New Linux User

12 opinions for HOWTO: Manually Ask my DHCP Server for an IP Address?

• stranger
  Oct 13, 2005 at 8:14 am

  It’s ‘dhcpcd’. ‘dhcpd’ is the server daemon; dhcpcd is one of the many implementations of the client.

• Jon
  Oct 13, 2005 at 8:32 am

  Wha??

  I’ll have to try this when I get back to my GNU/Linux box. I use dhclient right now, but I swear back when I used it, I just typed ‘dhcpd’ and off it went.

  I’ll check and correct the article if required.

  Thanks for the info!

• Jon
  Oct 13, 2005 at 7:35 pm

  I just checked on my Kanotix (Debian) box at home. When I type ‘dhcpcd’ I get nothing. When I type ‘dhcpd’ I get the expected output.

  So…I’m lost. Can you explain what you mean by the ‘dhcpcd’ comment?

  Thanks!

• New Linux User » HOWTO: Use Ifconfig.
  Nov 9, 2005 at 8:12 pm

  […] Requesting an IP address Managing a wireless network card This entry was posted on Wednesday, November 9th, 2005 and is filed under How To. You can follow any responses to this entry through the RSS 2.0 feed. You can leave a response, or trackback from your own site. […]

• phily
  Nov 29, 2005 at 1:55 pm

  I just tried command ‘dhclient’.
  So, I have to confirm that
  I had to do it as root.
  It worked both /sbin/dhclient eth0 and /sbin/dhclient, i.e. both of them returned the same results.
  Greetings
  phil
  ps. Is it possible to get know the outside IP. I got LAN, so dhclient command returns my IP and some router where my IP is obtained from. Of course I know IP of my server, but is any command that can retrive this information?

• Jon
  Nov 29, 2005 at 2:09 pm

  Hi Phil,

  Thanks for the information. I think the two differences between dhclient eth0 and just dhclient is that dhclient alone will try to obtain an IP address for ALL your network interfaces (not the lo localhost, though). So, if you’re like me and only have one network card, then both commands will indeed return the same results.

  Good question about the outside IP. I don’t know if that information is generally available to inside clients. I’ll see what I can find out.

• geoff
  Nov 29, 2005 at 7:55 pm

  You could always do this:

  $ curl -s http://checkip.dyndns.org/ | grep -i address

  Dirty, but quick and easy.

• phily
  Nov 30, 2005 at 9:36 am

  Hi Geoff,
  Thanks. It is a good one, but the address is retrieved from outside… I want to do it from inside, i.e. to retrieve IP from my server…
  Greetings
  phily

• geoff
  Dec 1, 2005 at 12:08 am

  None of the software running inside your PC can “give out” your network’s public IP address because it is completely unknown to your machines! Only the NAT router knows the public IP of your network, your machines only know their private “behind the router” IP’s.

  From Shields Up!.

• Jon
  Dec 1, 2005 at 5:40 am

  Hi Geoff,

  That’s kind of what I was pondering in my comment above. However, I’ll bet you that a clever hacker can figure out how to get it.

  Since my external IP is shown on my router’s admin page, it seems to me that information could be scraped off it and used.

  It’s an interesting thought.

• geoff
  Dec 1, 2005 at 4:17 pm

  I guess, as above, you could curl the router’s HTML page and grep for the particular line. That would, theoretically, be obtaining the external address from within the server.

  $ curl -s http://192.168.0.1/st_device.html | grep -i “IP address”

  This should work for me, except that I cannot get passed the authorization step (even using -u in curl).

• Jon
  Dec 1, 2005 at 8:56 pm

  For my Linksys, a url like:

  http://username:password@192.168.100.1 logs me in.

  Actually, to be more specific, I don’t have a username, just a password. Therefore:

  http://null:password@192.168.200.1 works for me.

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