I have three cases when using Skype on Windows is most probably the cause of Internet connectivity interruption on the computers in question.
Two of computers affected run Windows 7 Eng 64-bit, one runs Windows 8 Eng 64-bit, latest updates installed.
In two cases (one of Windows 7 computers + Windows 8 computer) after using Skype for some time Internet connectivity is broken, namely
All local network connectivity isn't affected
Traffic that should be
passed outside local network, doesn't leave the computer (when
recording traffic on gateway, not a single packet comes from the
computer in question)
"route print" displays normal routing table
(no duplicate routes/other routing errors)
Uninstalling/Reinstalling Skype in the above cases cured the problem immediately.
The third case (Windows 7): using Skype to generate much traffic (e.g., holding audio/video conference) causes short-time Internet connectivity loss. As in earlier mentioned cases, local connectivity isn't lost, but all outer hosts, when tracert'ed, are displayed as available in single hop, yet they do not respond. In this case the problem heals by itself.
Linux-running computer serves as gateway to Internet (NAT).
Checked and adjusted already: routing, DHCP/DNS settings, firewall rules, malware scanning (nothing found), checking hardware, replacing patchcords/network cards, all for no avail. Switching "UPnP" in Skype off in the latter case made no difference, the first two didn't yet exhibit the mentioned problem again after disabling UPnP.
Skype version used: the latest one, available from Skype.com. The rest of systems running Skype, on Windows or not, do not report similar problems.
Question: are there known Skype-inflicted connectivity problems in Windows, and, if yes, what are ways to solve them reliably?
Skype uses port 80 by default. You could try changing the default port to something else that doesn't already have a service running on it.
Related
By default, XCode is setup to download updates associated with the various documentation and API libraries available to the application. This can be disabled from the XCode preferences screen. However, I'd prefer not to disable the automatic updates but, rather, prompt me to start the updates so that I can potentially dismiss them for download at a later time.
My reasoning is because I primarily work through a network connection that gains access to the internet through a 4G wireless hotspot that gets hit by overage fees. In fact, I'm connected through this device, to the internet, about 90% of the time I'm working on my Mac. When I need to download any form of large software update, I always take my Macbook to an open, direct-connect source to the internet and let it do what it needs to do.
This works fine for most software, but not XCode.
I want my updates to remain automatic (so that I am at least informed that there is an update available,) however, I'd like to have the choice whether to initiate them or not.
Is there something that I can do to make XCode ask before downloading?
A QUICK NOTE
I know how we technical minded folk are-- half of you are still wondering why I work off of a 4G hotspot and want to fix that problem, instead of the one I asked. (Yes, I tend to think this way too.)
However, I work in an environment that has an IT department that adamantly refuses to allow any operating systems, other than Win XP and Win 7, onto their network. The Engineering team (which I work for) has to have an internet connection and an internal network for storing and backing up data and we are developing iOS software that is integrated with our products. This is obviously problematic since we need to use Macbooks to do our work.
Our solution to this dilemma has been to setup our own, small LAN and our only way of getting internet access is through cellular WiFi. All WiFi ISP plans that are available in our region are tier-based and overages are charged (at a reasonable rate) when we use more than our allotment of data. We don't mind going over our quota, however, we need to keep it reasonable. Automatic updates like this can start to take a huge hit on our network when a few of us have to download a few GBs of data each month.
Software like LittleSnitch might be the best solution (firewall).
In case Xcode tries to update itself, the dialog below shown.
Now you can simply Allow or Deny the connection.
This way you can accurately control all connections (and your privacy).
Other applications might also consume quite some bandwidth.
P.S.
Why not connect a cheap XP box to the network,
which shares the internet connection to all Macs?
The LAN which has about a half dozen windows xp professional pcs and one windows 7 professional pc.
A jet/access '97 database file is acting as the database.
The method of acccess is via dao (DAO350.dll) and the front end app is written in vb6.
When an instance is created it immediately opens a global database object which it keeps open for the duration of its lifetime.
The windows 7 machine was acting as the fileserver for the last few months without any glitches.
Within the last week what's happened is that instances of the app will work for a while (say 30 mins) on the xp machines and then will fail on database operations, reporting connection errors (eg disk or network error or unable to find such and such a table.
Instances on the windows 7 machine work normally.
Moving the database file to one of the xp machines has the effect that the app works fine on ALL the xp machines but the error occurs on the windows 7 machine instead.
Just before the problem became apparent a newer version of the app was installed.
Uninstalling and installing the previous version did not solve the problem.
No other network changes that I know of were made although I am not entirely sure about this as the hardware guy did apparently visit about the same time the problems arose, perhaps even to do something concerning online backing up of data. (There is data storage on more than one computer) Apparently he did not go near the win 7 machine.
Finally I know not very much about networks so please forgive me if the information I provide here is superfluous or deficient.
I have tried turning off antivirus on the win 7 machine, restarting etc but nothing seems to work.
It is planned to move our database from jet to sql server express in the future.
I need some suggestions as to the possible causes of this so that I can investigate it further. Any suggestions would be gretly appreciated
UPDATE 08/02/2011
The issue has been resolved by the hardware guy who visited the client today. The problem was that on this particular LAN the IP addresses were allocated dynamically except for the Win 7 machine which had a static IP address.
The static address happened to lie within the range from which the dynamic addresses were being selected. This wasn't a problem until last week when a dynamic address was generated that matched the static one and gave rise to the problems I described above.
Thanks to everyone for their input and thanks for not closing the question.
Having smart knowledgeable people to call on is a great help when you're under pressure from an unhappy customer and the gaps in your own knowledge mean that you can't confidently state that your software is definitely not to blame.
I'd try:
Validate that same DAO and ODBC-drivers is used on both xp- and vista machines.
Is LAN single broadcast domain? If not, rewire. (If routers required make
sure WINS is working)
Upgrade to ms-sql. It could be just a day of well worth work, ;-)
regards,
//t
I am trying to set up a clean vm I will use in many of my devs. Hopefully I will use it many times and for a long time, so I want to get it right and set it up so performance is as good as possible. I have searched for a list of things to do, but strangely found only older posts, and none here.
My requirements are:
My host is Vista 32b, and guest is Windows2008 64b, using Vmware Workstation.
The VM should also be able to run on a Vmware ESX
I cannot move to other products (VirtualBox etc), but info about performance of each one is welcomed for reference. Anyway I guess most advices would apply to other OSs and other VM products.
I need network connectivity to my LAN
When developing/testing, guest will run several java processes, a DB and perform some file I/O
What I have found so far is:
HOWTO: Squeeze Every Last Drop of Performance Out of Your Virtual PCs: it's and old post, and about Virtual PC, but I guess most things still apply (and also apply to vmware).
I guess it makes a difference to disable all unnecessary services, but the ones mentioned in 1 seem like too few, I specifically always disable Windows Search. Any other service I should disable?
You can try to run the CD/DVD through vLite to remove unwanted crap. I'm not 100% sure if Windows 2008 server is supported but you could give it a try. I've successfully stripped down XP with nLite to about 200MB with only the bare minimum I need for testing software. You might be able to do something similar to Windows 2008 with vLite.
My host is Vista 32b, and guest is
Windows2008 64b,
First mistake. Seriously, why not running 64 bit even on Vista? This would give your VM a good memory space to work with, while now even if it is possible with VmWare it goes through really nasty API's in the Windows layer.
That said, why use Vista as host? Why not directly load a 2008 R2 host, configure it into workstation mode (heck, you even get our friendly AERO if you install all the things the server leaves out per default) and be happy with it?
I guess it makes a difference to
disable all unnecessary services,
Hm, seriously? I run a couple of Hyper-V hosting servers on top of physical domain controllers without any reconfiguration and with good enough (i.e. great) perforamnce. Helps I dont ahve the typical workstation bottleneck (i.e. one overloaded hard disc). I never found a reason to disable any service for squeezing the last performance out.
Guest will run many java processes, a
DB and perform lots of file I/O
Well, get proper hardware for that. I.e. a hardware RAID controller, and a LOT of drives - in accordance with your needs. DB is IO sensitive. VERY sensitive.
This is not yet particularly programing related but, I am very interested in how Vista and XP resolve network names in a home LAN situation.
With Windows 2000, network name resolution was either done via the netbeui protocol - tcp/ip networks needes a wins server. XP and Vista no longer install netbeui by default, so its entirely unclear to me how PCs on a lan are meant to find each other.
One part of the puzzle's solution seems to be, IF there is a router appliance on the network that is configured as a DHCP server (and, as a result, a DNS server) then DNS queries of PC names tend to resolve.
In the more isolated case - a couple of XP and Vista PCs connected to an ethernet hub, configured to talk only tcp/ip - what services and what protocols are involved in name resolution and broadcasting?
It's been a while since I've had to deal with this sort of thing professionally, so I doubt I could give you an accurate off-the-cuff answer, but I'll say this: If you have access to a network similar to the one you are interested in, I highly recommend you install Wireshark or a similar tool on one of the machines involved and simply observe the traffic on the network in question. It's very easy to do and yields reliable information about a particular configuration very quickly, even when reality differs significantly from what one might reasonably expect. I've often been really surprised by some of the things I've seen, especially when it comes to name resolution.
Generating name lookup traffic is simplicity itself -- in fact, Wireshark itself might try to look up names in order to include them in its output, unless you ask it not to, so you might not need to take any explicit action at all, depending. Do remember to watch out for caches and switches.
Old question but for completion:
In peer networks (i.e. no Active Directory, WINS servers, etc.):
Windows Vista and above use Link-local Multicast Name Resolution(LLMNR), with fall back to NetBios over TCP/IP broadcast, which is what Windows XP uses.
It looks like Peer Name Resolution Protocol is being used with Vista and XP.
Peer Name Resolution Protocol
http://technet.microsoft.com/en-us/library/bb726971.aspx
People Near Me
http://technet.microsoft.com/en-us/library/bb726969.aspx
Edit: After doing a little bit more digging after Chris's comment, here is a link on how Windows XP Professional resolves names:
http://technet.microsoft.com/en-us/library/bb457118.aspx#ECAA
At work, I running Vista Business on a lavishly new PC, which runs great excepting two issues. In order of annoyance, but not importance:
When I reboot the machine, the Windows Splash is presented asking me to Press Ctrl + ALT + DELETE so I can logon. It takes three to five minutes and seceral key presses for me to be prompted to select my user account. After which, everything works like a charm.
As part of my duties with the firm, I am responsible for emergency work on a rotating basis and deploying patches during off-business hours. I have been given an older laptop with XPSP2 (downloading 3 for kicks right now) which I use for browsing with the intention of RDP to my desktop in the offices. If I am connected at the domain through conventional means, I am able to RDP. However, if I am using an existing broadbad connection with VPN, I am not able to get access. I am able to access other servers, desktops running a variety of OS'es including Vista.
So umm any ideas guys?
as for 2 - this happens with some proprietary VPN software (i.e. Cisco). My solution was to perform my work duties in a Virtual PC (which doesn't need its normal LAN abilities) and do my other network/internet tasks in the physical machine.
I have a Vista at work and uses my home PC to rdc in for support work. I do not experience your problem 1 so I cannot offer any advice. For your second problem have you tried the IP address instead of the machine name? We have situations where sometimes the dns resolution in the office network is not accurate.
Do you have remote access enabled, either on the machine, via group policy?
If not, you might have to go into the Control Panel\System and Maintenance\System and choose Remote Settings (from the menu on the left).
That will show you the options for Remote Deskop, including Don't allow connections, Allow connections from any version of Remote Desktop, and Allow connections from computers running Remote Desktop with Network Level Authentication (which might be the hang up you are experiencing over the VPN).
Good Luck.
I have to chalk this up to "something wierd with my laptop" as I was able to download RoyalTS and connect to the machine just fine. I had Remote connections permitted, firewall disabled, McAffee gone and others could access the machine.
The advice garnered above is excellent and useful for your typical rdp connections