Networking refers to the technologies and techniques that enable the interconnection of devices and applications allowing them to communicate electronically.

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9
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2answers
14k views

How to alter the global broadcast address (255.255.255.255) behavior on Windows?

Desired behavior When an application sends a packet to the global broadcast IP address 255.255.255.255, I would like that the packet be sent to the Ethernet global broadcast address ...
0
votes
1answer
37 views

127/8 address is not passed to IP stack?

I send IP/UDP frames using raw sockets with destination IP address from 127/8 range - e.g. 127.0.0.6. So, packets are sent over the network OK (checked using tcpdump on the target device). But on ...
2
votes
1answer
173 views

Assign physical interface to docker exclusively

I would like to run a high performance network test in a docker container, and do not want the overhead of bridging (so pipeworks won't work AFAIK). I would like to assign (in addition to the normal ...
0
votes
1answer
28 views

Time Between successive DNS queries.

Using a PC running Ubuntu 14.04. I'm testing web browsing using a very low speed and low data rate link. My system is congested with DNS queries (and other types of packets like TCP re-transmission). ...
1
vote
1answer
33 views

When connecting to localhost, does a full SYN, SYN-ACK, ACK handshake still occur?

This question is addressed, primarily for Linux. While I could find the answer myself, I'm hoping someone out there just knows the answer implicitly and can save me some time. If I'm connecting to a ...
1
vote
1answer
566 views

Connections stuck in ESTABLISHED state

On a Debian machine I'm having several connections hanging for about 8 hours: tcp6 0 0 192.168.1.35:56312 88.191.79.XXX:25 ESTABLISHED tcp6 0 0 192.168.1.35:43352 ...
0
votes
2answers
73 views

Is there any disadvantage to putting a modem in bridge mode

In order to prevent the need of port forwarding and double natting I plan to put a modem into bridge mode. Are there any side effects or problems that could come of placing a modem into bridge mode in ...
1
vote
0answers
357 views

Event id 4227 tcp/ip warnings on Windows 7

We're deploying a new image out to the field, and we're seeing tcp/ip event id 4227 warnings periodically throughout the day (1-3 a day). The event message reads as follows: TCP/IP failed to ...
0
votes
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
votes
1answer
21 views

On a Linux NAT host, late duplicate segments cause connection resets

https://www.cloudshark.org/captures/6f185eb12e97 172.30.5.1 Linux vm with bridged networking, running on another server, VM has RFC1918 address only 144.76.103.194 Linux host ...
0
votes
1answer
31 views

Can't connect php to SQL server, error:0

I've set up an internal Ubuntu 14.04 LAMP server. I can access SQL when using Putty, but when I try to connect via php script all my pages were blank... Then I tried to debug it by simply connecting ...
0
votes
0answers
13 views

SCOM manual dashboard creation displaying blank for network devices

I have successfully installed SCOM 2012 r2 (roll up installed) and able to display all the intended network devices in default dashboard. Now i am going to create manual dashboard for network ...
0
votes
1answer
66 views

How to connect custom network namespace to root network namespace?

I would like to connect the root network namespace to my custom network namespace in my Ubuntu box. Here is my network diagram: Basically my custom network namespace is the one who control the vm ...
0
votes
1answer
53 views

Windows Server 2008 R2 Standard Dropping Packets

I am seeing a strange problem with my WS2008R2 server I believe is related to networking. The symptom is that 6% of all attempts to ping the server using tcp fails. For example, from another machine, ...
5
votes
4answers
2k views

Mysterious “fragmentation required” rejections from gateway VM

I've been troubleshooting a severe WAN speed issue. I fixed it, but for the benefit of others: Via WireShark, logging, and simplifying the config I narrowed it down to some strange behaviour from a ...
0
votes
1answer
12 views

Replicate Partition Over Network

Is there a way, in Windows Server 2012 to replicate two same-size partitions over the network in real-time, preferably at driver level (not user-land)? I am asking for two Hyper-V servers. There is ...
0
votes
1answer
78 views

Linux: nslookup and dig resolve $HOSTNAME, but ping doesn't

In our private network we have a Consul service discovery server (10.241.232.14) that provides a DNS interface (port 8600). We would like to set our common DNS servers to forward some queries to the ...
0
votes
0answers
4 views

TPM Drive Encryption / Network Profile

I have the following situation: I have an old application that cannot be rewritten for various reasons that I can't go into. Just noting that refactoring the source of the problem is a total no-go. ...
1
vote
0answers
17 views

Can't connect to selenium grid on VM?

I have a VM on the same network as my computer. I can remote into the VM and open up the selenium grid console (http://(ip):4444/grid/console) and it appears to be working fine. When I try to open ...
0
votes
0answers
25 views

Web servers configured to use 'localhost' not accessible inside network

What would cause an Ubuntu Server 14.04 LTS machine to lose the ability to use 'localhost' in web-server configurations? If I replace 'localhost' with the machine's static, internal IP address ...
0
votes
0answers
22 views

Gateway to internet on CentOS 6

I have 2 CentOS 6 linux servers say hostnames cent001 and cent002 cent001 has 2 Nic's 1 Bridged and 1 Nat cent001 is able to ping google server 8.8.8.8 with the help of bridged NIC cent002 has only ...
2
votes
3answers
864 views

The requested operation requires elevation

We have about 15 PCs on our network. I can make changes to all the PCs except one. I keep getting the message "The requested operation requires elevation". When I try to run a program as an admin, ...
0
votes
0answers
59 views

Windows 7 Network Adapter Periodically Shows Disconnected

Description: My company is currently working on a project that utilizes 2 servers, and 1 client, running on an isolated network. Periodically, one or both of the servers will lose network ...
0
votes
1answer
1k views

VPN - local and remote networks IP collision

I have created a VPN connection in Windows using the New Network Connection wizard that comes with Windows. It works without problems in most places, but there is one concrete place where, despite ...
5
votes
1answer
5k views

Unexpectedly shrunk window

I run a major media upload/download site and I noticed these: Is this serious or background noise due to the big file sizes and is there any tweaks I can add to /etc/sysctl.conf to improve and ...
0
votes
1answer
17 views

ipv6 address configuration on serial interfaces

I tried to configure Ipv6 static routing on three routers, I configured ipv6 addresses on all three routers using ipv6 address auto config, The middle router have been configured with different global ...
0
votes
0answers
23 views

Windows 7 behavior on network link between SonicWALL and pfSense

I have two networks behind two different firewall at the same site. I have linked them together by using a spare interface on each device. Network 1 - pfSense 10.0.10.0/24 Network 2 - SonicWALL ...
1
vote
1answer
232 views

Command to set dscp / ToS value on outgoing packets for OS X Mavericks?

I want to set a certain DSCP (or ToS) value on all packets sent over port 22. I have an iptables command to do so, but Mavericks only has the equivalent of pfctl and I can't figure out how to ...
1
vote
1answer
34 views

Hyper-v ISCSI Network Setup

I have Hyper-v installed on Windows Server 2012 R2. We are using 2 x Dell R730xd's with 8 NICS (4x10GigE 4x1GigE) per host. I would like to dedicate 2 NICS to our ISCSI network, however I am unsure ...
2
votes
3answers
6k views

Cisco ASA rewriting SMTP traffic to prevent mail sending

We have a Cisco ASA 5505 (version 8.0(4)) that is preventing outbound SMTP traffic; testing with telnet shows connections on port 25 are having everything converted to *s while the same does not ...
6
votes
2answers
8k views

Finding (and stopping!) Rogue Devices from HP Procurve

We seem to have a problem with rogue devices on our network. From DHCP (on Win2003), I can see names of devices that are clearly not ours. From the name, I suspect it's a wireless AP (WGR614 looks ...
1
vote
2answers
177 views

Unable to locate DHCP Server

I am supporting a mixed Mac OSX and Windows environment. There is a rogue DHCP Server which seems to be providing the IP-addresses to Mac systems on the network. I have used both ZenMap and Wireshark ...
8
votes
4answers
9k views

Docker containers can't resolve DNS on Ubuntu 14.04 Desktop Host

I'm running into a problem with my Docker containers on Ubuntu 14.04 LTS. Docker worked fine for two days, and then suddenly I lost all network connectivity inside my containers. The error output ...
58
votes
11answers
127k views

How do I find if there is a rogue DHCP server on my Network?

What's the best approach towards determining if I have a rogue DHCP server inside my network? I'm wondering how most admins approach these kinds of problems. I found DHCP Probe through searching, ...
0
votes
0answers
37 views

Cannot ping gateway (Intervlan routing)

I have two switchs cisco 2960 (sw-120 and IDF1-SW) and router cisco 1841 (IDF1-R). fa0/24 at sw-120 connected via fa0/7 at IDF1-SW fa0/1 and fa0/24 at IDF1-SW switched to trunk mode fa0/24 at ...
0
votes
0answers
26 views

Remote OSX Server does not accept TCP connections from abroad?

Long story short: I am able to connect to the box (which is located in my office) from home. Two different ISP providers. On the contrary, my friend from the US is not able to access it - the ...
0
votes
0answers
49 views

High bandwidth, high latency file transfer in Windows

We're attempting to transfer some SQL backup files (~5-75GB each) across a network with about 70ms latency between two servers (Server 2012 R2 - same domain) across a VPN connection. Both servers are ...
1
vote
2answers
4k views

How to connect to a Netgear SRW224G4P serial console port?

I have two Netgear SRW224G4P switches with serial console ports. I'm using a Sabrent USB 2.0 to serial cable adapter with a female-to-female serial cable. I'm running Windows 7 64-bit and using putty ...
0
votes
0answers
17 views

Configuring additional static IP for Guest Machine

I am trying to bind my Guest machine to respond on my second public IP address. Sometimes it works automatically by DHCP just by configuring my MAC address, sometimes it doesn't work at all. All I ...
7
votes
7answers
11k views

How to detect rogue WIFI routers on a network?

My client recently changed their network policy so now all WIFI routers are disallowed from the network. They said they would be running some scans and that they would be able to find "rogue" WIFI ...
5
votes
8answers
4k views

What equipment do real ISP's use? [closed]

In a dormitory of 550 residents, people often mistakenly set up DHCP servers for the whole network by plugging in their private Wi-Fi routers wrongly. Also recently, someone mistakenly configured ...
5
votes
4answers
2k views

Why do VPN connections break when I sleep my computer? [closed]

On the limited (Cisco) VPN systems that I've used, the VPN connectivity is broken when my computer is put to sleep and must be re-established on wakeup. Is this a necessary property of VPN?
-1
votes
1answer
804 views

Ubuntu 10.04 server change ip

I have ubuntu 10.04 server configured to ip address x.x.x.200 and also have windows server 2003 with ip address x.x.x.100 (already setup as www.some-domain.com) Currently i trying to shutdown windows ...
2
votes
0answers
48 views

Stream IPTV through SSL VPN

I have a question about streaming IPTV through Cisco ASA5510 ssl vpn. My current setup at the moment is: Public - firewall (asa5510) - L3 switch - L2 switch But my iptv source feed is coming to L3 ...
6
votes
1answer
193 views

4X10GB Bonded NIC - only producing 4-5GB throughput

I have Two HPBL685c G6 blade servers running Ubuntu 15.04 Each server has 4X10GB NIC 2x10GB NIC are connected to a single VirtualConnect 10/10G Ethernet module The other 2x10GB NIC are connected to ...
1
vote
2answers
54 views

site-to-site vpn tunnel - does hardware matter? [closed]

I have been tasked with setting up 4 offices and connecting them all together so they can be on the same network. Does hardware really matter or could I build a decent machine in the low $1000's and ...
1
vote
1answer
938 views

MySQL command appends '@localhost' to username

I just can't seem to figure this one out. I want to use the command line to connect to a MySQL database residing on another server. I went ahead and created the username and password for the user. ...
0
votes
1answer
17 views

How to manage access to nodes in a cluster?

I am about to set up a server cluster for our company's web applications. At the beginning there will be 3 hardware servers in Proxmox HA setup in a remote datacenter running about 20-30 VMs all ...
-4
votes
1answer
26 views

How is my Mac Mini and Windows PC communicating? [closed]

So I just bought a Mac Mini that I am using as a build server for developing iPhone apps. My I plugged the Mac Mini in, connected it to my Wifi Router, installed a third party piece of software, ...
0
votes
3answers
2k views

Hyper V with local DNS and forwarding - nslookup works but ping gets general failure

I have a Hyper-V virtual machine configured with its own DNS manager and entries for testing. The VM DNS manager is setup to forward all other requests to the "regular" DNS servers. This all used to ...