Network connection diagnostics
in [Linux Networking]
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From: Marco A. Cruz Quevedo on 19 Sep 2006 02:05 Is there a quick or practical way to check a network connection? I mean, to get IP, gateway address, etc, and to know what is going wrong. When I just log on, I cannot get to internet, unles I manually issue ifdown eth0, ifup eth0, service network restart. Thanks Marco --------------------- Freedom is not a permission for chaos.
From: Stanislaw Flatto on 19 Sep 2006 04:03 Marco A. Cruz Quevedo wrote: > Is there a quick or practical way to check a network connection? I > mean, to get IP, gateway address, etc, and to know what is going wrong. > When I just log on, I cannot get to internet, unles I manually issue > ifdown eth0, ifup eth0, service network restart. > > Thanks > > Marco You can activate the hardware from command prompt. So, there is NOTHING wrong with the network. I would line up different configuration files and teach _them_ how to behave. Have luck Stanislaw Slack user from Ulladulla.
From: Marco A. Cruz Quevedo on 19 Sep 2006 11:09 Stanislaw Flatto wrote: > Marco A. Cruz Quevedo wrote: > > Is there a quick or practical way to check a network connection? I > > mean, to get IP, gateway address, etc, and to know what is going wrong. > > When I just log on, I cannot get to internet, unles I manually issue > > ifdown eth0, ifup eth0, service network restart. > > > > Thanks > > > > Marco > > You can activate the hardware from command prompt. > So, there is NOTHING wrong with the network. > I would line up different configuration files and teach _them_ how to > behave. > I have to make all this steps AFTER I was updating some software packages to my Linux box. The network was ready whe I just logged in, but now the netowrk does not respond, unless I perform the steps mentioned above. I know I have to check ALL network related files, so I can get to know what is wrong, why the network is not ready when I log into my system. Regards, Marco > Have luck > > Stanislaw > Slack user from Ulladulla.
From: Moe Trin on 19 Sep 2006 15:56 Followup-To set to comp.os.linux.networking - not applicable to comp.os.linux.misc - and a stretch for comp.os.linux.setup On 18 Sep 2006, in the Usenet newsgroup comp.os.linux.networking, in article <1158645950.917227.275410(a)m73g2000cwd.googlegroups.com>, Marco A. Cruz Quevedo wrote: >Is there a quick or practical way to check a network connection? I >mean, to get IP, gateway address, etc, and to know what is going wrong. /sbin/ifconfig -a /sbin/route -n cat /etc/resolv.conf >When I just log on, I cannot get to internet, unles I manually issue >ifdown eth0, ifup eth0, service network restart. What distribution - what release? What type of connection to the ISP? This sounds as if your network configuration scripts are not set correctly, but there isn't enough information to tell which one[s]. Old guy
From: david on 20 Sep 2006 21:03
On 18 Sep 2006 23:05:50 -0700, "Marco A. Cruz Quevedo" <macruzq(a)myway.com> wrote: >Is there a quick or practical way to check a network connection? I >mean, to get IP, gateway address, etc, and to know what is going wrong. >When I just log on, I cannot get to internet, unles I manually issue >ifdown eth0, ifup eth0, service network restart. > >Thanks > >Marco > >--------------------- >Freedom is not a permission for chaos. ifconfig -a shows interfaces (NICs or "adapters"), including their IP if they have one. route -n shows the routing table, including the default route if there is one, which default route contains the gateway address. For example, below, the eth0 NIC's IP is 192.168.3.12. If that line is missing your NIC lacks an IP. And the gateway address is 192.168.3.2. The default route is the route to "0.0.0.0" and you see that address in that route's line item in the table. Maybe your service network restart is triggering an address request (ie running a dhcp client), but that's not taking place as part of the boot process. Check /etc/sysconfig/network for something like ONBOOT=no (or yes). If it's no, it's configured to omit setting up network stuff as part of booting. Check also for something like BOOTPROTO=dhcp (I think) to see whether, when the network config is performed it entails use of dhcp. To experiment with running dhcp client manually, the name of the client is usually dhclient, otherwise there's one called pump and one called dhcpcd. Your system might have one or another of those. Example: [root(a)hostx ~]# ifconfig eth0 eth0 Link encap:Ethernet HWaddr 00:02:B3:41:86:F9 inet addr:192.168.3.12 Bcast:192.168.3.255 Mask:255.255.255.0 inet6 addr: fe80::202:b3ff:fe41:86f9/64 Scope:Link UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1 RX packets:8038 errors:0 dropped:0 overruns:0 frame:0 TX packets:5327 errors:0 dropped:0 overruns:0 carrier:0 collisions:0 txqueuelen:1000 RX bytes:10726255 (10.2 MiB) TX bytes:377137 (368.2 KiB) [root(a)hostx ~]# route -n Kernel IP routing table Destination Gateway Genmask Flags Metric Ref Use Iface 192.168.3.0 0.0.0.0 255.255.255.0 U 0 0 0 eth0 0.0.0.0 192.168.3.2 0.0.0.0 UG 0 0 0 eth0 [root(a)hostx ~]# |