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Diffstat (limited to 'upstream/fedora-40/man8/nss-resolve.8')
| -rw-r--r-- | upstream/fedora-40/man8/nss-resolve.8 | 174 |
1 files changed, 174 insertions, 0 deletions
diff --git a/upstream/fedora-40/man8/nss-resolve.8 b/upstream/fedora-40/man8/nss-resolve.8 new file mode 100644 index 00000000..5c12c8d4 --- /dev/null +++ b/upstream/fedora-40/man8/nss-resolve.8 @@ -0,0 +1,174 @@ +'\" t +.TH "NSS\-RESOLVE" "8" "" "systemd 255" "nss-resolve" +.\" ----------------------------------------------------------------- +.\" * Define some portability stuff +.\" ----------------------------------------------------------------- +.\" ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ +.\" http://bugs.debian.org/507673 +.\" http://lists.gnu.org/archive/html/groff/2009-02/msg00013.html +.\" ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ +.ie \n(.g .ds Aq \(aq +.el .ds Aq ' +.\" ----------------------------------------------------------------- +.\" * set default formatting +.\" ----------------------------------------------------------------- +.\" disable hyphenation +.nh +.\" disable justification (adjust text to left margin only) +.ad l +.\" ----------------------------------------------------------------- +.\" * MAIN CONTENT STARTS HERE * +.\" ----------------------------------------------------------------- +.SH "NAME" +nss-resolve, libnss_resolve.so.2 \- Hostname resolution via systemd\-resolved\&.service +.SH "SYNOPSIS" +.PP +libnss_resolve\&.so\&.2 +.SH "DESCRIPTION" +.PP +\fBnss\-resolve\fR +is a plug\-in module for the GNU Name Service Switch (NSS) functionality of the GNU C Library (\fBglibc\fR) enabling it to resolve hostnames via the +\fBsystemd-resolved\fR(8) +local network name resolution service\&. It replaces the +\fBnss\-dns\fR +plug\-in module that traditionally resolves hostnames via DNS\&. +.PP +To activate the NSS module, add +"resolve\ \&[!UNAVAIL=return]" +to the line starting with +"hosts:" +in +/etc/nsswitch\&.conf\&. Specifically, it is recommended to place +"resolve" +early in +/etc/nsswitch\&.conf\*(Aqs +"hosts:" +line\&. It should be before the +"files" +entry, since +systemd\-resolved +supports +/etc/hosts +internally, but with caching\&. To the contrary, it should be after +"mymachines", to give hostnames given to local VMs and containers precedence over names received over DNS\&. Finally, we recommend placing +"dns" +somewhere after +"resolve", to fall back to +\fBnss\-dns\fR +if +systemd\-resolved\&.service +is not available\&. +.PP +Note that +\fBsystemd\-resolved\fR +will synthesize DNS resource records in a few cases, for example for +"localhost" +and the current local hostname, see +\fBsystemd-resolved\fR(8) +for the full list\&. This duplicates the functionality of +\fBnss-myhostname\fR(8), but it is still recommended (see examples below) to keep +\fBnss\-myhostname\fR +configured in +/etc/nsswitch\&.conf, to keep those names resolveable if +\fBsystemd\-resolved\fR +is not running\&. +.PP +Please keep in mind that +\fBnss\-myhostname\fR +(and +\fBnss\-resolve\fR) also resolve in the other direction \(em from locally attached IP addresses to hostnames\&. If you rely on that lookup being provided by DNS, you might want to order things differently\&. +.PP +Communication between +\fBnss\-resolve\fR +and +systemd\-resolved\&.service +takes place via the +/run/systemd/resolve/io\&.systemd\&.Resolve +\fBAF_UNIX\fR +socket\&. +.SH "ENVIRONMENT VARIABLES" +.PP +\fI$SYSTEMD_NSS_RESOLVE_VALIDATE\fR +.RS 4 +Takes a boolean argument\&. When false, cryptographic validation of resource records via DNSSEC will be disabled\&. This may be useful for testing, or when system time is known to be unreliable\&. +.sp +Added in version 250\&. +.RE +.PP +\fI$SYSTEMD_NSS_RESOLVE_SYNTHESIZE\fR +.RS 4 +Takes a boolean argument\&. When false, synthetic records, e\&.g\&. for the local host name, will not be returned\&. See section SYNTHETIC RECORDS in +\fBsystemd-resolved.service\fR(8) +for more information\&. This may be useful to query the "public" resource records, independent of the configuration of the local machine\&. +.sp +Added in version 250\&. +.RE +.PP +\fI$SYSTEMD_NSS_RESOLVE_CACHE\fR +.RS 4 +Takes a boolean argument\&. When false, the cache of previously queried records will not be used by +\fBsystemd-resolved\fR(8)\&. +.sp +Added in version 250\&. +.RE +.PP +\fI$SYSTEMD_NSS_RESOLVE_ZONE\fR +.RS 4 +Takes a boolean argument\&. When false, answers using locally registered public LLMNR/mDNS resource records will not be returned\&. +.sp +Added in version 250\&. +.RE +.PP +\fI$SYSTEMD_NSS_RESOLVE_TRUST_ANCHOR\fR +.RS 4 +Takes a boolean argument\&. When false, answers using locally configured trust anchors will not be used\&. +.sp +Added in version 250\&. +.RE +.PP +\fI$SYSTEMD_NSS_RESOLVE_NETWORK\fR +.RS 4 +Takes a boolean argument\&. When false, answers will be returned without using the network, i\&.e\&. either from local sources or the cache in +\fBsystemd-resolved\fR(8)\&. +.sp +Added in version 250\&. +.RE +.SH "EXAMPLE" +.PP +Here is an example +/etc/nsswitch\&.conf +file that enables +\fBnss\-resolve\fR +correctly: +.sp +.if n \{\ +.RS 4 +.\} +.nf +passwd: files systemd +group: files [SUCCESS=merge] systemd +shadow: files systemd +gshadow: files systemd + +hosts: mymachines \fBresolve [!UNAVAIL=return]\fR files myhostname dns +networks: files + +protocols: db files +services: db files +ethers: db files +rpc: db files + +netgroup: nis +.fi +.if n \{\ +.RE +.\} +.SH "SEE ALSO" +.PP +\fBsystemd\fR(1), +\fBsystemd-resolved\fR(8), +\fBnss-systemd\fR(8), +\fBnss-myhostname\fR(8), +\fBnss-mymachines\fR(8), +\fBnsswitch.conf\fR(5), +\fBsystemd.syntax\fR(5) |