1.本机ip信息
# 配置 允许那些服务器可以ssh连接本机 服务器 [root@centos-test ~]# ifconfig eth0 eth0: flags=4163<UP,BROADCAST,RUNNING,MULTICAST> mtu 1500 inet 192.168.56.30 netmask 255.255.255.0 broadcast 192.168.56.255 inet6 fe80::20c:29ff:fe37:bb34 prefixlen 64 scopeid 0x20<link> ether 00:0c:29:37:bb:34 txqueuelen 1000 (Ethernet) RX packets 773269 bytes 1067575861 (1018.1 MiB) RX errors 0 dropped 0 overruns 0 frame 0 TX packets 216881 bytes 21516022 (20.5 MiB) TX errors 0 dropped 0 overruns 0 carrier 0 collisions 0 # 测试ssh连接centos-test 服务器 [root@test ~]# ifconfig eth0 eth0: flags=4163<UP,BROADCAST,RUNNING,MULTICAST> mtu 1500 inet 192.168.56.29 netmask 255.255.255.0 broadcast 192.168.56.255 inet6 fe80::20c:29ff:fe4d:2d9 prefixlen 64 scopeid 0x20<link> ether 00:0c:29:4d:02:d9 txqueuelen 1000 (Ethernet) RX packets 80809 bytes 59858430 (57.0 MiB) RX errors 0 dropped 0 overruns 0 frame 0 TX packets 58786 bytes 6633500 (6.3 MiB) TX errors 0 dropped 0 overruns 0 carrier 0 collisions 0
2.禁止root用户登录，并指定用户服务器登录
[root@centos-test ~]# cat /etc/ssh/sshd_config # $OpenBSD: sshd_config,v 1.100 2016/08/15 12:32:04 naddy Exp $ # This is the sshd server system-wide configuration file. See # sshd_config(5) for more information. # This sshd was compiled with PATH=/usr/local/bin:/usr/bin # The strategy used for options in the default sshd_config shipped with # OpenSSH is to specify options with their default value where # possible, but leave them commented. Uncommented options override the # default value. # If you want to change the port on a SELinux system, you have to tell # SELinux about this change. # semanage port -a -t ssh_port_t -p tcp #PORTNUMBER # #Port 22 #ListenAddress 0.0.0.0 #ListenAddress :: HostKey /etc/ssh/ssh_host_rsa_key #HostKey /etc/ssh/ssh_host_dsa_key HostKey /etc/ssh/ssh_host_ecdsa_key HostKey /etc/ssh/ssh_host_ed25519_key # Ciphers and keying #RekeyLimit default none # Logging #LogLevel INFO # Authentication: #LoginGraceTime 2m #StrictModes yes #MaxAuthTries 6 #MaxSessions 10 #PubkeyAuthentication yes # The default is to check both .ssh/authorized_keys and .ssh/authorized_keys2 # but this is overridden so installations will only check .ssh/authorized_keys AuthorizedKeysFile .ssh/authorized_keys #AuthorizedPrincipalsFile none #AuthorizedKeysCommand none #AuthorizedKeysCommandUser nobody # For this to work you will also need host keys in /etc/ssh/ssh_known_hosts #HostbasedAuthentication no # Change to yes if you don't trust ~/.ssh/known_hosts for # HostbasedAuthentication #IgnoreUserKnownHosts no # Don't read the user's ~/.rhosts and ~/.shosts files #IgnoreRhosts yes # To disable tunneled clear text passwords, change to no here! #PermitEmptyPasswords no # Change to no to disable s/key passwords #ChallengeResponseAuthentication yes ChallengeResponseAuthentication no # Kerberos options #KerberosAuthentication no #KerberosOrLocalPasswd yes #KerberosTicketCleanup yes #KerberosGetAFSToken no #KerberosUseKuserok yes # GSSAPI options GSSAPIAuthentication no GSSAPICleanupCredentials no #GSSAPIStrictAcceptorCheck yes #GSSAPIKeyExchange no #GSSAPIEnablek5users no # Set this to 'yes' to enable PAM authentication, account processing, # and session processing. If this is enabled, PAM authentication will # be allowed through the ChallengeResponseAuthentication and # PAM authentication via ChallengeResponseAuthentication may bypass # If you just want the PAM account and session checks to run without # and ChallengeResponseAuthentication to 'no'. # WARNING: 'UsePAM no' is not supported in Red Hat Enterprise Linux and may cause several # problems. UsePAM yes #AllowAgentForwarding yes #AllowTcpForwarding yes #GatewayPorts no X11Forwarding yes #X11DisplayOffset 10 #X11UseLocalhost yes #PermitTTY yes #PrintMotd yes #PrintLastLog yes #TCPKeepAlive yes #UseLogin no #UsePrivilegeSeparation sandbox #PermitUserEnvironment no #Compression delayed #ClientAliveInterval 0 #ClientAliveCountMax 3 #ShowPatchLevel no #PidFile /var/run/sshd.pid #MaxStartups 10:30:100 #PermitTunnel no #ChrootDirectory none #VersionAddendum none # no default banner path #Banner none # Accept locale-related environment variables AcceptEnv LANG LC_CTYPE LC_NUMERIC LC_TIME LC_COLLATE LC_MONETARY LC_MESSAGES AcceptEnv LC_PAPER LC_NAME LC_ADDRESS LC_TELEPHONE LC_MEASUREMENT AcceptEnv LC_IDENTIFICATION LC_ALL LANGUAGE AcceptEnv XMODIFIERS # override default of no subsystems Subsystem sftp /usr/libexec/openssh/sftp-server # Example of overriding settings on a per-user basis #Match User anoncvs # X11Forwarding no # AllowTcpForwarding no # PermitTTY no # ForceCommand cvs server
UseDNS no AddressFamily inet PermitRootLogin yes SyslogFacility AUTHPRIV PasswordAuthentication yes AllowUsers root@192.168.56.30 test@192.168.56.29
3.参数注释
GSSAPIAuthentication no: 是否允许使用基于 GSSAPI 的用户认证。默认值为"no"。仅用于SSH-2【关闭GSSAPI用户认证，优化ssh连接速度】
UseDNS no：OpenSSH在用户登录的时候会验证IP，它根据用户的IP使用反向DNS找到主机名，再使用DNS找到IP地址，最后匹配一下登录的IP是否合法。如果客户机的IP没有域名，或者DNS服务器很慢或
不通，那么登录就会很花时间【关闭 SSH 的 DNS 反解析，优化ssh连接速度】
PermitRootLogin yes：允许root用户登录【PermitRootLogin no # 禁止root用户远程登录】
PasswordAuthentication yes：开启基于密码认证的远程登录
AllowUsers ：允许192.168.56.30地址的root用户登录本机/允许全部192.168.56.29的test用户登录本机。
4.重启centos-test服务器sshd，测试链接
[root@centos-test ~]# systemctl restart sshd
[root@test ~]# ssh root@192.168.56.30 root@192.168.56.30's password: Permission denied, please try again.
[root@test ~]# ssh test@192.168.56.30 test@192.168.56.30's password: Last login: Sun Sep 27 15:30:10 2020 from 192.168.56.28 [test@centos7 ~]$
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