centos下SSH 登陆变慢的解决方法

发布时间:2019-09-19编辑:脚本学堂
本文介绍下,在centos系统中遇到ssh登录慢的问题的解决方法,有需要的朋友参考下。

首先,查看登录信息:
 

WaveMac:~ zlpx$ ssh -vvv root@wavehome 
OpenSSH_5.9p1, OpenSSL 0.9.8y 5 Feb 2013 
debug1: Reading configuration data /etc/ssh_config 
debug1: /etc/ssh_config line 20: Applying options for * 
debug2: ssh_connect: needpriv 0 
debug1: Connecting to wavehome [192.168.1.111] port 22. 
debug1: Connection established. 
debug1: identity file /Users/zlpx/.ssh/id_rsa type -1 
debug1: identity file /Users/zlpx/.ssh/id_rsa-cert type -1 
debug1: identity file /Users/zlpx/.ssh/id_dsa type -1 
debug1: identity file /Users/zlpx/.ssh/id_dsa-cert type -1 
debug1: Remote protocol version 2.0, remote software version OpenSSH_5.3 
debug1: match: OpenSSH_5.3 pat OpenSSH* 
debug1: Enabling compatibility mode for protocol 2.0 
debug1: Local version string SSH-2.0-OpenSSH_5.9 
debug2: fd 3 setting O_NONBLOCK 
debug3: load_hostkeys: loading entries for host "wavehome" from file "/Users/zlpx/.ssh/known_hosts" 
debug3: load_hostkeys: found key type RSA in file /Users/zlpx/.ssh/known_hosts:2 
debug3: load_hostkeys: loaded 1 keys 
debug3: order_hostkeyalgs: prefer hostkeyalgs: root@jbxue@openssh.com,ssh-rsa-cert-v00@openssh.com,ssh-rsa 
debug1: SSH2_MSG_KEXINIT sent 
debug1: SSH2_MSG_KEXINIT received 
debug2: kex_parse_kexinit: diffie-hellman-group-exchange-sha256,diffie-hellman-group-exchange-sha1,diffie-hellman-group14-sha1,diffie-hellman-group1-sha1 
debug2: kex_parse_kexinit: root@jbxue@openssh.com,ssh-rsa-cert-v00@openssh.com,ssh-rsa,ssh-dss-cert-v01@openssh.com,ssh-dss-cert-v00@openssh.com,ssh-dss 
debug2: kex_parse_kexinit: aes128-ctr,aes192-ctr,aes256-ctr,arcfour256,arcfour128,aes128-cbc,3des-cbc,blowfish-cbc,cast128-cbc,aes192-cbc,aes256-cbc,arcfour,rijndael-cbc@lysator.liu.se 
debug2: kex_parse_kexinit: aes128-ctr,aes192-ctr,aes256-ctr,arcfour256,arcfour128,aes128-cbc,3des-cbc,blowfish-cbc,cast128-cbc,aes192-cbc,aes256-cbc,arcfour,rijndael-cbc@lysator.liu.se 
debug2: kex_parse_kexinit: hmac-md5,hmac-sha1,umac-64@openssh.com,hmac-sha2-256,hmac-sha2-256-96,hmac-sha2-512,hmac-sha2-512-96,hmac-ripemd160,hmac-ripemd160@openssh.com,hmac-sha1-96,hmac-md5-96 
debug2: kex_parse_kexinit: hmac-md5,hmac-sha1,umac-64@openssh.com,hmac-sha2-256,hmac-sha2-256-96,hmac-sha2-512,hmac-sha2-512-96,hmac-ripemd160,hmac-ripemd160@openssh.com,hmac-sha1-96,hmac-md5-96 
debug2: kex_parse_kexinit: none,zlib@openssh.com,zlib 
debug2: kex_parse_kexinit: none,zlib@openssh.com,zlib 
debug2: kex_parse_kexinit:  
debug2: kex_parse_kexinit:  
debug2: kex_parse_kexinit: first_kex_follows 0  
debug2: kex_parse_kexinit: reserved 0  
debug2: kex_parse_kexinit: diffie-hellman-group-exchange-sha256,diffie-hellman-group-exchange-sha1,diffie-hellman-group14-sha1,diffie-hellman-group1-sha1 
debug2: kex_parse_kexinit: ssh-rsa,ssh-dss 
debug2: kex_parse_kexinit: aes128-ctr,aes192-ctr,aes256-ctr,arcfour256,arcfour128,aes128-cbc,3des-cbc,blowfish-cbc,cast128-cbc,aes192-cbc,aes256-cbc,arcfour,rijndael-cbc@lysator.liu.se 
debug2: kex_parse_kexinit: aes128-ctr,aes192-ctr,aes256-ctr,arcfour256,arcfour128,aes128-cbc,3des-cbc,blowfish-cbc,cast128-cbc,aes192-cbc,aes256-cbc,arcfour,rijndael-cbc@lysator.liu.se 
debug2: kex_parse_kexinit: hmac-md5,hmac-sha1,umac-64@openssh.com,hmac-ripemd160,hmac-ripemd160@openssh.com,hmac-sha1-96,hmac-md5-96 
debug2: kex_parse_kexinit: hmac-md5,hmac-sha1,umac-64@openssh.com,hmac-ripemd160,hmac-ripemd160@openssh.com,hmac-sha1-96,hmac-md5-96 
debug2: kex_parse_kexinit: none,zlib@openssh.com 
debug2: kex_parse_kexinit: none,zlib@openssh.com 
debug2: kex_parse_kexinit:  
debug2: kex_parse_kexinit:  
debug2: kex_parse_kexinit: first_kex_follows 0  
debug2: kex_parse_kexinit: reserved 0  
debug2: mac_setup: found hmac-md5 
debug1: kex: server->client aes128-ctr hmac-md5 none 
debug2: mac_setup: found hmac-md5 
debug1: kex: client->server aes128-ctr hmac-md5 none 
debug1: SSH2_MSG_KEX_DH_GEX_REQUEST(1024<1024<8192) sent 
debug1: expecting SSH2_MSG_KEX_DH_GEX_GROUP 
debug2: dh_gen_key: priv key bits set: 135/256 
debug2: bits set: 506/1024 
debug1: SSH2_MSG_KEX_DH_GEX_INIT sent 
debug1: expecting SSH2_MSG_KEX_DH_GEX_REPLY 
debug1: Server host key: RSA 34:60:80:85:6d:fb:5b:d7:cb:88:bd:6f:5f:b7:52:37 
debug3: load_hostkeys: loading entries for host "wavehome" from file "/Users/zlpx/.ssh/known_hosts" 
debug3: load_hostkeys: found key type RSA in file /Users/zlpx/.ssh/known_hosts:2 
debug3: load_hostkeys: loaded 1 keys 
debug3: load_hostkeys: loading entries for host "192.168.1.111" from file "/Users/zlpx/.ssh/known_hosts" 
debug3: load_hostkeys: found key type RSA in file /Users/zlpx/.ssh/known_hosts:1 
debug3: load_hostkeys: loaded 1 keys 
debug1: Host 'wavehome' is known and matches the RSA host key. 
debug1: Found key in /Users/zlpx/.ssh/known_hosts:2 
debug2: bits set: 523/1024 
debug1: ssh_rsa_verify: signature correct 
debug2: kex_derive_keys 
debug2: set_newkeys: mode 1 
debug1: SSH2_MSG_NEWKEYS sent 
debug1: expecting SSH2_MSG_NEWKEYS 
debug2: set_newkeys: mode 0 
debug1: SSH2_MSG_NEWKEYS received 
debug1: Roaming not allowed by server 
debug1: SSH2_MSG_SERVICE_REQUEST sent 
debug2: service_accept: ssh-userauth 
debug1: SSH2_MSG_SERVICE_ACCEPT received 
debug2: key: /Users/zlpx/.ssh/id_rsa (0x0) 
debug2: key: /Users/zlpx/.ssh/id_dsa (0x0) 
debug1: Authentications that can continue: publickey,gssapi-keyex,gssapi-with-mic,password 
debug3: start over, passed a different list publickey,gssapi-keyex,gssapi-with-mic,password 
debug3: preferred publickey,keyboard-interactive,password 
debug3: authmethod_lookup publickey 
debug3: remaining preferred: keyboard-interactive,password 
debug3: authmethod_is_enabled publickey 
debug1: Next authentication method: publickey 
debug1: Trying private key: /Users/zlpx/.ssh/id_rsa 
debug3: no such identity: /Users/zlpx/.ssh/id_rsa 
debug1: Trying private key: /Users/zlpx/.ssh/id_dsa 
debug3: no such identity: /Users/zlpx/.ssh/id_dsa 
debug2: we did not send a packet, disable method 
debug3: authmethod_lookup password 
debug3: remaining preferred: ,password 
debug3: authmethod_is_enabled password 
debug1: Next authentication method: password 
root@wavehome's password:  

由以上可以看出:
登陆卡在下面两句之间:
 

debug2: key: /Users/zlpx/.ssh/id_dsa (0x0)
debug1: Authentications that can continue: publickey,gssapi-keyex,gssapi-with-mic,password

原因分析:
由于机器环境没有DNS,进一步检查,去/etc/ssh下把sshd_config 文件中,把 UseDNS no 设置上,禁止使用DNS解析,登录恢复正常。