Debian box listening on UDP port 68

[Jean-Sebastien Pilon]

Hello all,

I noticed that all my Debian boxes are listening on port 68/UDP if they
have the DHCP client running.

Can someone explain to me why they would listen on that port if they
actually received their DHCP info and they are up and running.

udp 0 0 0.0.0.0:68 0.0.0.0:*

is there any argument I need to pass to dhclient to fix this behavior ?

Thanks
NOTICE: This email contains privileged and confidential information and is intended only for the individual to whom it is addressed. If you are not the named addressee, you should not disseminate, distribute or copy this e-mail. Please notify the sender immediately by e-mail if you have received this transmission by mistake and delete this communication from your system. E-mail transmission cannot be guaranteed to be secured or error-free as information could be intercepted, corrupted, lost, destroyed, arrive late or incomplete, or contain viruses.

AVIS: Le pr�sent courriel contient des renseignements de nature privil�gi�e et confidentielle et n�est destin� qu'� la personne � qui il est adress�. Si vous n��tes pas le destinataire pr�vu, vous �tes par les pr�sentes avis�s que toute diffusion, distribution ou reproduction de cette communication est strictement interdite.� Si vous avez re�u ce courriel par erreur, veuillez en aviser imm�diatement l�exp�diteur et le supprimer de votre syst�me. Notez que la transmission de courriel ne peut en aucun cas �tre consid�r� comme inviolable ou exempt d�erreur puisque les informations qu�il contient pourraient �tre intercept�s, corrompues, perdues, d�truites, arriv�es en retard ou incompl�tes ou contenir un virus. �

[Roberto C. Sanchez]

Post by Jean-Sebastien Pilon
Hello all,
I noticed that all my Debian boxes are listening on port 68/UDP if they
have the DHCP client running.
Can someone explain to me why they would listen on that port if they
actually received their DHCP info and they are up and running.
udp 0 0 0.0.0.0:68 0.0.0.0:*
is there any argument I need to pass to dhclient to fix this behavior ?

It is probably that way since dhclient expects that it may need to
listen to the DHCP server if the lease is revoked or some other such thing.

Post by Jean-Sebastien Pilon
Thanks
NOTICE: This email contains privileged and confidential information and is intended only for the individual to whom it is addressed. If you are not the named addressee, you should not disseminate, distribute or copy this e-mail. Please notify the sender immediately by e-mail if you have received this transmission by mistake and delete this communication from your system. E-mail transmission cannot be guaranteed to be secured or error-free as information could be intercepted, corrupted, lost, destroyed, arrive late or incomplete, or contain viruses.
AVIS: Le présent courriel contient des renseignements de nature privilégiée et confidentielle et n’est destiné qu'à la personne à qui il est adressé. Si vous n’êtes pas le destinataire prévu, vous êtes par les présentes avisés que toute diffusion, distribution ou reproduction de cette communication est strictement interdite. Si vous avez reçu ce courriel par erreur, veuillez en aviser immédiatement l’expéditeur et le supprimer de votre système. Notez que la transmission de courriel ne peut en aucun cas être considéré comme inviolable ou exempt d’erreur puisque les informations qu’il contient pourraient être interceptés, corrompues, perdues, détruites, arrivées en retard ou incomplètes ou contenir un virus.

Please get rid of the above ridiculous notices or please post from a
different email address. About 66-75% of your message text is that
disclaimer, which by the way holds very little or no legal weight,
espcially considering you posted to a public mailing list with thousands
of recipients.

-Roberto

[Jean-Sebastien Pilon]

Post by Roberto C. Sanchez

Post by Jean-Sebastien Pilon
Hello all,
I noticed that all my Debian boxes are listening on port 68/UDP if

they

Post by Roberto C. Sanchez

Post by Jean-Sebastien Pilon
have the DHCP client running.
Can someone explain to me why they would listen on that port if they
actually received their DHCP info and they are up and running.
udp 0 0 0.0.0.0:68 0.0.0.0:*
is there any argument I need to pass to dhclient to fix this

behavior ?

Post by Roberto C. Sanchez
It is probably that way since dhclient expects that it may need to
listen to the DHCP server if the lease is revoked or some other such
thing.

Any ways to disable such behavior?

Post by Roberto C. Sanchez
Please get rid of the above ridiculous notices or please post from a
different email address. About 66-75% of your message text is that
disclaimer, which by the way holds very little or no legal weight,
espcially considering you posted to a public mailing list with

thousands

Post by Roberto C. Sanchez
of recipients.

Unfortunately this is appended automatically.

Post by Roberto C. Sanchez
-Roberto
--
Roberto C. Sanchez
http://familiasanchez.net/~roberto

NOTICE: This email contains privileged and confidential information and is intended only for the individual to whom it is addressed. If you are not the named addressee, you should not disseminate, distribute or copy this e-mail. Please notify the sender immediately by e-mail if you have received this transmission by mistake and delete this communication from your system. E-mail transmission cannot be guaranteed to be secured or error-free as information could be intercepted, corrupted, lost, destroyed, arrive late or incomplete, or contain viruses.

AVIS: Le pr�sent courriel contient des renseignements de nature privil�gi�e et confidentielle et n�est destin� qu'� la personne � qui il est adress�. Si vous n��tes pas le destinataire pr�vu, vous �tes par les pr�sentes avis�s que toute diffusion, distribution ou reproduction de cette communication est strictement interdite.� Si vous avez re�u ce courriel par erreur, veuillez en aviser imm�diatement l�exp�diteur et le supprimer de votre syst�me. Notez que la transmission de courriel ne peut en aucun cas �tre consid�r� comme inviolable ou exempt d�erreur puisque les informations qu�il contient pourraient �tre intercept�s, corrompues, perdues, d�truites, arriv�es en retard ou incompl�tes ou contenir un virus. �

[Greg Norris]

I suppose you could "kill -9" the dhclient process, once the interface
has been configured. You run the risk, however, of the DHCP server
reassigning your IP address to someone else, with no way for your
system to react. I wouldn't even consider doing this unless you also
control the DHCP server, and can ensure an appropriately long lease
time... even then, it's almost certainly a (very) bad idea.

In short, what you're seeing is perfectly normal behaviour for a box
which obtains it's IP address via DHCP. I strongly recommend that you
leave it alone.