LinuxQuestions.org - [SOLVED] How to detect eth0 status?

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How to detect eth0 status?

I have an ADSL modem connected to my Ethernet card. I use pppoe-start to connect to the Internet. I want to know whether my modem is switched on (i.e.,if eth0 is up) so that i can run pppoe-start because the pppoe-start script does not seem to check the state of eth0 and tries to start pppoe. Is there any command to know modem's status??

Welcome to LQ kakaburra!

ummm...try ifconfig in terminal

Quote:

ifconfig

and uh..I think you can look in /etc/resolvconf and somwhere in there is a file named resolv.conf

mine says

Code:

# Dynamic resolv.conf(5) file for glibc resolver(3) generated by resolvconf(8)

#    DO NOT EDIT THIS FILE BY HAND -- YOUR CHANGES WILL BE OVERWRITTEN

nameserver 71.252.0.12

nameserver 71.242.0.12

search linksys

however, also in /etc/dhcp3 or /etc/ifplugd

it matters what distro your using too

please tell us what distro and your computer specs?

Welcome to LQ
You can use
ifconfig

Quote:

Originally Posted by linus72 (Post 3644272)

Welcome to LQ kakaburra!

ummm...try ifconfig in terminal

and uh..I think you can look in /etc/resolvconf and somwhere in there is a file named resolv.conf

mine says

Code:

# Dynamic resolv.conf(5) file for glibc resolver(3) generated by resolvconf(8)

#    DO NOT EDIT THIS FILE BY HAND -- YOUR CHANGES WILL BE OVERWRITTEN

nameserver 71.252.0.12

nameserver 71.242.0.12

search linksys

however, also in /etc/dhcp3 or /etc/ifplugd

it matters what distro your using too

please tell us what distro and your computer specs?

Thankyou, but even if i switch off the modem, ifconfig still returns eth0's information.Output being

root@darkstar:/root# ifconfig

eth0 Link encap:Ethernet HWaddr 00:16:76:84:6e:c6
inet6 addr: fe80::216:76ff:fe84:6ec6/64 Scope:Link
UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1
RX packets:5935 errors:0 dropped:0 overruns:0 frame:0
TX packets:5940 errors:0 dropped:0 overruns:0 carrier:0
collisions:0 txqueuelen:1000
RX bytes:3341987 (3.1 MiB) TX bytes:1182225 (1.1 MiB)
Interrupt:23 Base address:0xb800

lo Link encap:Local Loopback
inet addr:127.0.0.1 Mask:255.0.0.0
inet6 addr: ::1/128 Scope:Host
UP LOOPBACK RUNNING MTU:16436 Metric:1
RX packets:786 errors:0 dropped:0 overruns:0 frame:0
TX packets:786 errors:0 dropped:0 overruns:0 carrier:0
collisions:0 txqueuelen:0
RX bytes:88176 (86.1 KiB) TX bytes:88176 (86.1 KiB)

ppp0 Link encap:Point-to-Point Protocol
inet addr:59.93.69.27 P-t-P:59.93.64.1 Mask:255.255.255.255
UP POINTOPOINT RUNNING NOARP MULTICAST MTU:1492 Metric:1
RX packets:233 errors:0 dropped:0 overruns:0 frame:0
TX packets:240 errors:0 dropped:0 overruns:0 carrier:0
collisions:0 txqueuelen:3
RX bytes:122686 (119.8 KiB) TX bytes:47759 (46.6 KiB)

I use Slackware 12.2.
There are no /etc/dhcp3 or /etc/ifplugd files.

Quote:

Originally Posted by repo (Post 3644273)

Welcome to LQ
You can use
ifconfig

Thankyou, but ifconfig doesn't help as i said in previous post.

NOT: My internet connection is perfectly fine. I just want to know my modem's status (i.e.,switched on/off ) so that i can write a script which automatically runs pppoe-start script if eth0 goes up.

can you post the output from ifconfig if the modem is connected, but pppoe isn't started ?

Quote:

Originally Posted by repo (Post 3644285)

can you post the output from ifconfig if the modem is connected, but pppoe isn't started ?

root@darkstar:/root# ifconfig
eth0 Link encap:Ethernet HWaddr 00:16:76:84:6e:c6
inet6 addr: fe80::216:76ff:fe84:6ec6/64 Scope:Link
UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1
RX packets:6466 errors:0 dropped:0 overruns:0 frame:0
TX packets:6431 errors:0 dropped:0 overruns:0 carrier:0
collisions:0 txqueuelen:1000
RX bytes:3548870 (3.3 MiB) TX bytes:1319848 (1.2 MiB)
Interrupt:23 Base address:0xb800

lo Link encap:Local Loopback
inet addr:127.0.0.1 Mask:255.0.0.0
inet6 addr: ::1/128 Scope:Host
UP LOOPBACK RUNNING MTU:16436 Metric:1
RX packets:786 errors:0 dropped:0 overruns:0 frame:0
TX packets:786 errors:0 dropped:0 overruns:0 carrier:0
collisions:0 txqueuelen:0
RX bytes:88176 (86.1 KiB) TX bytes:88176 (86.1 KiB)

As you can see, if pppoe is not started, it doesn't show up in ifconfig's output, but eth0 is always been showed.

You could try to look in

Code:

/var/log/messages

Code:

dmesg

to see if you find a line when the modem is switched on, and go from there

@repo

Thankyou. The last few lines of /var/log/messages and dmesg do help.

The link status from

Code:

ethtool eth0

might be another way for you to check.

@ mRgOBLIN

Thankyou, that also works.