Networking :: Can Ping But Can't Wget / Strange Network Behavior
Apr 28, 2011
I have a small ARM machine running an Arch linux variant, PlugApps. It was set up and working fine at my home, with a standard networking setup -- cable modem and router. I could do pretty much anything I needed to access the net fine.This machine is a remote monitoring system for another location. I shipped it to that location and am now trying to get it set up using another set of hands on site. There it is on the network behind a dsl modem and a router. I forwarded ports from the dsl modem to the router and from the router to the ARM computer.
In both cases the ARM machine is/was configured to use dhcp.So here's the deal:I can ssh into the ARM machine just fine.I can ping hosts on the wan fine (eg: stanford.edu).BUT:wget fails for not being able to resolve a valid address (eg: http://checkip.dyndns.org)the PlugApps package management system (pacman) cannot resolve the repository address the openntp time sync isn't working On the new network, I am able to connect to another client windows PC which has the same associated network info (Bcast address, Mask, etc. - comparing windows "ipconfig" vs linux "ifconfig" outputs) but which can resolve addresses for web browsing, etc.What am I missing? If it can resolve addresses for pings, why can't it work for other address requests? If I can ssh interact with it, why can't it connect to the net for other purposes?
I have an old PC running an older version of linux with two network cards serving as my firewall router. The network cards are netgear 310tx cards. Noticed traffic was not getting routed at times. Figured my switch was going bad, so I hooked up an old hub to keep keys systems communicating while I get a new switch. No problems with hub, but only has 5 ports.
Get new switch (different make/model from old one), install, a couple of my systems have connectivity problems, but others do not. Thinking it was a bad switch, returned it, got a new one just like my old one (which I thought was going bad, but worked for several years). Hook it up, paying attention to my firewall console and notice martian header messages. Network traffic not getting routed at all. The interface for connected to LAN was slow to get started (my firewall can communicate to the Internet, but LAN communication was hosed).
System would "hang" spitting out martian header messages until I disconnected LAN cable. Thinking network card may be bad, replaced it with another version of the same type. Same problems: martian header messages and traffic not getting routed.
HOWEVER, if I remove the switch and use my old hub, no problems. Networking appears to work for all systems connected to hub. Since I and my wife work from home, I'm using the hub right now (with non-essential systems not connected due to limited ports). I can only do any real experimentation at night.
I have no idea why things would work differently between using a hub vs a switch. Could something have gone awry with the linux kernel (2.4.20-46.7)?
I've been trying to use MySQL in Ubuntu but I've been having some connection issues and in trying to troubleshoot that, I observed this strange behavior with pings in Ubuntu Desktops inside our network.
- All Ubuntu Servers we have (10.10 and 8.04) behave as expected - All Windows machines behave as expected - All 5 Ubuntu Desktops we have, (10.10 and 9.10) exhibit the following unexpected behavior:
If they have a local ip addresses and are connected within the internal network, either to a switch or directly to a router, pings take much longer to be sent. It's not a higher lag, it's the time between each ping that increases. I have to wait for around 5 seconds for each ping, but the time in the ping reply is less than 100ms, also they're all in order so I assume it's the system delaying the sending of each ping.
If I plug a USB 3G modem directly then it works as expected again (~1 sec between each ping sent). Is this an intended feature, that depends on the network environment, or is this something I should look into more closely?
For some reason some command line commands are unable to resolve urls, whereas other commands work as they should. I have checked most setting but am unable to find out what is wrong and am no closer to figuring out what and why.
[root@subzero ~]# yum update Loaded plugins: refresh-packagekit [URL]: [Errno 4] IOError: <urlopen error (-2, 'Name or service not known')> Trying other mirror. Error: Cannot retrieve repository metadata (repomd.xml) for repository: atrpms. Please verify its path and try again [root@subzero ~]# .....
I have recently upgraded to 11.4 and also had to renew an AP (HP ProCurve 10ag). This was several years old but replaced an identical model which had been working well until recently. I thought it would be appropriate to flash newer firmware as the device four releases behind the times. The access point serves partner's XP laptop and my openSUSE 11.4 laptop and after flashing the firmware both machines would make a connection and then break and remake, to the extent that the openSUSE machine became unusable. I thought it was an encryption problem and spent hours changing the AP and Client setups to no avail
After reading a thread here I checked out dmesg and this is what I found:- [78.639247] wlan0: authenticate with 00:1d:b3:4b:ae:14 (try 1) [78.640804] wlan0: authenticated [78.642507] wlan0: associate with 00:1d:b3:4b:ae:14 (try 1) [78.651195] wlan0: RX AssocResp from 00:1d:b3:4b:ae:14 (capab=0x411 status=0 aid=1) [78.651200] wlan0: associated [78.652222] ADDRCONF(NETDEV_CHANGE): wlan0: link becomes ready [78.652283] cfg80211: Calling CRDA for country: DE [78.674378] cfg80211: Regulatory domain changed to country: DE ..... This went on and on.
I am using an virtual machine. where I need to ping from one machine to another. earlier I was able to ping. But after going to google.com once, I cannot ping back to this machine.
But if I gave ping -I eth1 <IP> then I can ping.
I cannot install any package, so tell me solution which includes not installing any package.
This applies to my 2 opensuse PC's, my Windows PC is fine.I can ping a hostname, say "PC1" but I can not ping PC1.domain.local (even the host PC can not ping it's own FQDN). When I ping just the hostname the ping stats even list the FQDN.Onto the next issue, since all my PC's, have the domain prefix domain.local, my Synology can not. I can ping it's IP and that is it. I can resolve it's name with nmblookup just fine tho and that is what is killing me. How is this not resolving.Even weirder, I can browse to "Synology" in Network Servers under places on the slab.
I can ping the router, but I cannot ping anything outside of the network. The ping just sits there and eventually times out, no error message. I cannot download updates and it is the only box inside the network having any issues accessing the internet. I am running 10.10 server. I can get a list of packages on the update server, but not download them, it appears to be in an incoming issue. I'm using a motorola Netopia router in bridge mode with a netgear SRXN3205 as a router. Again every other system can download fine. I have tried running on one nic, no help dhcp, static again does nothing. I can pulls host [URL].. and I get
[code]...
It may be worth noting that I set the box up at home on a dlink router and it worked fine, however I am confused why it is the only system on the network having these issues every other box can ping just fine.
I am a new user to Linux but in the last couple of months gained some Idea about it,I am trying to set up a small network in my office having 3 windows xp PCs, two fedora10 PCsI have an adsl router with 4-port hub connecting to the internet, one switch (say sw1) and one linux PC (say linux1) is connected directly to the router, the three win xp PCs are connected to switch sw1.all the above is working fine, I am able to get connected to Internet In all the systems, and able to network among all the above four.Now I want to make the linux1 as a proxy server for, hence I added another network card into it connected it to another switch sw2, which is connected to another linux pc (say linux2).
I have tried a hundred things, and googled an equal no. and finally posting it here.In order to reduce confusion I have disabled DHCP in all machines, and given static ips insteadNetworkManager was not happy about it, hence to fix my static IP i disabled NetworkManager ('chkconfig NetworkManager off')
I have a somewhat complicated network setup that I am testing on an internal network. I have the following route setup:
PC Client (192.168.2.100) --> Router (192.168.2.1) --> DSLAM (on our internal network) --> PPPOE Server (192.168.9.1) on Linux Ubuntu 8.04 on interface card eth2.
On the same Linux Ubuntu Machine on interface card eth1 (static IP 192.168.5.100), I have an Asterisk SIP server plugged into it. SIP Server = 192.168.5.101 (static) I need the PC client (192.168.2.100) to register via SIP soft phone to register on the SIP server (192.168.5.101). From the PC client I can ping as far as the eth1 interface (192.168.5.100)...but cannot ping the SIP Server (.101).
From the SIP server (192.156.5.101)...I can ping 192.168.5.100, I can ping 169.254.5.228 (Eth2:avahi), but not sure what that is. I cannot ping the pppoe default gateway (192.168.9.1), which I think you cannot anyway. No firewalls are running. My IPtables I cleaned out totally. I think it might be as simple as a route add, but I really have no clue. Tried building a virtual bridge using brctl LINUX betweeh eth1 and eth2, but that made things worse (could not ping anything after that)
I have ubuntu 10.4 running on both my desktop and laptop. Both machines are connected to the router in wireless mode with Wifi.I can access internet from both machines without any issues, however I cant ping one machine from another. (and vice versa)
I have two linux servers, I tried to ping from one linux box to another and vice versa but error message is "connect: Network is unreachable" Where as If I tried from windows machine I am getting the reply from both the servers. C:Documents and Settings>ping bnkprod
Pinging bnkprod.softtech.com [172.20.40.141] with 32 bytes of data: Reply from 172.20.40.141: bytes=32 time=16ms TTL=64 Reply from 172.20.40.141: bytes=32 time<1ms TTL=64 Reply from 172.20.40.141: bytes=32 time<1ms TTL=64 Reply from 172.20.40.141: bytes=32 time<1ms TTL=64
Ping statistics for 172.20.40.141: Packets: Sent = 4, Received = 4, Lost = 0 (0% loss), Approximate round trip times in milli-seconds: Minimum = 0ms, Maximum = 16ms, Average = 4ms
So in an effort to increase the speed of my netbook, I removed Ubuntu and installed Lubuntu on it. When I tried to mount my samba share as I normally do, I noticed it wasn't able to connect - mount error(113): No route to host. Sensing something fishy, I attempted to ping the machine (both by name and by IP) - Destination Host Unreachable.The machine I'm trying to connect to is using Ubuntu 10.04 x64. I attempted to ping the other way and it was able to connect to the netbook just fine. When the netbook was using Ubuntu, it was connecting fine. My iptables check out ok, but here is the output of iptables -nvL:
Does lubuntu have some funky firewall built in to it that I can't find? (I've Googled for information on a Lubuntu default firewall and can't find any)
I'm having trouble pinging localhost, specifically, pinging localhost when I'm not connected to a network. When I try it keeps telling me the operation is not permitted:
Code:
matt@mubuntu:~$ ping localhost PING localhost (127.0.0.1) 56(84) bytes of data. ping: sendmsg: Operation not permitted ping: sendmsg: Operation not permitted
if I connect to the network, start pinging then disconnect it continues pinging. Google seems to think it could be something to do with my iptables setup:
matt@mubuntu:~$ route -n Kernel IP routing table Destination Gateway Genmask Flags Metric Ref Use Iface 127.0.0.0 0.0.0.0 255.0.0.0 U 0 0 0 lo
But as far as I can tell there isn't anything in there which would stop me connecting to the localhost (I also can't connect to my local apache instance when offline)... (It's worth mentioning that a couple of weeks ago I had the pc setup to share it's internet connection with a laptop, ala this guide, however I've since disabled the iptables rules and disabled ip forwarding.)
i have installed linux debian in my computer but i have aproblem , i have a ping only on my computer itself , not to gateway or other computers on my network .
Ip : 10.0.88.9 Gateway : 10.0.88.1 dns :10.0.88.7
note:when i have installed system i have no internet connection so it is not installed updates
I have installed Micro Core onto a usb of mine and am running it on my laptop. I have been able to successfully obtain a connection and valid ip with my router. As you can see below my wireless connection seems valid computer-end and on my router's page it comes under the list of attached devices.Although this is all fine and dandy, I'm am unable to ping my router or any other computer on my network, I am also unable to ping my laptop from other computers on the network. Also by the looks of it I have having no trouble transmitting, but I am not receiving any packets.
I run a server that is connected to several other boxes in a private network (192.168.0.0). I have had no problems previously, but upon a reinstall of Debian squeeze I have no connectivity to the private network: a ping of other addresses on that network fail. Ping and connection to outside world is fine. This box is configured similarly to another on this private network which connects successfully. I have quadruple-checked all my basic information. I post my ifconfig below of the malfunctioning device, then the ifconfig for equivalent nic on a box connected succesfully to the private network.
Questions:
1.Could it be a cable problem? (I don't see how since the cables have not been changed I do not believe since my reinstallation).
2. What about the difference in the last lines of eth1 below and eth2 of the successful box. Is it significant that the bad eth1 reads Memory:fc3a0000-fc3c0000
I had configured Squid in RHEL 5 and facing an issue with pinging. Not able to ping any website,hostname is resolving to ip address but not able to ping
I want to ssh to a pc in our home network. It is a standard network in terms of a DSL router, dynamic IPs via DHCP, WPA2/PSK security, wireless network connection for all pcs except one which is wired to the router.I got the error "no route to host" from ssh. Openssh-server was already installed. It turned out later that the laptop I want to ssh to (namely the one which is connected by cable) cannot be pinged by any other laptop on the network.
The pc in question (lucid lynx with most recent updates) is online, can ping itself and the router, but cannot ping others in the network and cannot be pinged by them. I suspect a firewall setting of being the problem.
Been helping a user who recently upgraded to 11.04 as his networking stopped after the upgrade. One thing I noticed was that he could not get ping to work.Then checked my 11.04 machine and it also fails to ping using Network Tools. I know the network is OK as I am using my Ubuntu machine to write this. Ping from the command line is fine so it is only the Network Tools ping test that appears to be broken.
Asked another Ubuntu 11 user to check his machine and he also cannot get ping to work even though his machine appears to be fine. Again this is only using the GUI tool.I know it is not hardware as I can dual boot and in XP everything is fine and I can ping all my systems. Also I am sharing a folder from my Ubuntu and my Mac shares the folder just fine. The Mac can also ping everything except the Ubuntu box. Command line ping works so it is not a basic network problem.So as far as I can tell the Network Tools ping test is not working. Has anyone else seen this or can confirm that it is broke. How do I report this or get it fixed?
I am trying to ping my Windows machine connected to an open network (I'm at a internet caf) from my linux VM (also connected to the same network with a usb adapter), but I'm obtaining this output:
# ping 10.23.47.12 PING 10.23.47.12 (10.23.47.12) 56(84) bytes of data. From 10.128.128.1 icmp_seq=1 Packet filtered From 10.128.128.1 icmp_seq=2 Packet filtered
With high probability host 10.128.128.1 is a firewall or some router with packet filtering mechanism; but I don't understand how it can be possible to implement this kind of solution, with what kind of software or hardware? I also tried a nmap scan to my Windows machine but it returns me scan results from another host(the firewall or the router I suppose):
nmap -sS -O -P0 10.23.47.12 Starting Nmap 5.51 ( http://nmap.org ) at 2011-07-09 15:46 CDT Nmap scan report for 10.23.47.12 Host is up (0.097s latency). All 1000 scanned ports on 10.23.47.12 are filtered
[Code]...
So my questions is, how is technically possible to implement this kind of restriction within hosts connected on the same network? It's the first time I see this kind of configuration.
I have OpenVPN running successfully on a CentOS Linux server. All remote clients connect without a problem and can ping the server LAN (10.5.0.0/24) . The server address is 10.5.0.1. All network shares on the server are available to the remote clients via SAMBA shares and this works well.The problem is that I am unable to get the remote clients to access services on the LAN clients. For example, there is a webserver running on a Windows XP PC (on the server LAN @ 10.5.0.2) with no firewall enabled. The remote VPN clients can ping this webserver at 10.5.0.2, but cannot browse the webserver at [URL]. All clients on the server LAN can however browse the webserver. The remote clients are using Windows XP and VISTA with OpenVPN 2.1.1.
I am new to VPNs and networking, but from my research, it seems as if this may be a routing issue. I would appreciate any help you may give in getting the remote clients to access the services on the LAN clients (other than the server @ 10.5.0.1).
Installed Ubuntu 10.04 on my Sony UX280p with Intel 4965 wireless. Ubuntu detects the card without issues (as far as I can tell). I can see all access points in my area and select my access point and pair with it. I get a DHCP address from the AP (if ifconfig is to be believed) and iwconfig shows the ESSID of my AP but I can't ping the AP or any other computer on the network, nor can I ping the sony from any other computer on my network. Last year I had installed 9.04 on this computer and wifi worked out of the box without any issues.
I posted this already in the absolute beginner section, but no answer was found, so I thought I might try this place..Long story as short as possible:
- I installed Ubuntu 9.10 for a friend who was fed up with WinXP crashing all the time
- After the install, networks was broken. I could ping sites outside the LAN, could connect to the router via firefox, but NO application could access the web. - The router works just fine, I tried with my own notebook.
- Disabling ipv6 in grub (edit /etc/default/grub and 'sudo update-grub') seemed to solve the problem.
- Then update the standard packages + install restricted extras and boom, Network gone: No ping to sites outside the LAN, no nothing. Still can connect fine to the router and even the remote desktop connection works, connecting over the internet. But that's it.
I have tried setting the mpu to a value recommended by my isp, I have set static ip and dns, I really don't now what to try any more.
I have two machines on this network, one running Ubuntu and the other running Fedora.
When I'm using the Wireless network on the Ubuntu machine, I cannot ping the Fedora machine. Everything else works. I can browse the net fine.
If I switch over to the Wired Network then I can ping the other machine.
I don't understand why ping doesn't work only over the Wireless. I can ping the router so I'm guessing it's getting blocked by the router but I didn't block ICMP traffic.
I tried asking on IRC and they ran out of ideas too to find out where the problem is.
I just installed my first EVER bind DNS server. I am running bind9 on Ubuntu 10.04. Everything seems to be working great except one thing: If I ping a host that I have set up in bind by its HOSTNAME the pings take 5-6 seconds to reply/print to the screen between each echo response. If I ping by the host's IP address, they echo back very quickly.
I have read that IPv6 can cause this, but I have disabled it in /etc/sysctl.conf and the problem still exists.
I know everyone says this can't be a DNS issue, but this never was an issue with dnsmasq (which i was using prior), and it doesn't make sense that the ping are ONLY slow when pinging by hostname and not IP.
Configs below:
Ping by hostname - there is a 5-6 second delay between each one of the responses:
Code:
Ping by IP - the responses come VERY quickly one after the other:
