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.
2
votes
2answers
61 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
votes
0answers
29 views
How to force use of tcp instead of udp for rpcbind?
I'm trying to use tcp/111 for rpcbind under Debian Wheezy instead of udp/111. The portmap in Squeeze uses tcp/111 without any special configuration, but Wheezy fails.
Even numerous sites (as well as ...
1
vote
2answers
44 views
TCP vs UDP Error-Checking
I've bounced upon two articles that describe in-depth on how TCP and UDP connections work. However there is some kind of inconsistency. Where one article tells me that UDP does no Error-Checking at ...
0
votes
0answers
31 views
Socket buffer and purpose of SO_RCVBUF [closed]
I'm trying to figure out what the SO_RCVBUF actually does.
Referring to the Linux kernel, it seems that the value specified with this option is just assigned to a variable (sk_buff.rcvbuf), which ...
1
vote
1answer
60 views
Per-packet round-robin load balancing for UDP
I need to load-balance UDP traffic between a number of "realservers" and do it in a truly round-robin fashion. I've started with keepalived, but unexpectedly discovered, that LVS treats UDP traffic as ...
0
votes
2answers
64 views
Traceroute, ICMP, UDP and TCP
When does traceroute use TCP? Or does it just use UDP, also why does Traceroute use UDP on MacX and ICMP on windows? I thought ICMP just contains a message saying what caused the error of a packet and ...
-4
votes
0answers
27 views
How FaceBook Chat understand packet loss and errors? [closed]
We know that Facebook chat use UDP connection like other chat servers.
But when you send a message there,if the other client doesn't recevied our message a ! appear at the beginning of failed message.
...
1
vote
0answers
24 views
Nat Traversal, peers unable to communicate
I'm currently working on a project that requires NAT traversal but I seem to be running into difficulty. I have the following setup running for testing:
R1, Verizon Fios router connected to the ...
0
votes
0answers
53 views
Serious Packet Loss on UDP using Amazon EC2
I am using ec2 to host a udp TURN server for SIP purpose. Anyway I get a lot of packet loss during voice call, so I did a udp performance test using iperf util.
Result:
[ ID] Interval Transfer ...
0
votes
0answers
26 views
How to enable the UDP option in the socks server antinat?
How to enable the UDP option in the socks proxy server Antinat? It's running but it only supports TCP. It's not listening on UDP.
I've tried another socks server Dante, but failed to configure it.
0
votes
1answer
44 views
How do I increase UDP Recv-Q
I have a gigabit connection that is not fully utilized but I am getting packet receiving loss.
When I do netstat, it shows the Recv-Q sometimes maxes out at 262656 during heavy traffic.
Proto Recv-Q
...
2
votes
2answers
66 views
What is the lowest udp source port for puppet dns queries?
On CentOS 6.4 and 6.3 I have seen puppet regularly use ports below 32768. This is contrary to the setting for kernel-assigned ports according to:
cat /proc/sys/net/ipv4/ip_local_port_range
32768 ...
1
vote
1answer
78 views
UDP packets dropped
A host sends UDP broadcast, but its UDP packets are not received by any other hosts in the same subnet. However, its TCP traffic with others hosts are OK. I observed this using tcpdump.
Could it ...
1
vote
1answer
53 views
Trouble with VPN Tunnel
How to direct a UDP Packet through a VPN tunnel?
The router in question dose not have any features that would allow a UDP flooding or broadcasting, so for this project I am shooting in the dark, any ...
0
votes
1answer
109 views
openvpn tcp or udp (specific situation, reliability-layer collisions)
My question is whether to use TCP of UDP for my openVPN connection.
I've set up a simple network for a startup company that allows users from the outside to acces the network via an openvpn server (in ...
0
votes
1answer
41 views
Is multicast appropriate for sending a copy of a video chat to a server?
I am creating a p2p video chat app using the libjingle/WebRTC code. I would like to collect a copy of these video conversations on our server for users to watch later - but I don't want to suck up too ...
1
vote
0answers
99 views
UDP socket receive buffer size change on RHEL6.3
Our system used to work on RHEL5.3 And the socket receive buffer size is 64k. And that works fine. We can get message size up to 64k on UDP socket.
But after system upgrade, it is running on RHEL6.3 ...
0
votes
0answers
203 views
OpenVPN - Connection refused Unable to obtain Session ID
I have just setup an OpenVPN server with freeRadius following these guides, so my config etc is basically like on the guides:
https://safesrv.net/install-openvpn-on-ubuntu-11-10/
...
3
votes
1answer
257 views
Is it possible to duplicate a UDP unicast stream with iptables?
I have a proprietary system which transmit a udp video stream from unit #1 (192.168.1.1) to unit #2 (.1.2). I can't make changes to this system, and I'm trying to clone this udp stream so I can access ...
0
votes
0answers
38 views
Max number of concurrent UDP clients on openVPN on Windows?
Like it is mentioned that openVPN can handle 60 concurrent TCP clients on Windows.
How many concurrent UDP clients can be handled by openVPN on Windows Server 2008/2012 ?
0
votes
0answers
91 views
IPSec port blocking rule doesn't block packets? (Windows 7)
I'm trying to set up an IPSec rule in Windows 7 to block UDP traffic on a specific port (31069 in this example) on a particular network interface. (The plan is to allow it on a secondary NIC, but for ...
2
votes
2answers
94 views
Solaris doesn't know which MAC address to use to send an UDP multicast message
I have a pair of Solaris 10 boxes which are supposed to send multicast UDP packets to a group of hosts. One of them works just fine, whereas the other one does not.
The problem with the second ...
0
votes
1answer
170 views
Countermeasures versus incoming DNS reflection attack
i am currently experiencing a DNS reflection attack towards my server.
I am getting a massive amount of answers via UDP from Port 53 that my server has never asked for:
02:53:57.626156 IP (tos ...
1
vote
1answer
117 views
Tool for forwarding UDP packets Windows
Windows Server 2008
I use portproxy interface to forward traffic , but I looked into the msdn page and I noticed it doesn't support udp protocol .
protocol
Specifies the protocol to use. ...
0
votes
0answers
84 views
Cannot see an EC2 VPN server from another EC2 instance
I'm using openVPN to connect to one EC2 instance from another. The client cannot see the server, however, despite that servers outside of AWS can see the server and successfully negotiate with it.
...
1
vote
2answers
198 views
How does SSL VPN (openvpn) connect via UDP?
I need to test whether an OpenVPN Service (ssl-vpn) is listening on a specific IP address and port from a linux box. I'd like to do that with a bash script or some code in python or c/c++ but that's ...
1
vote
1answer
145 views
port forwarding to access services on servers behind NAT
I have some security camera systems in different locations, each location does have internet, the ISP is NATing all the IPs so theres no way to open ports to my systems.
My solution was to rent a VPS ...
1
vote
3answers
94 views
DDOS protection from ISP side, UDP protocol, whitelist
Is it possible to ignore packets from ISP side which are incoming to my server?
Is possible this kind of situation ? :
I have white list of IP addresses.
I continually update white list and sends it ...
2
votes
0answers
411 views
Forwarding udp ports iptables packets “lost”?
I have a Linux router (Debian 6.x) where i forward some ports to internal services.
Some tcp ports (like 80, 22...) are OK.
I have one Application listening on port 54277udp.
No return is coming from ...
0
votes
1answer
205 views
UDP packets to IP addresses other than specific ones not arriving and not shown in Wireshark
I'm writing a service using UDP, but I can't manage to reply to the client.
When sending to the client via the DHCP-assigned IP (192.168.1.143) Wireshark shows no sent packets. The server receives ...
-1
votes
1answer
233 views
Difference between sending data via UDP in Bash and with a Python script [closed]
I'm on a Centos box, trying to send a UDP packet to port 8125 on localhost. When I run this Python script:
import socket
sock = socket.socket(socket.AF_INET, socket.SOCK_DGRAM)
sock.sendto('blah', ...
0
votes
2answers
95 views
nmap scan only state of port
Is it possible with nmap to check only the state of a port whether- open, closed or filtered and NOT the services behind it?
The aim is to speed up scan results. Since UDP scan is also involved it is ...
4
votes
1answer
297 views
possible UDP attack on BIND?
hello everyone,
i was surprised last month when my EC2 instance (ubuntu precise server), that is supposed to be under the free tier still, accumulated lots of traffic... today, while checking my ...
0
votes
2answers
408 views
Problems with MDNS flooding on port 5353 UDP
I am running into a big issue at a small network i manage. This network is an Apple network, with airport extremes, expresses, mac book pro's, imac's, ipads, iphones etc...
I went to add something to ...
0
votes
2answers
775 views
iptables rules for botnet (UDP flood) protection
I'm currently experiencing a massive UDP attack on my server. I host a couple of gameservers, mainly Tf2, CS:GO, CS 1.6 and CS:Source, and my 1.6 server is being flooded.
I tried different rules in ...
3
votes
1answer
227 views
UDP Packet Size.. max, ping failing to 3G.. Recalcitrant software vendor
We have a network of 330 clients (Service Vans) connected via 3G to our central office. Currently these clients are connected via a small ruggedized 3G router that establishes the 3G connection and ...
1
vote
1answer
157 views
Multicast in private LAN with different subnets
after i read
Multicast IP Addresses
and
Multicast accross the subnets
I am confused.
Configuration: I have two devices in the same network. They may not be in the same Subnet, but ...
0
votes
0answers
312 views
UDP multicast streaming of media content over WIFI [closed]
I am using vlc to stream media content over wireless network in scenario like this (from content streamer to stream receiver client):
The bandwidth of wireless network is 54 Mb/s and UDP stream's ...
-3
votes
3answers
58 views
Two-way UDP on varying-IP networks
I've heard that on some corporate networks, outbound traffic from the same user can hop around different "from" IPs. Does that break two-way UDP, or do the networks only act that way for TCP?
If it ...
-1
votes
1answer
82 views
Force DNS resolution to use TCP [Mac] [closed]
My comcast internet connection has been giving problems in DNS resolution, and I am guessing the reason is a probably broken or limited UDP. I am currently working around it by tunneling over TCP ...
1
vote
1answer
476 views
Why does VPN IPSec client use UDP?
The VPN I use on my home Windows computer to connect to my company's servers is a Cisco client. The client is configured to use "IPSec over UDP (NAT/PAT)".
Why would you use UDP, an "unreliable" ...
0
votes
2answers
1k views
Why is UDP slower than TCP on Ubuntu Server?
I transfer data between two Ubuntu Servers (12.04) via iperf on 1Gb LAN.
iperf -s <-> iperf -c <addr> -n2G
TCP speed = 925 Mbits/sec
iperf -su <-> iperf ...
1
vote
1answer
99 views
UDP flooding multiple servers [duplicate]
Possible Duplicate:
What are the best techniques for preventing denial of service attacks?
What do you suggest?
Being UDP flooded as I write to multiple servers in different data centers ...
0
votes
1answer
104 views
Can NAT port change dynamically in an active session?
I am facing an issue, having client server application where client application is sending UDP data frequently to server and server redirecting back to the client. But in a few cases I am not getting ...
3
votes
1answer
216 views
HTTP, TCP, UDP and connectionless
I am a bit confused with HTTP lately. Some facts are that TCP can operate connection orientated or connectionless this I understand. TCP though is connection-oriented while UDP is connectionless ...
2
votes
1answer
362 views
Tunnel only one program (UDP & TCP) through another server
I have a windows machine at home and a server with debian installed.
I want to tunnel the UDP traffic from one (any only this) program on my windows machine through my server.
For tcp traffic this ...
0
votes
1answer
191 views
Broadcasts from guest machine not reached host machine
I have an application that sends UDP broadcasts to some port, for example 11000 (BROADCAST_APP) and another application that listens the 11000 UDP port(LISTENER_APP). The apps works well on the ...
0
votes
1answer
659 views
Too much traffic on UDP suspecting bind miss-configuration
A server generates over 600GB of monthly traffic on UDP port (while http is under 1GB), so I ran tcpdump command and I see many (over 10/second or so) fast dns related commands/traffic that looks like ...
1
vote
4answers
93 views
Just one client bound to address and port: does it make a difference broadcast versus unicast in terms of overhead?
Scenario:
I am implementing failed over for a network node, so my idea is to make the master node listens on a broadcast ip address and port. If the master node fails, another failover node will ...
1
vote
0answers
180 views
Does hole punching require a UDP rendezvous server Or could it be a TCP one?
I'm trying to get my head wrap around this issue...
I would like to connect two users...
Those users are already connected to a TCP server, which is aware of both public ip and connection TCP port.
...
