120kpps. Where's the bottleneck?

HP's whitepaper on their QLogic (fka Broadcom) NetXtreme II adapters, which includes the specific NIC that I'm testing, states (page 7) that their small packet performance for packets up to 256 ...
0
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1answer
47 views

How does acting as an RDP host affect UDP visibility/routing?

This is an odd one. First, THIS IS NOT A NETWORKING ISSUE. This is an "rdp host behavior" that can be seen, from one persective, via the behavior of an RDP app. (see What happens to a Windows 7 ...
0
votes
1answer
615 views

Block an IP for UDP

I am under UDP flood attack. I used following protections to solve it: iptable IP ban: iptables -I INPUT -s 37.187.231.xxx -j DROP Tried another iptable syntax /sbin/iptables -I INPUT -i eth0 -s ...
8
votes
2answers
3k views

Extreme UDP packet loss at 300Mbit (14%), but TCP > 800Mbit w/o retransmits

I have a linux box I use as the iperf3 client, testing 2 identically equipped Windows 2012 R2 server boxes with Broadcom BCM5721, 1Gb adapters (2 ports, but only 1 used for the test). All machines are ...
0
votes
1answer
246 views

Make Asterisk to serve another subnet

I have server with Linux Ubuntu 12.04. It has two subnets - 192.168.0.1(eth0) and 192.168.1.1 (eth1). There is an Asterisk server (IP PBX) connected to first subnet, lets say it has IP address ...