Pull up following revision(s) (requested by kim in ticket #1643):

etc/rc.d/sshd: revision 1.30
	etc/rc.d/sshd: revision 1.33
	etc/rc.d/sshd: revision 1.34
	etc/rc.d/sshd: revision 1.35

simplify more (from rudolf)

/etc/rc.d/sshd: New check cmd and reload precmd.
- check cmd: run `sshd -t' to check sshd_config file
- reload precmd: run check cmd before reloading so we don't nuke sshd
  if there's an error in the sshd_config file

(It is still possible to effectively nuke sshd by changing the
configuration tosomething that won't work on your network, but at
least we avoid making sshd just exit on reload when you make a typo
in a config option.)

/etc/rc.d/sshd: Stop generating DSA host keys by default.
If you want them you can generate them yourself, but in this day and
age (Monday and 2023, specifically) there's no reason to be using DSA
except for compatibility with ancient legacy software.
/etc/rc.d/sshd: Use default curve for ECDSA keygen, not NIST P-521.

The default is NIST P-256, which:
(a) has plenty of cryptanalytic security,
(b) performs better on essentially all platforms (smaller enough that
    even the advantage of the Mersenne prime structure of P-521 can't
    compete), and
(c) likely gets more scrutiny on implementations than P-521 since it's
    more widespread.

etc/rc.d/sshd

@@ -1,6 +1,6 @@
 #!/bin/sh
 #
-# $NetBSD: sshd,v 1.29 2018/05/26 19:18:11 riastradh Exp $
+# $NetBSD: sshd,v 1.29.4.1 2023/06/21 16:06:14 martin Exp $
 #
 
 # PROVIDE: sshd
@@ -13,14 +13,14 @@ rcvar=$name
 command="/usr/sbin/${name}"
 pidfile="/var/run/${name}.pid"
 required_files="/etc/ssh/sshd_config"
-extra_commands="keygen reload"
+extra_commands="check keygen reload"
 
 sshd_keygen()
 {
 (
 	keygen="/usr/bin/ssh-keygen"
 	umask 022
-	while read type bits filename version name;  do
+	while read type bits filename;  do
 		f="/etc/ssh/$filename"
 		if [ -f "$f" ]; then
 			continue
@@ -33,10 +33,9 @@ sshd_keygen()
 		"${keygen}" -t "${type}" ${bitarg} -f "${f}" -N '' -q && \
 		    printf "ssh-keygen: " && "${keygen}" -f "${f}" -l
 	done << _EOF
-dsa	1024	ssh_host_dsa_key	2	DSA
-ecdsa	521	ssh_host_ecdsa_key	1	ECDSA
-ed25519	-1	ssh_host_ed25519_key	1	ED25519
-rsa	0	ssh_host_rsa_key	2	RSA
+ecdsa	-1	ssh_host_ecdsa_key
+ed25519	-1	ssh_host_ed25519_key
+rsa	0	ssh_host_rsa_key
 _EOF
 )
 }
@@ -46,7 +45,19 @@ sshd_precmd()
 	run_rc_command keygen
 }
 
+sshd_check()
+{
+	sshd -t
+}
+
+sshd_reload_precmd()
+{
+	run_rc_command check
+}
+
+check_cmd=sshd_check
 keygen_cmd=sshd_keygen
+reload_precmd=sshd_reload_precmd
 start_precmd=sshd_precmd
 
 load_rc_config $name