Why aren't you just deleting the lease file on shutdown?
On Dec 8, 2014 10:04 AM, "Jurjen Oskam" <jur...@osk.am> wrote:
> Hi,
>
> My (residential) ISP assigns me an IP address using DHCP. The lease time
> is 7
> days or so. I just put "dhcp" in hostname.re1 and everything works, except
> for
> a minor annoyance.
>
> When re1 goes down (e.g. because of a reboot) the ISP *requires* a
> successful
> DHCP exchange to occur before it enables the link on a layer 3 level. It
> does
> not matter whether there still is a valid lease or not: after re1 goes
> down,
> there *has* to be a DHCP exchange otherwise the link won't work.
>
> What makes this worse is that the DHCP server does not always immediately
> respond after re1 comes back up. It regularly happens that dhclient
> concludes
> that the DHCP server is unreachable, finds that it still has a valid lease
> in the lease file, and it'll use that. The problem with this is that
> dhclient
> doesn't seem to try to contact the server anymore. With long lease times,
> it
> could take days for dhclient to try to renew the lease.
>
> I've tried using "timeout 0" in dhclient.conf, but that only causes
> dhclient
> to immediately using the lease from the lease file (after trying to
> reacquire
> its previous address for ten seconds). Using an arbitrarily high timeout
> value doesn't seem right.
>
> The retry setting doesn't seem to help in this case: by default it's set to
> 5 minutes, but in my testing I noticed that once dhclient is bound to a
> lease
> from the lease file, this setting doesn't seem to be used anymore.
>
>
> Perhaps I've missed something, but I concluded that in my scenario lease
> files are never useful. I modified dhclient to accept a new option called
> "no-lease-file" in dhclient.conf. A diff against -current is below. I've
> tested it lightly on a laptop, and it seems to work OK. I've been using
> roughly the same diff against -stable for a day or two.
>
>
> Index: sbin/dhclient/clparse.c
> ===================================================================
> RCS file: /cvs/src/sbin/dhclient/clparse.c,v
> retrieving revision 1.90
> diff -u -p -r1.90 clparse.c
> --- sbin/dhclient/clparse.c 3 Nov 2014 22:06:39 -0000 1.90
> +++ sbin/dhclient/clparse.c 8 Dec 2014 10:07:39 -0000
> @@ -67,6 +67,7 @@ read_client_conf(void)
> new_parse(path_dhclient_conf);
>
> /* Set some defaults. */
> + config->use_lease_file = 1;
> config->link_timeout = 10;
> config->timeout = 60;
> config->select_interval = 0;
> @@ -153,6 +154,7 @@ read_client_leases(void)
> * TOK_BACKOFF_CUTOFF number |
> * TOK_INITIAL_INTERVAL number |
> * interface-declaration |
> + * TOK_NO_LEASE_FILE |
> * TOK_LEASE client-lease-statement |
> * TOK_ALIAS client-lease-statement |
> * TOK_REJECT reject-statement
> @@ -240,6 +242,10 @@ parse_client_statement(FILE *cfile)
> break;
> case TOK_INTERFACE:
> parse_interface_declaration(cfile);
> + break;
> + case TOK_NO_LEASE_FILE:
> + config->use_lease_file = 0;
> + parse_semi(cfile);
> break;
> case TOK_LEASE:
> parse_client_lease_statement(cfile, 1);
> Index: sbin/dhclient/conflex.c
> ===================================================================
> RCS file: /cvs/src/sbin/dhclient/conflex.c,v
> retrieving revision 1.29
> diff -u -p -r1.29 conflex.c
> --- sbin/dhclient/conflex.c 5 May 2014 18:02:49 -0000 1.29
> +++ sbin/dhclient/conflex.c 8 Dec 2014 10:07:39 -0000
> @@ -352,6 +352,7 @@ static const struct keywords {
> { "media", TOK_MEDIA },
> { "medium", TOK_MEDIUM },
> { "next-server", TOK_NEXT_SERVER },
> + { "no-lease-file", TOK_NO_LEASE_FILE },
> { "option", TOK_OPTION },
> { "prepend", TOK_PREPEND },
> { "rebind", TOK_REBIND },
> Index: sbin/dhclient/dhclient.c
> ===================================================================
> RCS file: /cvs/src/sbin/dhclient/dhclient.c,v
> retrieving revision 1.343
> diff -u -p -r1.343 dhclient.c
> --- sbin/dhclient/dhclient.c 8 Dec 2014 02:04:58 -0000 1.343
> +++ sbin/dhclient/dhclient.c 8 Dec 2014 10:07:39 -0000
> @@ -549,15 +549,17 @@ main(int argc, char *argv[])
> close(tailfd);
> }
>
> - if ((fd = open(path_dhclient_db,
> - O_RDONLY|O_EXLOCK|O_CREAT|O_NOFOLLOW, 0640)) == -1)
> - error("can't open and lock %s: %s", path_dhclient_db,
> - strerror(errno));
> - read_client_leases();
> - if ((leaseFile = fopen(path_dhclient_db, "w")) == NULL)
> - error("can't open %s: %s", path_dhclient_db,
> strerror(errno));
> - rewrite_client_leases();
> - close(fd);
> + if (config->use_lease_file) {
> + if ((fd = open(path_dhclient_db,
> + O_RDONLY|O_EXLOCK|O_CREAT|O_NOFOLLOW, 0640)) == -1)
> + error("can't open and lock %s: %s",
> path_dhclient_db,
> + strerror(errno));
> + read_client_leases();
> + if ((leaseFile = fopen(path_dhclient_db, "w")) == NULL)
> + error("can't open %s: %s", path_dhclient_db,
> strerror(errno));
> + rewrite_client_leases();
> + close(fd);
> + }
>
> if ((routefd = socket(PF_ROUTE, SOCK_RAW, 0)) == -1)
> error("socket(PF_ROUTE, SOCK_RAW): %s", strerror(errno));
> @@ -986,7 +988,8 @@ newlease:
> client->state = S_BOUND;
>
> /* Write out new leases file. */
> - rewrite_client_leases();
> + if (config->use_lease_file)
> + rewrite_client_leases();
>
> /* Set timeout to start the renewal process. */
> set_timeout(client->active->renewal, state_bound);
> Index: sbin/dhclient/dhclient.conf.5
> ===================================================================
> RCS file: /cvs/src/sbin/dhclient/dhclient.conf.5,v
> retrieving revision 1.31
> diff -u -p -r1.31 dhclient.conf.5
> --- sbin/dhclient/dhclient.conf.5 11 Nov 2013 15:39:20 -0000
> 1.31
> +++ sbin/dhclient/dhclient.conf.5 8 Dec 2014 10:07:39 -0000
> @@ -406,6 +406,14 @@ specified name.
> Interfaces for which there is no interface declaration will use the
> parameters declared outside of any interface declaration,
> or the default settings.
> +.It Ic no-lease-file ;
> +The
> +.Ic no-lease-file
> +statement causes the DHCP client to not write a lease file on being
> +assigned a lease, and to ignore an existing lease file.
> +This should be used when the other end of a link requires a successful
> +DHCP exchange before making the link fully functional, even when a
> +valid lease from a previous DHCP exchange still exists.
> .El
> .Sh EXAMPLES
> The following configuration file is used on a laptop
> Index: sbin/dhclient/dhcpd.h
> ===================================================================
> RCS file: /cvs/src/sbin/dhclient/dhcpd.h,v
> retrieving revision 1.145
> diff -u -p -r1.145 dhcpd.h
> --- sbin/dhclient/dhcpd.h 5 Dec 2014 15:47:05 -0000 1.145
> +++ sbin/dhclient/dhcpd.h 8 Dec 2014 10:07:39 -0000
> @@ -136,6 +136,7 @@ struct client_config {
> int requested_option_count;
> int required_option_count;
> int ignored_option_count;
> + u_int8_t use_lease_file;
> time_t timeout;
> time_t initial_interval;
> time_t link_timeout;
> Index: sbin/dhclient/dhctoken.h
> ===================================================================
> RCS file: /cvs/src/sbin/dhclient/dhctoken.h,v
> retrieving revision 1.9
> diff -u -p -r1.9 dhctoken.h
> --- sbin/dhclient/dhctoken.h 5 Dec 2013 22:31:35 -0000 1.9
> +++ sbin/dhclient/dhctoken.h 8 Dec 2014 10:07:39 -0000
> @@ -78,6 +78,7 @@
> #define TOK_REJECT 292
> #define TOK_LINK_TIMEOUT 294
> #define TOK_IGNORE 295
> +#define TOK_NO_LEASE_FILE 296
>
> #define is_identifier(x) ((x) >= TOK_FIRST_TOKEN && \
> (x) != TOK_STRING && \
>
>
>
>
>
>
>
>
> Regards,
>
> Jurjen Oskam
>
>
