1.首先打开debug，看看慢在哪里
[root@BC-NFS1 ~]# ssh -v root@192.168.102.41 -p 22 OpenSSH_6.6.1, OpenSSL 1.0.1e-fips 11 Feb 2013 debug1: Reading configuration data /etc/ssh/ssh_config debug1: /etc/ssh/ssh_config line 56: Applying options for * debug1: Connecting to 192.168.102.41 [192.168.102.41] port 22. debug1: Connection established. debug1: permanently_set_uid: 0/0 debug1: identity file /root/.ssh/id_rsa type 1 debug1: identity file /root/.ssh/id_rsa-cert type -1 debug1: identity file /root/.ssh/id_dsa type -1 debug1: identity file /root/.ssh/id_dsa-cert type -1 debug1: identity file /root/.ssh/id_ecdsa type -1 debug1: identity file /root/.ssh/id_ecdsa-cert type -1 debug1: identity file /root/.ssh/id_ed25519 type -1 debug1: identity file /root/.ssh/id_ed25519-cert type -1 debug1: Enabling compatibility mode for protocol 2.0 debug1: Local version string SSH-2.0-OpenSSH_6.6.1 debug1: Remote protocol version 2.0, remote software version OpenSSH_6.6.1 debug1: match: OpenSSH_6.6.1 pat OpenSSH_6.6.1* compat 0x04000000 debug1: SSH2_MSG_KEXINIT sent debug1: SSH2_MSG_KEXINIT received debug1: kex: server->client aes128-ctr hmac-md5-etm@openssh.com none debug1: kex: client->server aes128-ctr hmac-md5-etm@openssh.com none debug1: kex: curve25519-sha256@libssh.org need=16 dh_need=16 debug1: kex: curve25519-sha256@libssh.org need=16 dh_need=16 debug1: sending SSH2_MSG_KEX_ECDH_INIT debug1: expecting SSH2_MSG_KEX_ECDH_REPLY debug1: Server host key: ECDSA 52:28:48:e7:49:2a:c3:56:78:c1:ea:78:58:56:ab:27 debug1: Host '192.168.102.41' is known and matches the ECDSA host key. debug1: Found key in /root/.ssh/known_hosts:2 debug1: ssh_ecdsa_verify: signature correct debug1: SSH2_MSG_NEWKEYS sent debug1: expecting SSH2_MSG_NEWKEYS debug1: SSH2_MSG_NEWKEYS received debug1: Roaming not allowed by server debug1: SSH2_MSG_SERVICE_REQUEST sent debug1: SSH2_MSG_SERVICE_ACCEPT received debug1: Authentications that can continue: publickey,gssapi-keyex,gssapi-with-mic,password debug1: Next authentication method: gssapi-keyex debug1: No valid Key exchange context debug1: Next authentication method: gssapi-with-mic debug1: Unspecified GSS failure. Minor code may provide more information No Kerberos credentials available (default cache: FILE:/tmp/krb5cc_0) debug1: Unspecified GSS failure. Minor code may provide more information No Kerberos credentials available (default cache: FILE:/tmp/krb5cc_0) debug1: Next authentication method: publickey debug1: Offering RSA public key: /root/.ssh/id_rsa debug1: Authentications that can continue: publickey,gssapi-keyex,gssapi-with-mic,password debug1: Trying private key: /root/.ssh/id_dsa debug1: Trying private key: /root/.ssh/id_ecdsa debug1: Trying private key: /root/.ssh/id_ed25519 debug1: Next authentication method: password root@192.168.102.41's password:
2.修改配置文件
在被远程登录的服务器上执行以下操作
vi /etc/ssh/sshd_config UseDNS no
看到我的debug信息有这些，说明还需要修改/etc/ssh/sshd_config
debug1: Next authentication method: gssapi-with-mic debug1: Unspecified GSS failure. Minor code may provide more information
vi /etc/ssh/ssh_config GSSAPIAuthentication no
3.重启服务
systemctl restart sshd
有的人的问题出在输入密码之后要等待10-20s
root@x.x.x.x's password: debug1: Authentication succeeded (password). Authenticated to x.x.x.x ([x.x.x.x]:xx). debug1: channel 0: new [client-session] debug1: Requesting no-more-sessions@openssh.com debug1: Entering interactive session.
通过日志可以发现，密码的验证没有损耗时间，已经正确验证通过Authentication succeeded (password)
哪么到底是什么原因导致的速度这么慢？
打开服务器的系统日志，查看
tail -f /var/log/auth.log sshd[12642]: pam_systemd(sshd:session): Failed to create session: Connection timed out dbus[617]: [system] Failed to activate service 'org.freedesktop.login1': timed out sshd[12642]: Received disconnect from x.x.x.x port 52856:11: disconnected by user sshd[12642]: Disconnected from x.x.x.x port 52856 sshd[12642]: pam_unix(sshd:session): session closed for user root sshd[12689]: userauth_pubkey: key type ssh-dss not in PubkeyAcceptedKeyTypes [preauth] sshd[12689]: Accepted password for root from x.x.x.x port 52866 ssh2 sshd[12689]: pam_unix(sshd:session): session opened for user root by (uid=0) sshd[12689]: pam_systemd(sshd:session): Failed to create session: Connection timed out dbus[617]: [system] Failed to activate service 'org.freedesktop.login1': timed out
从日志中可以看到[system] Failed to activate service 'org.freedesktop.login1': timed out
的错误，查了下资料，大致意思如下：
dbus的服务重启后，systemd-logind服务没有重启导致，可以查看systemctl status systemd-logind的状态，解决方法就是重启该服务 systemctl restart systemd-logind
重启systemd-logind服务后，发现ssh可以秒连接了