sshdのmatchでグループ単位のchrootをさせると「-T」 拡張テストモードでエラー

# 前提
- CentOS8
- OpenSSH_8.0p1, OpenSSL 1.1.1g FIPS  21 Apr 2020

# sshdのmatchでグループ単位のchroot設定し、テストコマンド実行するとエラーが発生

```/etc/ssh/sshd_config.
Subsystem sftp internal-sftp

Match Group sftp-group
	ChrootDirectory /mnt/sftp-user/%u
	X11Forwarding no
	AllowTcpForwarding no
	PasswordAuthentication yes
	ForceCommand internal-sftp
	AuthorizedKeysFile /home/%u/.ssh/authorized_keys
```

```
# sshd -T
'Match Group' in configuration but 'user' not in connection test specification.
```

# マニュアル読め

```
# man sshd

    -C connection_spec
             -T 拡張テストモードを使用するための接続パラメータを指定します。提
             供されるなら、設定が標準出力に書き込まれる前に、指定されたユー
             ザ、ホスト、とアドレスに適用される設定ファイルの任意の Match 指示
             は、設定されます。接続パラメータは、keyword=value の組で提供され
             ます。キーワードは、``user'', ``host'', ``laddr'', ``lport'' と
             ``addr'' です。すべてが必要であり、複数の -C オプション、または、
             コンマで区切られたリストとして、順不同で供給されます。
```

# 試してみる

```
# sshd -T -C user=root -C host=localhost -C addr=localhost
port 22
addressfamily any
listenaddress [::]:22
listenaddress 0.0.0.0:22
usepam yes
logingracetime 120
x11displayoffset 10
x11maxdisplays 1000
maxauthtries 6
maxsessions 10
clientaliveinterval 0
clientalivecountmax 3
streamlocalbindmask 0177
permitrootlogin no
ignorerhosts yes
ignoreuserknownhosts no
hostbasedauthentication no
hostbasedusesnamefrompacketonly no
pubkeyauthentication yes
kerberosauthentication no
kerberosorlocalpasswd yes
kerberosticketcleanup yes
kerberosuniqueccache no
kerberosusekuserok yes
gssapienablek5users no
gssapiauthentication no
gssapicleanupcredentials no
gssapikeyexchange no
gssapistrictacceptorcheck yes
gssapistorecredentialsonrekey no
gssapikexalgorithms gss-group14-sha256-,gss-group16-sha512-,gss-nistp256-sha256-,gss-curve25519-sha256-,gss-group14-sha1-,gss-gex-sha1-
passwordauthentication no
kbdinteractiveauthentication no
challengeresponseauthentication no
printmotd no
printlastlog yes
x11forwarding no
x11uselocalhost yes
permittty yes
permituserrc yes
strictmodes yes
tcpkeepalive yes
permitemptypasswords no
compression yes
gatewayports no
usedns no
allowtcpforwarding yes
allowagentforwarding yes
disableforwarding no
allowstreamlocalforwarding yes
streamlocalbindunlink no
fingerprinthash SHA256
exposeauthinfo no
pidfile /var/run/sshd.pid
xauthlocation /usr/bin/xauth
ciphers chacha20-poly1305@openssh.com,aes128-ctr,aes192-ctr,aes256-ctr,aes128-gcm@openssh.com,aes256-gcm@openssh.com
macs umac-64-etm@openssh.com,umac-128-etm@openssh.com,hmac-sha2-256-etm@openssh.com,hmac-sha2-512-etm@openssh.com,hmac-sha1-etm@openssh.com,umac-64@openssh.com,umac-128@openssh.com,hmac-sha2-256,hmac-sha2-512,hmac-sha1
banner none
forcecommand none
chrootdirectory none
trustedusercakeys none
revokedkeys none
authorizedprincipalsfile none
versionaddendum none
authorizedkeyscommand none
authorizedkeyscommanduser none
authorizedprincipalscommand none
authorizedprincipalscommanduser none
hostkeyagent none
kexalgorithms curve25519-sha256,curve25519-sha256@libssh.org,ecdh-sha2-nistp256,ecdh-sha2-nistp384,ecdh-sha2-nistp521,diffie-hellman-group-exchange-sha256,diffie-hellman-group16-sha512,diffie-hellman-group18-sha512,diffie-hellman-group14-sha256,diffie-hellman-group14-sha1
casignaturealgorithms ecdsa-sha2-nistp256,ecdsa-sha2-nistp384,ecdsa-sha2-nistp521,ssh-ed25519,rsa-sha2-512,rsa-sha2-256,ssh-rsa
hostbasedacceptedkeytypes ecdsa-sha2-nistp256-cert-v01@openssh.com,ecdsa-sha2-nistp384-cert-v01@openssh.com,ecdsa-sha2-nistp521-cert-v01@openssh.com,ssh-ed25519-cert-v01@openssh.com,rsa-sha2-512-cert-v01@openssh.com,rsa-sha2-256-cert-v01@openssh.com,ssh-rsa-cert-v01@openssh.com,ecdsa-sha2-nistp256,ecdsa-sha2-nistp384,ecdsa-sha2-nistp521,ssh-ed25519,rsa-sha2-512,rsa-sha2-256,ssh-rsa
hostkeyalgorithms ecdsa-sha2-nistp256-cert-v01@openssh.com,ecdsa-sha2-nistp384-cert-v01@openssh.com,ecdsa-sha2-nistp521-cert-v01@openssh.com,ssh-ed25519-cert-v01@openssh.com,rsa-sha2-512-cert-v01@openssh.com,rsa-sha2-256-cert-v01@openssh.com,ssh-rsa-cert-v01@openssh.com,ecdsa-sha2-nistp256,ecdsa-sha2-nistp384,ecdsa-sha2-nistp521,ssh-ed25519,rsa-sha2-512,rsa-sha2-256,ssh-rsa
pubkeyacceptedkeytypes ecdsa-sha2-nistp256-cert-v01@openssh.com,ecdsa-sha2-nistp384-cert-v01@openssh.com,ecdsa-sha2-nistp521-cert-v01@openssh.com,ssh-ed25519-cert-v01@openssh.com,rsa-sha2-512-cert-v01@openssh.com,rsa-sha2-256-cert-v01@openssh.com,ssh-rsa-cert-v01@openssh.com,ecdsa-sha2-nistp256,ecdsa-sha2-nistp384,ecdsa-sha2-nistp521,ssh-ed25519,rsa-sha2-512,rsa-sha2-256,ssh-rsa
loglevel INFO
syslogfacility AUTHPRIV
authorizedkeysfile .ssh/authorized_keys
hostkey /etc/ssh/ssh_host_rsa_key
hostkey /etc/ssh/ssh_host_ecdsa_key
hostkey /etc/ssh/ssh_host_ed25519_key
acceptenv LANG
acceptenv LC_CTYPE
acceptenv LC_NUMERIC
acceptenv LC_TIME
acceptenv LC_COLLATE
acceptenv LC_MONETARY
acceptenv LC_MESSAGES
acceptenv LC_PAPER
acceptenv LC_NAME
acceptenv LC_ADDRESS
acceptenv LC_TELEPHONE
acceptenv LC_MEASUREMENT
acceptenv LC_IDENTIFICATION
acceptenv LC_ALL
acceptenv LANGUAGE
acceptenv XMODIFIERS
authenticationmethods any
subsystem sftp internal-sftp
maxstartups 10:30:100
permittunnel no
ipqos af21 cs1
rekeylimit 0 0
permitopen any
permitlisten any
permituserenvironment no
```

# テスト成功しました