[Discuss] network issue

[nuno at aeminium.org (Nuno Sucena Almeida)]

I'll add a few things:

- if using mixed gigabit/megabit switches or network cards, make sure
the ethernet cable is in good condition and that the computer/switch is
able to negotiate the speed. I've seen issues with this in the past, use
the already mentioned ethtool and look for out of place values and link
status.

- if it's a cheap router/switch, some models share two ethernet jacks
between the wan and lan for the same port: when the wan port is
connected, the lan or even both jacks won't work anymore. Testing that
same port and cable with another computer and knowing the router/switch
model would be helpful.

- also mentioned, use 'tcpdump -n -A -XX -i eth0' to look for bootpc
requests.

regards,
Nuno


On 03/14/2014 09:24 AM, Kevin D. Clark wrote:
> 
> [dhcp problems]
> 
> How about typing:
> 
>   date
>  
>   ifconfig eth0
> 
>   sudo ethtool eth0
>   (or perhaps "sudo mii-tool eth0")
> 
>   ethtool -i eth0
> 
>   ps -elf | grep dhcp
> 
>   sudo tcpdump -v -i eth0 \
>       'arp or icmp or udp port 67 or udp port 68' \
>       >/tmp/capture.txt &
> 
>   ifdown eth0
> 
>   ifup eth0
> 
>   ifconfig
> 
>   ps -elf | grep dhcp
> 
>   ls -l /etc/resolv.conf
> 
>   cat /etc/resolv.conf
> 
>   sudo ping -b 255.255.255.255
>     (press control-c after ~5 seconds...)
> 
>   ping www.google.com
> 
>   fg
> 
>   cat /tmp/capture.txt
> 
> 
> Regards,
> 
> --kevin
> 


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