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  • What does a DHCP-client consider to be the "best" answer?

    - by Nils
    We have training rooms where normally Windows XP is installed (via PXE). The "normal" DNS/DHCP infrastructure are Windows-Servers. The training room has its own VLAN (different from the Windows servers), so there is most propably an IP helper for DHCP requests active on the Cisco router where all PCs from that room are connected to. Now we wanted to convert some of the PCs to Linux instead. The idea was: Put our own Laptop with a DHCP server into the VLAN of the room and override the "normal" DHCP response. The idea was that this should work, since a directly attached DHCP server in that VLAN should have a faster response-time than the "normal" DHCP server located some hops away from that VLAN. It turned out that this did not work. We had to manually release the lease on the original DHCP server to get it working. On the Laptop we did see the client requesting the IP and "our" dhcp was sending NACKs to the Windows IP request, before that we did offer our own response. Old Question: Why did this not work out as expected? What is making the PC regain its old lease? Update 2012-08-08: The regain-issue has been explained in the DHCP-RFC. Now this explains why the PC regains its old lease. Now we do release the IP from the Windows-DHCP-server before giving it another try. Again - the Windows-DHCP-server wins. I suspect that there is some algorithm for the dhcp-client which determines the "best" dhcp-answer for the client. The new question is: How does the client choose the "best" answer?

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  • Unable to Access Certain Websites

    - by codejoust
    Through a local network, all computers except one ubuntu machine can access 1. Adobe.com 2. Icann.org 3. Apache.org 4. Example.com. The ubuntu machine returns (in firefox): "Though the site seems valid, the browser was unable to establish a connection." Furthermore, when I traceroute those websites using the ubuntu machine, they all return ubuntu.local, and it ends there: (traceroute to icann.org (192.0.32.7), 30 hops max, 40 byte packets 1 ubuntu.local (192.168.1.105) 3000.791 ms !H 3000.808 ms !H 3000.814 ms !H I've checked the hosts file, and there isn't anything in there, and I have an apache server there so if it was redirected to localhost, I'd probably see the localhost webroot page. Thanks in advance! user@ubuntu:~$ netstat -nr Kernel IP routing table Destination Gateway Genmask Flags MSS Window irtt Iface 169.254.0.0 0.0.0.0 255.255.0.0 U 0 0 0 eth1 192.0.0.0 0.0.0.0 255.0.0.0 U 0 0 0 eth1 0.0.0.0 192.168.1.1 0.0.0.0 UG 0 0 0 eth1 The Ubuntu Machine is one of six on the network. I'm using opendns for dns, so I do think that should be a problem.

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  • Troubleshooting loss of network connectivity in Windows 2003 - What else to check?

    - by Benny
    We are facing a weird problem in our data center. Our Backup server (running EMC Networker) loses network connection every alternate day around 3:00 AM (Backup schedule starts at midnight). After 2 hours of outage, the network connectivity recovers automatically and back to normal. What we observed: It is unlikely to be network issue, since it is directly connected to server farm switch (layer 2 connection without any intermediate hops). Further, the server is connected to two different switches for Load balancing using Broadcomm Teaming. a) If it were a switch related issue it is unlikely that both the network ports go down, since they are connected to different switch. b) A possibility Vlan wide issue is also ruled out since other devices in the same Vlan are fine. c) Switch interface status is always up. But there are lot of packet drops during the outage period - Can be attributed to high interface utilization of the backup server (near 100%) d) Connectivity is restored without any change on network. Next suspect is resource utilization on Windows server. Both CPU and Memory have rarely exceeded 80%, but NIC card utilization is alarmingly high (near 100%) Not really sure how to investigate this?

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  • Why can't I route to some sites from my MacBook Pro that I can see from my iPad? [closed]

    - by Robert Atkins
    I am on M1 Cable (residential) broadband in Singapore. I have an intermittent problem routing to some sites from my MacBook Pro—often Google-related sites (arduino.googlecode.com and ajax.googleapis.com right now, but sometimes even gmail.com.) This prevents StackExchange chat from working, for instance. Funny thing is, my iPad can route to those sites and they're on the same wireless network! I can ping the sites, but not traceroute to them which I find odd. That I can get through via the iPad implies the problem is with the MBP. In any case, calling M1 support is... not helpful. I get the same behaviour when I bypass the Airport Express entirely and plug the MBP directly into the cable modem. Can anybody explain a) how this is even possible and b) how to fix it? mella:~ ratkins$ ping ajax.googleapis.com PING googleapis.l.google.com (209.85.132.95): 56 data bytes 64 bytes from 209.85.132.95: icmp_seq=0 ttl=50 time=11.488 ms 64 bytes from 209.85.132.95: icmp_seq=1 ttl=53 time=13.012 ms 64 bytes from 209.85.132.95: icmp_seq=2 ttl=53 time=13.048 ms ^C --- googleapis.l.google.com ping statistics --- 3 packets transmitted, 3 packets received, 0.0% packet loss round-trip min/avg/max/stddev = 11.488/12.516/13.048/0.727 ms mella:~ ratkins$ traceroute ajax.googleapis.com traceroute to googleapis.l.google.com (209.85.132.95), 64 hops max, 52 byte packets traceroute: sendto: No route to host 1 traceroute: wrote googleapis.l.google.com 52 chars, ret=-1 *traceroute: sendto: No route to host traceroute: wrote googleapis.l.google.com 52 chars, ret=-1 ^C mella:~ ratkins$ The traceroute from the iPad goes (and I'm copying this by hand): 10.0.1.1 119.56.34.1 172.20.8.222 172.31.253.11 202.65.245.1 202.65.245.142 209.85.243.156 72.14.233.145 209.85.132.82 From the MBP, I can't traceroute to any of the IPs from 172.20.8.222 onwards. [For extra flavour, not being able to access the above appears to stop me logging in to Server Fault via OpenID and formatting the above traceroutes correctly. Anyone with sufficient rep here to do so, I'd be much obliged.]

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  • Change OpenVZ route to pass through ip failover

    - by Kevin Campion
    I have one dedicaced server with its own IP and another IP (failover) who refer to the first. I will wish to change the gateway of a Proxmox virtual machine (openvz) who runs on this dedicaced server to go through the failover IP rather than the ip of host main server. Once connected to a virtual machine, when I do a traceroute VE# traceroute www.google.fr traceroute to www.google.fr (209.85.229.104), 30 hops max, 60 byte packets 1 MY_SERVER_NAME.ovh.net (xxx.xxx.xxx.xxx FIRST_IP_MAIN_SERVER) 0.021 ms 0.010 ms 0.009 ms The first line tells me the ip of host main server. I would like that the traceroute display the second IP failover. VE# route Kernel IP routing table Destination Gateway Genmask Flags Metric Ref Use Iface 192.0.2.1 * 255.255.255.255 UH 0 0 0 venet0 default 192.0.2.1 0.0.0.0 UG 0 0 0 venet0 With iptables HOST# iptables -t nat -L Chain POSTROUTING (policy ACCEPT) target prot opt source destination MASQUERADE all -- anywhere anywhere MASQUERADE all -- anywhere anywhere SNAT tcp -- anywhere 10.10.101.2 tcp dpt:www state NEW,RELATED,ESTABLISHED,UNTRACKED to:SECOND_IP_FAILOVER SNAT all -- 10.10.101.2 anywhere to:SECOND_IP_FAILOVER 10.10.101.2 is the virtual machine IP (interface venet0) Any ideas ?

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  • How to block/avoid a particular IP when connecting to websites?

    - by Mark
    I'm having trouble connecting to a particular website. I can view it through a proxy, but not from home. So I ran a traceroute: Tracing route to fvringette.com [76.74.225.90] over a maximum of 30 hops: 1 <1 ms <1 ms <1 ms <snip> 2 * * * Request timed out. 3 9 ms 7 ms 27 ms rd2bb-ge2-0-0-22.vc.shawcable.net [64.59.146.226] 4 8 ms 7 ms 7 ms rc2bb-tge0-9-2-0.vc.shawcable.net [66.163.69.41] 5 10 ms 9 ms 9 ms rc2wh-tge0-0-1-0.vc.shawcable.net [66.163.69.65] 6 27 ms 23 ms 22 ms ge-gi0-2.pix.van.peer1.net [206.223.127.1] 7 18 ms 18 ms 20 ms 10ge.xe-0-2-0.van-spenc-dis-1.peer1.net [216.187.89.206] 8 9 ms 11 ms 10 ms 64.69.91.245 9 * * * Request timed out. 10 * * * Request timed out. ... Looks like this "64.69.91.245" is somehow blocking me. Can I tell my computer to avoid/bypass that IP when trying to connect?

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  • Is timeout in tracertoutput an indication of an error?

    - by nitramk
    TCP/IP packages sent from my computer to a remote server does not always reach destination and ends up being retransmitted sometimes several times before they succeed. To troubleshoot this, I'm running a tracert to the server: Tracing route to <site> [<address>] Over a maximum of 30 hops: 1 <1 ms <1 ms <1 ms mymachine 2 <1 ms <1 ms <1 ms gw.levonline.com [217.70.32.30] 3 <1 ms <1 ms <1 ms 81.201.213.218 4 <1 ms <1 ms <1 ms bmf1-hmf1.driften.net [81.201.213.12] 5 <1 ms <1 ms <1 ms 10ge-2-4-cr2.a1.sth.ownit.se [84.246.88.157] 6 <1 ms * <1 ms netnod-ix-ge-b-sth-4470.microsoft.com [195.69.11.181] 7 26 ms * * ge-3-0-0-0.ams-64cb-1a.ntwk.msn.net [207.46.42.1] 8 48 ms 57 ms 56 ms ten9-1.lts-76e-1.ntwk.msn.net [207.46.42.133] 9 * * * Request timed out. In step 6 and 7, I'm seeing timeouts while waiting for the reply from the server (as seen above). Running the same tracert many times gives varying output, sometimes the response is fine, but sometimes I get this timeout 1, 2 and sometimes for all 3 packets. The timeout always starts at the same server, netnod-ix-ge-b-sth-4470.microsoft.com. I've tried setting the tracert timeout to 10 seconds, but am still getting the timeout. Running tracert towards other servers does not give me the same timeout. Microsoft network technicians tells me that the problem is not on "their" side. Are these timeouts an indicator of a lost packet on the specific node which did not respond? Are the timeouts an indication of there being a problem, or is it normal?

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  • Private IP getting routed over Internet

    - by WernerCD
    We are setting up an internal program, on an internal server that uses the private 172.30.x.x subnet... when we ping the address 172.30.138.2, it routes across the internet: C:\>tracert 172.30.138.2 Tracing route to 172.30.138.2 over a maximum of 30 hops 1 6 ms 1 ms 1 ms xxxx.xxxxxxxxxxxxxxx.org [192.168.28.1] 2 * * * Request timed out. 3 12 ms 13 ms 9 ms xxxxxxxxxxx.xxxxxx.xx.xxx.xxxxxxx.net [68.85.xx.xx] 4 15 ms 11 ms 55 ms te-7-3-ar01.salisbury.md.bad.comcast.net [68.87.xx.xx] 5 13 ms 14 ms 18 ms xe-11-0-3-0-ar04.capitolhghts.md.bad.comcast.net [68.85.xx.xx] 6 19 ms 18 ms 14 ms te-1-0-0-4-cr01.denver.co.ibone.comcast.net [68.86.xx.xx] 7 28 ms 30 ms 30 ms pos-4-12-0-0-cr01.atlanta.ga.ibone.comcast.net [68.86.xx.xx] 8 30 ms 43 ms 30 ms 68.86.xx.xx 9 30 ms 29 ms 31 ms 172.30.138.2 Trace complete. This has a number of us confused. If we had a VPN setup, it wouldn't show up as being routed across the internet. If it hit an internet server, Private IP's (such as 192.168) shouldn't get routed. What would let a private IP address get routed across servers? would the fact that it's all comcast mean that they have their routers setup wrong?

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  • Is there any way for ME to improve routing to an overseas server? [migrated]

    - by Simon Hartcher
    I am trying to make a connection to a gaming server in Asia from Australia, but my ISP routes my connection through the US. Tracing route to worldoftanks-sea.com [116.51.25.54]over a maximum of 30 hops: 1 <1 ms <1 ms <1 ms 192.168.1.1 2 34 ms 42 ms 45 ms 10.20.21.123 3 40 ms 40 ms 43 ms 202.7.173.145 4 51 ms 42 ms 36 ms syd-sot-ken-crt1-ge-6-0-0.tpgi.com.au [202.7.171.121] 5 175 ms 200 ms 195 ms ge5-0-5d0.cir1.seattle7-wa.us.xo.net [216.156.100.37] 6 212 ms 228 ms 229 ms vb2002.rar3.sanjose-ca.us.xo.net [207.88.13.150] 7 205 ms 204 ms 206 ms 207.88.14.226.ptr.us.xo.net [207.88.14.226] 8 207 ms 215 ms 220 ms xe-0.equinix.snjsca04.us.bb.gin.ntt.net [206.223.116.12] 9 198 ms 201 ms 199 ms ae-7.r20.snjsca04.us.bb.gin.ntt.net [129.250.5.52] 10 396 ms 391 ms 395 ms as-6.r20.sngpsi02.sg.bb.gin.ntt.net [129.250.3.89] 11 383 ms 384 ms 383 ms ae-3.r02.sngpsi02.sg.bb.gin.ntt.net [129.250.4.178] 12 364 ms 381 ms 359 ms wotsg1-slave-54.worldoftanks.sg [116.51.25.54] Trace complete. Since I think it will be unlikely that my ISP will do anything, are there any ways to improve my routing to the server without them having to intervene? NB. The game runs predominately over UDP, so I believe most low ping services are out of the question, as they rely on TCP traffic.

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  • Connecting to same public IP from different locations yields different results

    - by DHall
    Since yesterday I've been unable to access one of my favorite time-wasting sites, boston.com. It starts to load but then it gets redirected to pagesinxt or something like that. After some investigation, I've narrowed it down to an issue with cache.boston.com, but only from my work location. I found the IP (216.38.160.107) , but even that doesn't work correctly from here at work. When I do a telnet 216.38.160.107 80 GET http://cache.boston.com/universal/css/hp_bgcom.css from another location, I get a nice long CSS, as expected. From here, I get an error (trimmed for size): HTTP/1.1 400 Bad Request Your request could not be processed. Request could not be handled This could be caused by a misconfiguration, or possibly a malformed request. For assistance, contact your network support team. Is there any way I can troubleshoot this further on my end? Tracert doesn't tell me anything too useful: Tracing route to vwrpx1.ttn.xpc-mii.net [216.38.160.107] over a maximum of 30 hops: 1 * * * Request timed out. Since it's not really work-related, I don't really want to bring it up to our network team unless I know what's going on, or if there's some risk to the network (ex. malware or something)

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  • How to prevent asymmetric routing with multiple eBGP routers?

    - by Andy Shinn
    I have 2 routers announcing a /22 subnet to different providers (one providers connects to each of the 2 routers). I have split the /22 in two /23 to announce one /23 on each of the routers plus the /22 (the providers will take the more specific route). This allows me to fail over and keep traffic inside the /23 in and out the same provider. What are other ways in which I could announce just the /22 with both routers and have packets from servers on the network behind the routers go back out the same router in which they came in from? EDIT: The main problem I come across, which end users and clients complain about the most, is that the least hop route is sometimes not the "optimal" route. In my case, I know that Provider B may have better latency to X nation. But when packets come in from provider B, they may go out Provider A or provider B. The reverse is also true. If I send a packet to X nation out provider A, even though it may have more hops back, the packet will likely come in from Provider B (which may have higher latency, packet loss, etc. to this nation)

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  • What's going on with traceroute?

    - by Kevin
    The following is what happens when I run traceroute from a certain location: # traceroute google.com traceroute to google.com (74.125.227.39), 30 hops max, 60 byte packets 1 gateway.local.enactpc.com (10.0.0.1) 0.138 ms 0.101 ms 0.084 ms 2 * * * 3 * * * 4 * * * 5 * * * 6 * * * 7 * * * 8 * * * 9 * * * 10 * * * 11 * * * 12 * * * 13 * * * 14 * * * 15 * * * 16 * * * 17 * * * 18 * * * 19 * * * 20 * * * 21 * * * 22 * * * 23 * * * 24 * * * 25 * * * 26 * * * 27 * * * 28 * * * 29 * * * 30 * * * Absolutely nothing of interest... Now, originally I thought this was just a fact of the location's network set up. (I assume they block pings or something...) However, watch what happens when I use nmap to run a traceroute... # nmap -sP --traceroute google.com Starting Nmap 5.21 ( http://nmap.org ) at 2012-09-25 22:18 CDT Nmap scan report for google.com (74.125.227.40) Host is up (0.034s latency). Hostname google.com resolves to 11 IPs. Only scanned 74.125.227.40 rDNS record for 74.125.227.40: dfw06s06-in-f8.1e100.net TRACEROUTE (using proto 1/icmp) HOP RTT ADDRESS 1 0.19 ms gateway.local.enactpc.com (10.0.0.1) 2 1.93 ms 99-20-92-1.lightspeed.austtx.sbcglobal.net (99.20.92.1) 3 25.61 ms 99-20-92-2.lightspeed.austtx.sbcglobal.net (99.20.92.2) 4 ... 6 7 23.68 ms 12.83.68.137 8 31.30 ms gar23.dlstx.ip.att.net (12.122.85.73) 9 ... 10 31.82 ms 72.14.233.65 11 32.27 ms 209.85.250.77 12 32.98 ms dfw06s06-in-f8.1e100.net (74.125.227.40) Nmap done: 1 IP address (1 host up) scanned in 3.29 seconds When using nmap I get A LOT more results than with traceroute, why? Note, I checked, and the difference in target IP addresses is not related...

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  • How can the route between two private IPs go via public IPs?

    - by Gilles
    I'm trying to understand what this output from traceroute means. I changed the IP addresses for privacy but retained the public/private IP range distinction. traceroute.db -e -n 10.1.1.9 traceroute to (10.1.1.9), 30 hops max, 60 byte packets 1 10.0.0.1 0.596 ms 0.588 ms 0.577 ms 2 10.0.0.2 1.032 ms 1.029 ms 1.084 ms 3 10.0.0.3 3.360 ms 3.355 ms 3.338 ms 4 23.0.0.4 3.974 ms 4.592 ms 4.584 ms 5 23.0.0.5 13.442 ms 13.445 ms 13.434 ms 6 45.0.0.6 13.195 ms 12.924 ms 12.913 ms 7 67.0.0.7 52.088 ms 51.683 ms 52.040 ms 8 10.1.1.8 46.878 ms 44.575 ms 44.815 ms 9 10.1.1.9 45.932 ms 45.603 ms 45.593 ms The first 10.0.* range is inside my organisation. The last 10.1.* range is another site of my organisation. The intermediate addresses belong to various ISPs. I expect that there is some kind of VPN between the two sites, but I don't know much about our network topology. What I don't understand is how the route can go from a private address through public addresses back into private addresses. Searching led me to Public IPs on MPLS Traceroute, which gives a possible explanation: MPLS. Is MPLS the only possible or most likely explanation? Otherwise what does this tell me about our network infrastructure? Bonus question for my edification: in this scenario, who is generating the ICMP TTL exceeded packets and if relevant mangling their source and destination addresses?

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  • How to set a static route for an external IP address

    - by HorusKol
    Further to my earlier question about bridging different subnets - I now need to route requests for one particular IP address differently to all other traffic. I have the following routing in my iptables on our router: # Allow established connections, and those !not! coming from the public interface # eth0 = public interface # eth1 = private interface #1 (10.1.1.0/24) # eth2 = private interface #2 (129.2.2.0/25) iptables -A INPUT -m state --state ESTABLISHED,RELATED -j ACCEPT iptables -A INPUT -m state --state NEW ! -i eth0 -j ACCEPT iptables -A FORWARD -i eth0 -o eth1 -m state --state ESTABLISHED,RELATED -j ACCEPT iptables -A FORWARD -i eth0 -o eth2 -m state --state ESTABLISHED,RELATED -j ACCEPT # Allow outgoing connections from the private interfaces iptables -A FORWARD -i eth1 -o eth0 -j ACCEPT iptables -A FORWARD -i eth2 -o eth0 -j ACCEPT # Allow the two private connections to talk to each other iptables -A FORWARD -i eth1 -o eth2 -j ACCEPT iptables -A FORWARD -i eth2 -o eth1 -j ACCEPT # Masquerade (NAT) iptables -t nat -A POSTROUTING -o eth0 -j MASQUERADE # Don't forward any other traffic from the public to the private iptables -A FORWARD -i eth0 -o eth1 -j REJECT iptables -A FORWARD -i eth0 -o eth2 -j REJECT This configuration means that users will be forwarded through a modem/router with a public address - this is all well and good for most purposes, and in the main it doesn't matter that all computers are hidden behind the one public IP. However, some users need to be able to access a proxy at 192.111.222.111:8080 - and the proxy needs to identify this traffic as coming through a gateway at 129.2.2.126 - it won't respond otherwise. I tried adding a static route on our local gateway with: route add -host 192.111.222.111 gw 129.2.2.126 dev eth2 I can successfully ping 192.111.222.111 from the router. When I trace the route, it lists the 129.2.2.126 gateway, but I just get * on each of the following hops (I think this makes sense since this is just a web-proxy and requires authentication). When I try to ping this address from a host on the 129.2.2.0/25 network it fails. Should I do this in the iptables chain instead? How would I configure this routing?

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  • Measure Upload Speed between a client and our server

    - by tresstylez
    We host a SAAS application specially customized for multiple clients. For one customer in particular -- they are reporting sporadic performance issues from various locations on their network, in particular UPLOADING documents through a form on our website. The client claims they have "bandwidth to spare" and that utilization of their "pipe" is so low that it MUST be our application, but our application has MANY clients and all features are working fine for all other clients. Interestingly enough -- DOWNLOADS (ie. just accessing the website, or downloading documents) is working fine. Speed test shows that they should get 1.2Mbps UP. So, a 3MB file should take 20 secs to upload. It takes 60+ seconds on their network. Sometimes even small files take OVER 10 minutes to upload or they timeout. Pings and Traceroutes don't show any abnormally long hops or response times. They claim other SAAS applications they use allow them to upload just fine. Both IT teams are working together to resolve this issue. What kind of data can I request from the clients to begin ruling things out. Seems like we need to somehow measure LATENCY of the networks involved or even at the switch level, we need to understand if packets are getting dropped somewhere and why. Where should I start? Any help is appreciated. I'll provide more info upon requests

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  • Ping with explicit next-hop selection (aka Monitoring multiple default gateways)

    - by Michuelnik
    I have a linux (debian) router with two internet connections (A) and (B). (A) is preferred, (B) is fallback. I want to monitor the internet connection (and not only the availability of the gateways!) and change the default route appropriately. If (A) is not providing internet, switch to (B) If (A) is providing internet again, switch back to (A). Only problem I have is in case (2). My routing table points towards a working internet so I cannot easily detect whether internet is working over link (A) again. I am search for a ping or traceroute (or other diagnosis-tool) which can select the next-hop explicitly. ping -r looks promising, but can only ping a host on the lan. (It only has to write another destination address in the packet, damnit!) traceroute -g gateway looks even more promising and nearly does what I want - but sets source routing options which my next-hops deny. (Not within my administrative boundary...) I just want a $ping, that can: select a source interface (and address) select a next-hop on that interface ping any arbitrary ip address I could do evil trickery with policy-based routing but that would have production impact for all users. I would like to see a side-effect-free solution....

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  • Managed LAMP platform for maximizing availability and global reach, not scalability

    - by user66819
    Assume a Linux/Apache/MySQL/PHP application for a small base of registered users. With small userbase, there are no traffic peaks so the scalability that cloud platforms offer is not imperative. But the system is mission-critical, so availability is the primary goal. Users are also distributed across Asia, Europe, and US, so multiple server locations that minimize users' network hops would be highly desirable. The dream: a managed VPS platform where we would configure a single server (uploading PHP and other files, manipulating database, etc.), and the platform would automatically mirror the server in a handful of key places around the world (say one on each US coast, one in Europe, one in east Asia). File system synchronization and MySQL replication would happen automatically. Core operating system is managed, so we don't need to do full system administration and security, and low-level backups are also done by service provider, though we also do our own backups as well. Couple this with some sort of DNS geo-detection, so users are routed to the nearest operational server... with support for https, of course. Does such a dream exist? If not, what are some approaches to accomplish the same end with minimal time investment and minimal monthly hosting costs?

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  • What can be done to improve time synchronization on networks with sporadic internet access?

    - by anregen
    I'm looking for advice setting up time servers for a very non-typical network. I support many closed networks that have occasional access to the internet. A network would get access most days for a few hours, but would frequently go 1-3 weeks blacked-out. The computers/servers on this network are mostly *nix-based, but not all the same flavor. The entire network is mobile, so when it connects, it will have very different hops/latency to internet time servers. The servers on the closed network are powered-off frequently (at least daily). Right now, my gut tells me to use NTP (because I hate re-learning all the stuff that someone else already got working pretty well). But I have several issues, and am looking for someone with experience in this type of strange situation. I currently have no solution in place, I'm simply letting the internal clocks drift. This results in errors of ~600s in a majority of networks. I have seen mismatch worse than 10,000s. Is there something "better" than NTP in this situation? I know NTP likes to have very frequent, consistent access to servers that give nearly identical answers. I won't have that. How many internal NTP servers should I configure, so that during periods of internet blackout, I have internal time that is consistent within the closed network? There is no human access. No matter how large the mismatch, the server(s) must attempt to correct itself. Discrete steps are very bad. No matter how large the mismatch, the correction must be "slewed", not "stepped". I understand that this could take many hours to correct.

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  • Can't reach only certain websites from my Wifi (with macbook and iphone)

    - by mellin
    I can't access certain websites neither from my macbook nor from my iphone when connected to my Wifi. The same website can be opened from another windows computer connected to the same Wifi. This is what happens when I try to ping it: PING ilpost.it (151.1.175.113): 56 data bytes Request timeout for icmp_seq 0 Request timeout for icmp_seq 1 Request timeout for icmp_seq 2 ... And when I try to traceroute it: host-001:~ j$ traceroute www.ilpost.it traceroute to ilpost.it (151.1.175.113), 64 hops max, 52 byte packets 1 vodafonedslrouter (192.168.1.1) 2.965 ms 0.743 ms 0.745 ms 2 * 2.96.54.77.rev.vodafone.pt (77.54.96.2) 12.076 ms 10.871 ms 3 77.41.30.213.rev.vodafone.pt (213.30.41.77) 14.145 ms 10.693 ms 11.960 ms 4 85.205.11.49 (85.205.11.49) 9.658 ms 8.946 ms 9.085 ms 5 85.205.13.105 (85.205.13.105) 57.497 ms 57.621 ms 48.080 ms 6 188.111.129.17 (188.111.129.17) 49.483 ms 51.338 ms 48.852 ms 7 85.205.25.174 (85.205.25.174) 47.891 ms 49.219 ms 47.821 ms 8 * * * 9 * * * 10 * * * 11 * * * I've flushed my DNS cache but nothing changed. This is quite dramatic as it seems to depend on 85.205.25.174 hop and don't know how to avoid it. Any suggestions? I add that 3 days ago everything worked fine. Then it has stopped.

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  • Can't reach only certain websites from my Wifi (with macbook and iphone)

    - by trampj
    I can't access certain websites neither from my macbook nor from my iphone when connected to my Wifi. The same website can be opened from another windows computer connected to the same Wifi. This is what happens when I try to ping it: PING ilpost.it (151.1.175.113): 56 data bytes Request timeout for icmp_seq 0 Request timeout for icmp_seq 1 Request timeout for icmp_seq 2 ... And when I try to traceroute it: host-001:~ j$ traceroute www.ilpost.it traceroute to ilpost.it (151.1.175.113), 64 hops max, 52 byte packets 1 vodafonedslrouter (192.168.1.1) 2.965 ms 0.743 ms 0.745 ms 2 * 2.96.54.77.rev.vodafone.pt (77.54.96.2) 12.076 ms 10.871 ms 3 77.41.30.213.rev.vodafone.pt (213.30.41.77) 14.145 ms 10.693 ms 11.960 ms 4 85.205.11.49 (85.205.11.49) 9.658 ms 8.946 ms 9.085 ms 5 85.205.13.105 (85.205.13.105) 57.497 ms 57.621 ms 48.080 ms 6 188.111.129.17 (188.111.129.17) 49.483 ms 51.338 ms 48.852 ms 7 85.205.25.174 (85.205.25.174) 47.891 ms 49.219 ms 47.821 ms 8 * * * 9 * * * 10 * * * 11 * * * I've flushed my DNS cache but nothing changed. This is quite dramatic as it seems to depend on 85.205.25.174 hop and don't know how to avoid it. Any suggestions? I add that 3 days ago everything worked fine. Then it has stopped.

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  • Need WIF Training?

    - by Your DisplayName here!
    I spend numerous hours every month answering questions about WIF and identity in general. This made me realize that this is still quite a complicated topic once you go beyond the standard fedutil stuff. My good friend Brock and I put together a two day training course about WIF that covers everything we think is important. The course includes extensive lab material where you take standard application and apply all kinds of claims and federation techniques and technologies like WS-Federation, WS-Trust, session management, delegation, home realm discovery, multiple identity providers, Access Control Service, REST, SWT and OAuth. The lab also includes the latest version of the thinktecture identityserver and you will learn how to use and customize it. If you are looking for an open enrollment style of training, have a look here. Or contact me directly! The course outline looks as follows: Day 1 Intro to Claims-based Identity & the Windows Identity Foundation WIF introduces important concepts like conversion of security tokens and credentials to claims, claims transformation and claims-based authorization. In this module you will learn the basics of the WIF programming model and how WIF integrates into existing .NET code. Externalizing Authentication for Web Applications WIF includes support for the WS-Federation protocol. This protocol allows separating business and authentication logic into separate (distributed) applications. The authentication part is called identity provider or in more general terms - a security token service. This module looks at this scenario both from an application and identity provider point of view and walks you through the necessary concepts to centralize application login logic both using a standard product like Active Directory Federation Services as well as a custom token service using WIF’s API support. Externalizing Authentication for SOAP Services One big benefit of WIF is that it unifies the security programming model for ASP.NET and WCF. In the spirit of the preceding modules, we will have a look at how WIF integrates into the (SOAP) web service world. You will learn how to separate authentication into a separate service using the WS-Trust protocol and how WIF can simplify the WCF security model and extensibility API. Day 2 Advanced Topics:  Security Token Service Architecture, Delegation and Federation The preceding modules covered the 80/20 cases of WIF in combination with ASP.NET and WCF. In many scenarios this is just the tip of the iceberg. Especially when two business partners decide to federate, you usually have to deal with multiple token services and their implications in application design. Identity delegation is a feature that allows transporting the client identity over a chain of service invocations to make authorization decisions over multiple hops. In addition you will learn about the principal architecture of a STS, how to customize the one that comes with this training course, as well as how to build your own. Outsourcing Authentication:  Windows Azure & the Azure AppFabric Access Control Service Microsoft provides a multi-tenant security token service as part of the Azure platform cloud offering. This is an interesting product because it allows to outsource vital infrastructure services to a managed environment that guarantees uptime and scalability. Another advantage of the Access Control Service is, that it allows easy integration of both the “enterprise” protocols like WS-* as well as “web identities” like LiveID, Google or Facebook into your applications. ACS acts as a protocol bridge in this case where the application developer doesn’t need to implement all these protocols, but simply uses a service to make it happen. Claims & Federation for the Web and Mobile World Also the web & mobile world moves to a token and claims-based model. While the mechanics are almost identical, other protocols and token types are used to achieve better HTTP (REST) and JavaScript integration for in-browser applications and small footprint devices. Also patterns like how to allow third party applications to work with your data without having to disclose your credentials are important concepts in these application types. The nice thing about WIF and its powerful base APIs and abstractions is that it can shield application logic from these details while you can focus on implementing the actual application. HTH

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  • Creating a shim Stream

    - by spender
    A decompression API that I am using has the following API: Decode(Stream inStream,Stream outStream) I'd like to create a wrapper around this API, such that I can create my own Stream class which offers up the decoded data. Stream decodedStream=new BlaDecodeStream(inStream); So that I can than use this stream as a parameter to the XmlReader constructor in the same way one might use the System.IO.Compression.GZipStream. As far as I can tell, the only other option is set outStream stream to a MemoryStream or to a FileStream and go in two hops. The files I am dealing with are enormous, so neither of these options are particularly attractive. Before I go reinventing the wheel, is there any prior art that I might be able to draw from, or something in the BCL I might have missed? The CircularStream implementation here would go some of the way to helping, but I'm really looking for something similar that would block (as opposed to over/underrun) when the Stream's internal buffer is 'empty' when reading from it and block when the internal buffer is full when writing to it. In this way it could serve as parameter outStream and simultaneously (i.e. from another thread) could be read from by the XmlReader.

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  • Prefuse: Reloading of XML files

    - by John
    Hello all, I am a new to the prefuse visualization toolkit and have a couple of general questions. For my purpose, I would like to perform an initial visualization using prefuse (graphview / graphml). Once rendered, upon a user click of a node, I would like to completely reload a new xml file for a new visualization. I want to do this in order to allow me to "pre-package" graphs for display. For example. If I search for Ted. I would like to have an xml file relating to Ted load and render a display. Now in the display I see that Ted has nodes associated called Bill and Joe. When I click Joe, I would like to clear the display and load an xml file associated with Joe. And so on. I have looked into loading one very large xml file containing all node and node relationship info and allowing prefuse to handle this using the hops from one level to another. However, eventually I am sure that system performance issues will arise due to the size of data. Thanks in advance for any help, John

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  • Are Large iPhone Ping Times Indicative of Application Latency?

    - by yar
    I am contemplating creating a realtime app where an iPod Touch/iPhone/iPad talks to a server-side component (which produces MIDI, and sends it onward within the host). When I ping my iPod Touch on Wifi I get huge latency (and a enormous variance, too): 64 bytes from 192.168.1.3: icmp_seq=9 ttl=64 time=38.616 ms 64 bytes from 192.168.1.3: icmp_seq=10 ttl=64 time=61.795 ms 64 bytes from 192.168.1.3: icmp_seq=11 ttl=64 time=85.162 ms 64 bytes from 192.168.1.3: icmp_seq=12 ttl=64 time=109.956 ms 64 bytes from 192.168.1.3: icmp_seq=13 ttl=64 time=31.452 ms 64 bytes from 192.168.1.3: icmp_seq=14 ttl=64 time=55.187 ms 64 bytes from 192.168.1.3: icmp_seq=15 ttl=64 time=78.531 ms 64 bytes from 192.168.1.3: icmp_seq=16 ttl=64 time=102.342 ms 64 bytes from 192.168.1.3: icmp_seq=17 ttl=64 time=25.249 ms Even if this is double what the iPhone-Host or Host-iPhone time would be, 15ms+ is too long for the app I'm considering. Is there any faster way around this (e.g., USB cable)? If not, would building the app on Android offer any other options? Traceroute reports more workable times: traceroute to 192.168.1.3 (192.168.1.3), 64 hops max, 52 byte packets 1 192.168.1.3 (192.168.1.3) 4.662 ms 3.182 ms 3.034 ms can anyone decipher this difference between ping and traceroute for me, and what they might mean for an application that needs to talk to (and from) a host?

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  • Online voice chat: Why client-server model vs. peer-to-peer model?

    - by sstallings
    I am adding online voice chat to a Silverlight app. I've been reviewing current apps, services and SDKs found thru online searches and forums. I'm finding that the majority of these implement a client-server (C/S) model and I'm trying to understand why that model versus a peer-to-peer (PTP) model. To me PTP would be preferable because going direct between peers would be more efficient (fewer IP hops and no processing along the way by a server computer) and no need for a server and its costs and dependencies. I found some products offer the ability to switch from PTP to C/S if the PTP proves insufficient. As I thought more about it, I could see that C/S could be better if there are more than two peers involved in a conversation, then the server (supposedly with more bandwidth) could do a better job of relaying each peers outgoing traffic to the multiple other peers. In C/S many-to-many voice chatting, each peer's upstream broadband (which is where the bottleneck inherently is) would only have to carry each item of voice traffic once, then the server would use its superior bandwidth to relay the message to the multiple other peers. But, in a situation with one-on-one voice chatting it seems that PTP would be best. A server would not reduce each of the two peer's bandwidth requirements and would only add unnecessary overhead, dependency and cost. In one-on-one voice chatting: Am I mistaken on anything above? Would peer-to-peer be best? Would a server provide anything of value that could not be provided by a client-only program? Is there anything else that I should be taking into consideration? And lastly, can you recommend any Silverlight PTP or C/S voice chat products? Thanks in advance for any info.

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