i have a big problem. I need tranfer a lot of files by a server to another server, but the second server isnt a local server. If i tranfer by a local server i cant 100mbs but if i send for another server out the speed is 2mbs. my network is 1gbs. I use a command line 7z.
If your servers are (as you wrote) on the same network and connected through the same line you are most likely to have a network connection problem.
I've often seen that the duplex settings of network cards are not set up correctly which leads to a lot of collisions.
Check your network card settings and try to force for example 100mbps full duplex.
I work for a company where this happens daily when trying to connect IBM network cards with Cisco switches. Have a look here how to set up duplex settings: https://superuser.com/questions/86581/how-do-you-check-the-current-duplex-value-of-a-network-card-set-to-auto-negotiat.
If this doesn´t help you might be better off asking at superuser.com
I need to test the performance of application running on localhost as if it were in the online environment. I mean the performance test conducted by the network traffic simulation, limited bandwidth simulation, or other parameter as if it were online.
Could Apache Ab do the simulation?
We've used Charles and Firefox Throttle in the past to simulate slow networks.
Why can't you connect to a different PC, or even use a virtual machine and rate limit the virtual network connection?
Yes, but you will need to connect to your application by IP address, not "localhost" or 127.0.0.1. Typically for web applications (HTTP) I use Fiddler which can simulate limited bandwidth, but only if you connect as I have noted. Other bandwidth limiters for non-HTTP I'm not sure/aware of.
Ab won't simulate low level network errors. If you're on linux, you can simulate some networking with 'tc'. See http://www.kdedevelopers.org/node/1878 for a small example.
You can set up a local tunnel to expose your localhost to the world, using Ngrok. From there you can use any number of online performance tools
You can throttle bandwidth via Chrome Dev Tools
I am trying to find the most used Network card on windows 200 or XP. I planned to obtain the number of packets sent trough each NIC to determine the main NIC.
I thought IP Helper might give me this information but also it looks like the functions in IP helper only give stats for all interfaces. I know this can be done. Any ideas?
Many Thanks...
Have you looked at WMI ? Here's an example of interrogating the set of network adaptors. Note that it includes stats such as the number of forwarded packets for each adaptor.
You could use from any number of available packet sniffer programs out there: Top Packet Sniffers
Also look here: wiki
I'd like to sell headless Linux servers to SOHO users. Typically, they'll have a DHCP-capable ADSL modem cum switch to which they'll connect their workstation and the server.
In order to just show up with the server, I need to find a way to just plug the server into the switch to get an IP address from the modem, and then have the server broadcast its adresse so I can then connect to it with Putty from the workstation.
I thought about using Samba to broadcast a message using the Messenger Service, but unless I'm mistaken, this only works if the two hots are configured to use the same workgroup/domain.
Do you know of way to get the server's IP address from the workstation?
Thank you for any tip.
Take a look at UPnP and zeroconf services like Apple's Bonjour.
I'd probably suggest using the normal approach for switches and modems as you are treating your device as an appliance, i.e. set a default IP 192.168.0.1, and connect to that to then configure the device into the local infrastructure.
I don't know of any good solutions.
Some DHCP servers will register the name you send in the request - then give that name in your setup instructions. But I suspect home user DSL routers aren't in that category.
Maybe you could ship a tool on CD that does arp requests to get the IP address? (Given the MAC address printed on the box)
Broadcast packets periodically on some arbitrarily chosen UDP port, and build some client software to listen for those packets.
I often run into problems where I can't get something to connect to something else. I usually forget to check something obvious. Can you help with:
A tip/technique for diagnosing a connection issue
The name of a tool or application that can help (and the situation in which it's useful)
I know the question is a little non-specific, but hopefully the answers can form a useful starting point for anybody who's stuck trying to get computers/programs talking to each other.
Please can you give one answer per answer so the best ones can be voted up.
Simple checks to run when debugging network problems:
Has each machine got an IP address, Go to command prompt and run ipconfig. Key things to check here are the interfaces and ensuring the appropriate ones have IP addresses.
Check both machines IP addresses are in the same range and subnet if you are running it on an internal or Virtual network.
Try pinging each machine from the other to see if they can communicate with each other. Note that some firewalls will block ping requests.
If Pinging fails then check to see if firewalls are active. If the communication is within a 'safe' internal network then try disabling the firewalls and re-pinging.
If the connections are over a wireless network then check signal strength.
If pinging fails and you are connecting through several networks then try running a tracert to see at which will may show you where on the network the connection is failing.
If you are able to ping but not connect then check firewall settings and network connection settings. Windows 2000+ has the capability of setting port an ip access on a connection properties.
Try drawing a network diagram of the connections to help in visualising the problem.
If you are connecting through routers, firewalls and loadbalancers then check that all devices are not tied to any specific ip addresses and that the IP address redirection (if in place) is correct. Also check any NAT logs to see if connections are being received and properly re-directed.
Wireshark
Latest versions of ProcMon
netstat
Wireshark www.wireshark.org
Wireshark is a network protocol analyzer for Unix and Windows.
Features:
Deep inspection of hundreds of protocols, with more being added all the time
Live capture and offline analysis
Standard three-pane packet browser
Multi-platform: Runs on Windows, Linux, OS X, Solaris, FreeBSD, NetBSD, and many others
Captured network data can be browsed via a GUI, or via the TTY-mode TShark utility
The most powerful display filters in the industry
Rich VoIP analysis
Read/write many different capture file formats: tcpdump (libpcap), Catapult DCT2000, Cisco Secure IDS iplog, Microsoft Network Monitor, Network General Sniffer® (compressed and uncompressed), Sniffer® Pro, and NetXray®, Network Instruments Observer, Novell LANalyzer, RADCOM WAN/LAN Analyzer, Shomiti/Finisar Surveyor, Tektronix K12xx, Visual Networks Visual UpTime, WildPackets EtherPeek/TokenPeek/AiroPeek, and many others
Capture files compressed with gzip can be decompressed on the fly
Live data can be read from Ethernet, IEEE 802.11, PPP/HDLC, ATM, Bluetooth, USB, Token Ring, Frame Relay, FDDI, and others (depending on your platfrom)
Decryption support for many protocols, including IPsec, ISAKMP, Kerberos, SNMPv3, SSL/TLS, WEP, and WPA/WPA2
Coloring rules can be applied to the packet list for quick, intuitive analysis
Output can be exported to XML, PostScript®, CSV, or plain text.
work the OSI model from the bottom up
Physical (Do you have a network adapter/connection)
Link layer (arp, ethernet port blocked by network team (I've seen this where locked down environments see two MAC addresses coming from one workstation port and shut down the port)
Network layer (ipconfig, tracert, ping,)
Do you have a network address (DHCP, fixed)
Are you on a proper subnet/have routing between subnets
Is something in the middle blocking you
firewalls, routing tables
When in doubt, check to see if the windows firewall is messing with your communications. 8 times out of 10, it's at fault.
Using tracert is a good start to see how far along the chain you are getting.
For virtual machines it's usally a good idea to make sure you have the loopback adapter set correctly in the Host os.
Most frequently used tool is the ping. It can be used both to test your connection and the availability of a target
Second tool is the tracert if you want to see where the packets get lost.
For more advanced debugging I use the following tools: nmap, wireshark, etc.
Windows has a netstat utility which is pretty similar to the Unix netstat and can do a number of different things that might help you solve network issues.
Random example:
netstat -r displays routing information
netstat /? for usage information
Since you said you're using 2 virtual machines I would hazard a guess that both machines are setup in a NAT configuration (rather than a unique network device) -- In the NAT configuration, neither machine would (typically) be able to ping the other.
If you're familiar with the command line, you can try the "netstat" command.
You can also try "arp -a" to list all the IP/MAC addresses known to your PC.
The "tracert [ip address]" command will show you how many gateways/routers your packets jump through on their way to their destination. (This is probably not helpful if both machines are on the same network, though.)
And don't forget to check your Windows firewall settings.
Otherwise, if you want to get down and dirty, you can try the packet sniffer known as Wireshark: http://www.wireshark.org/ (aka. Ethereal)
Pull the network cable out
If you can get some communications to a device (eg a ping), but can't get your program to talk to a service on the computer. Then, try pulling the network cable out and see if the ping stops. This will verify you're communicating with the computer you really think you are.
On windows i user PortQueryUI : http://www.microsoft.com/en-us/download/details.aspx?id=24009
DNS activity: Portable DNS Cache and Firewall;
General network activity: Wireshark, Network Monitor;
Windows utilities: ping, netstat, nslookup.
You need to be use the process of elimination, for example if you can ping the ip address but not the hostname then there's DNS issues. If you can ping the system but not connect to a share etc.
DNS out of sync
If you're using a virtual machine and you perform a roll-back on it, then it could become out of sync with the DNS (Domain name server). Try to remove and re-add the machine to the domain, or if you've got access to the DNS machine, then get it to flush its cache.