lwresd

Name

lwresd — lightweight resolver daemon

Synopsis

lwresd [-c config-file] [-C config-file] [-d debug-level] [-f] [-g] [-i pid-file] [-m flag] [-n #cpus] [-P port] [-p port] [-s] [-t directory] [-u user] [-v] [-4] [-6]

DESCRIPTION

lwresd + is the daemon providing name lookup + services to clients that use the BIND 9 lightweight resolver + library. It is essentially a stripped-down, caching-only name + server that answers queries using the BIND 9 lightweight + resolver protocol rather than the DNS protocol. +

lwresd + listens for resolver queries on a + UDP port on the IPv4 loopback interface, 127.0.0.1. This + means that lwresd can only be used by + processes running on the local machine. By default UDP port + number 921 is used for lightweight resolver requests and + responses. +

+ Incoming lightweight resolver requests are decoded by the + server which then resolves them using the DNS protocol. When + the DNS lookup completes, lwresd encodes + the answers in the lightweight resolver format and returns + them to the client that made the request. +

+ If /etc/resolv.conf contains any + nameserver entries, lwresd + sends recursive DNS queries to those servers. This is similar + to the use of forwarders in a caching name server. If no + nameserver entries are present, or if + forwarding fails, lwresd resolves the + queries autonomously starting at the root name servers, using + a built-in list of root server hints. +

OPTIONS

-4: + Use IPv4 only even if the host machine is capable of IPv6. + -4 and -6 are mutually + exclusive. +
-6: + Use IPv6 only even if the host machine is capable of IPv4. + -4 and -6 are mutually + exclusive. +
-c config-file: + Use config-file as the + configuration file instead of the default, + /etc/lwresd.conf. + + -c can not be used with -C. +
-C config-file: + Use config-file as the + configuration file instead of the default, + /etc/resolv.conf. + -C can not be used with -c. +
-d debug-level: + Set the daemon's debug level to debug-level. + Debugging traces from lwresd become + more verbose as the debug level increases. +
-f: + Run the server in the foreground (i.e. do not daemonize). +
-g: + Run the server in the foreground and force all logging + to stderr. +
-i pid-file: + Use pid-file as the + PID file instead of the default, + /var/run/lwresd/lwresd.pid. +
-m flag: + Turn on memory usage debugging flags. Possible flags are + usage, + trace, + record, + size, and + mctx. + These correspond to the ISC_MEM_DEBUGXXXX flags described in + <isc/mem.h>. +
-n #cpus: + Create #cpus worker threads + to take advantage of multiple CPUs. If not specified, + lwresd will try to determine the + number of CPUs present and create one thread per CPU. + If it is unable to determine the number of CPUs, a + single worker thread will be created. +
-P port: + Listen for lightweight resolver queries on port + port. If + not specified, the default is port 921. +
-p port: + Send DNS lookups to port port. If not + specified, the default is port 53. This provides a + way of testing the lightweight resolver daemon with a + name server that listens for queries on a non-standard + port number. +
-s: +
+ Write memory usage statistics to stdout + on exit. +
+
+
Note
+
+ This option is mainly of interest to BIND 9 developers + and may be removed or changed in a future release. +
+
+
-t directory: +
Chroot + to directory after + processing the command line arguments, but before + reading the configuration file. +
+
+
Warning
+
+ This option should be used in conjunction with the + -u option, as chrooting a process + running as root doesn't enhance security on most + systems; the way chroot(2) is + defined allows a process with root privileges to + escape a chroot jail. +
+
+
-u user: Setuid + to user after completing + privileged operations, such as creating sockets that + listen on privileged ports. +
-v: + Report the version number and exit. +

FILES

/etc/resolv.conf: + The default configuration file. +
/var/run/lwresd.pid: + The default process-id file. +

AUTHOR

Internet Systems Consortium +

Name

Synopsis

DESCRIPTION

OPTIONS

Note

Warning

FILES

SEE ALSO

AUTHOR