我的全新的centos服务器openssh有一些麻烦。 有时在10秒钟之后，有时在2-3分钟之后，壳冻结。 （通过主机closures连接）当shell冻结时，我不能再次login大约10分钟。
我尝试了所有经典解决scheme，例如启用KeepAlive时间间隔，禁用DNS以及禁用GSSAPIAuthentication。
SELinux和iptables被禁用。
/ var / log / secure的最后一行：
Nov 17 04:33:07 tp sshd[2152]: Received disconnect from 194.190.136.163: 11: Bye Bye Nov 17 04:33:07 tp sshd[2153]: pam_unix(sshd:auth): authentication failure; logname= uid=0 euid=0 tty=ssh ruser= rhost=194.190.136.163 user=root Nov 17 04:33:09 tp sshd[2153]: Failed password for root from 194.190.136.163 port 48488 ssh2 Nov 17 04:33:09 tp sshd[2154]: Received disconnect from 194.190.136.163: 11: Bye Bye Nov 17 04:33:10 tp sshd[2155]: pam_unix(sshd:auth): authentication failure; logname= uid=0 euid=0 tty=ssh ruser= rhost=194.190.136.163 user=root Nov 17 04:33:12 tp sshd[2155]: Failed password for root from 194.190.136.163 port 48737 ssh2 Nov 17 10:35:37 tp sshd[2299]: Accepted password for root from 37.221.161.234 port 47783 ssh2 Nov 17 10:35:37 tp sshd[2299]: pam_unix(sshd:session): session opened for user root by (uid=0) ssh -vvv之后的debugging：
OpenSSH_6.1p1, OpenSSL 1.0.0-fips 29 Mar 2010 debug1: Reading configuration data /etc/ssh/ssh_config debug1: /etc/ssh/ssh_config line 51: Applying options for * debug2: ssh_connect: needpriv 0 debug1: Connecting to ipserver [ipserver] port 22. debug1: Connection established. debug1: identity file /home/masufasu/.ssh/id_rsa type -1 debug1: identity file /home/masufasu/.ssh/id_rsa-cert type -1 debug1: identity file /home/masufasu/.ssh/id_dsa type -1 debug1: identity file /home/masufasu/.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_5* debug1: Enabling compatibility mode for protocol 2.0 debug1: Local version string SSH-2.0-OpenSSH_6.1 debug2: fd 3 setting O_NONBLOCK debug3: load_hostkeys: loading entries for host "ipserver" from file "/home/masufasu/.ssh/known_hosts" debug3: load_hostkeys: found key type RSA in file /home/masufasu/.ssh/known_hosts:5 debug3: load_hostkeys: loaded 1 keys debug3: order_hostkeyalgs: prefer hostkeyalgs: [email protected],[email protected],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: [email protected],[email protected],ssh-rsa,[email protected],[email protected],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,[email protected] 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,[email protected] debug2: kex_parse_kexinit: hmac-md5,hmac-sha1,[email protected],hmac-sha2-256,hmac-sha2-512,hmac-ripemd160,[email protected],hmac-sha1-96,hmac-md5-96 debug2: kex_parse_kexinit: hmac-md5,hmac-sha1,[email protected],hmac-sha2-256,hmac-sha2-512,hmac-ripemd160,[email protected],hmac-sha1-96,hmac-md5-96 debug2: kex_parse_kexinit: none,[email protected],zlib debug2: kex_parse_kexinit: none,[email protected],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,[email protected] 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,[email protected] debug2: kex_parse_kexinit: hmac-md5,hmac-sha1,[email protected],hmac-ripemd160,[email protected],hmac-sha1-96,hmac-md5-96 debug2: kex_parse_kexinit: hmac-md5,hmac-sha1,[email protected],hmac-ripemd160,[email protected],hmac-sha1-96,hmac-md5-96 debug2: kex_parse_kexinit: none,[email protected] debug2: kex_parse_kexinit: none,[email protected] 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: 128/256 debug2: bits set: 473/1024 debug1: SSH2_MSG_KEX_DH_GEX_INIT sent debug1: expecting SSH2_MSG_KEX_DH_GEX_REPLY debug1: Server host key: RSA cf:f9:ec:46:7d:61:78:ec:ff:b3:c4:a6:1f:42:f0:ea debug3: load_hostkeys: loading entries for host "ipserver" from file "/home/masufasu/.ssh/known_hosts" debug3: load_hostkeys: found key type RSA in file /home/masufasu/.ssh/known_hosts:5 debug3: load_hostkeys: loaded 1 keys debug1: Host 'ipserver' is known and matches the RSA host key. debug1: Found key in /home/masufasu/.ssh/known_hosts:5 debug2: bits set: 495/1024 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: /home/masufasu/.ssh/id_rsa ((nil)) debug2: key: /home/masufasu/.ssh/id_dsa ((nil)) debug1: Authentications that can continue: publickey,password debug3: start over, passed a different list publickey,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: /home/masufasu/.ssh/id_rsa debug3: no such identity: /home/masufasu/.ssh/id_rsa debug1: Trying private key: /home/masufasu/.ssh/id_dsa debug3: no such identity: /home/masufasu/.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 debug3: packet_send2: adding 64 (len 60 padlen 4 extra_pad 64) debug2: we sent a password packet, wait for reply debug1: Authentication succeeded (password). Authenticated to ipserver ([ipserver]:22). debug2: fd 5 setting O_NONBLOCK debug3: fd 6 is O_NONBLOCK debug1: channel 0: new [client-session] debug3: ssh_session2_open: channel_new: 0 debug2: channel 0: send open debug1: Requesting [email protected] debug1: Entering interactive session. debug2: callback start debug2: fd 3 setting TCP_NODELAY debug3: packet_set_tos: set IP_TOS 0x10 debug2: client_session2_setup: id 0 debug2: channel 0: request pty-req confirm 1 debug1: Sending environment. debug3: Ignored env XDG_VTNR debug3: Ignored env XDG_SESSION_ID debug3: Ignored env HOSTNAME debug3: Ignored env IMSETTINGS_INTEGRATE_DESKTOP debug3: Ignored env GPG_AGENT_INFO debug3: Ignored env TERM debug3: Ignored env SHELL debug3: Ignored env XDG_MENU_PREFIX debug3: Ignored env HISTSIZE debug3: Ignored env XDG_SESSION_COOKIE debug3: Ignored env GJS_DEBUG_OUTPUT debug3: Ignored env WINDOWID debug3: Ignored env GNOME_KEYRING_CONTROL debug3: Ignored env QTDIR debug3: Ignored env QTINC debug3: Ignored env GJS_DEBUG_TOPICS debug3: Ignored env IMSETTINGS_MODULE debug3: Ignored env QT_GRAPHICSSYSTEM_CHECKED debug3: Ignored env USER debug3: Ignored env LS_COLORS debug3: Ignored env SSH_AUTH_SOCK debug3: Ignored env SESSION_MANAGER debug3: Ignored env USERNAME debug3: Ignored env PATH debug3: Ignored env MAIL debug3: Ignored env DESKTOP_SESSION debug3: Ignored env QT_IM_MODULE debug3: Ignored env PWD debug1: Sending env XMODIFIERS = @im=ibus debug2: channel 0: request env confirm 0 debug3: Ignored env GNOME_KEYRING_PID debug1: Sending env LANG = it_IT.UTF-8 debug2: channel 0: request env confirm 0 debug3: Ignored env KDE_IS_PRELINKED debug3: Ignored env KDEDIRS debug3: Ignored env AUTOJUMP_DATA_DIR debug3: Ignored env GDMSESSION debug3: Ignored env HISTCONTROL debug3: Ignored env KRB5CCNAME debug3: Ignored env XDG_SEAT debug3: Ignored env HOME debug3: Ignored env SHLVL debug3: Ignored env GNOME_DESKTOP_SESSION_ID debug3: Ignored env AUTOJUMP_HOME debug3: Ignored env LOGNAME debug3: Ignored env QTLIB debug3: Ignored env DBUS_SESSION_BUS_ADDRESS debug3: Ignored env LESSOPEN debug3: Ignored env PROMPT_COMMAND debug3: Ignored env WINDOWPATH debug3: Ignored env XDG_RUNTIME_DIR debug3: Ignored env DISPLAY debug3: Ignored env QT_PLUGIN_PATH debug3: Ignored env COLORTERM debug3: Ignored env XAUTHORITY debug3: Ignored env _ debug2: channel 0: request shell confirm 1 debug2: callback done debug2: channel 0: open confirm rwindow 0 rmax 32768 debug2: channel_input_status_confirm: type 99 id 0 debug2: PTY allocation request accepted on channel 0 debug2: channel 0: rcvd adjust 2097152 debug2: channel_input_status_confirm: type 99 id 0 debug2: shell request accepted on channel 0 Last login: Sat Nov 16 18:38:52 2013 from 2.237.239.68 ]0;root@tp:~[?1034h[root@tp ~]# debug1: client_input_channel_req: channel 0 rtype [email protected] reply 1 debug1: client_input_channel_req: channel 0 rtype [email protected] reply 1 debug1: client_input_channel_req: channel 0 rtype [email protected] reply 1 debug1: client_input_channel_req: channel 0 rtype [email protected] reply 1 debug1: client_input_channel_req: channel 0 rtype [email protected] reply 1 debug1: client_input_channel_req: channel 0 rtype [email protected] reply 1 debug1: client_input_channel_req: channel 0 rtype [email protected] reply 1 debug1: client_input_channel_req: channel 0 rtype [email protected] reply 1 debug1: client_input_channel_req: channel 0 rtype [email protected] reply 1 debug1: client_input_channel_req: channel 0 rtype [email protected] reply 1 debug1: client_input_channel_req: channel 0 rtype [email protected] reply 1 debug1: client_input_channel_req: channel 0 rtype [email protected] reply 1 debug1: client_input_channel_req: channel 0 rtype [email protected] reply 1 debug1: client_input_channel_req: channel 0 rtype [email protected] reply 1 debug1: client_input_channel_req: channel 0 rtype [email protected] reply 1 debug1: client_input_channel_req: channel 0 rtype [email protected] reply 1 debug1: client_input_channel_req: channel 0 rtype [email protected] reply 1 debug1: client_input_channel_req: channel 0 rtype [email protected] reply 1 debug1: client_input_channel_req: channel 0 rtype [email protected] reply 1 debug1: client_input_channel_req: channel 0 rtype [email protected] reply 1 debug1: channel 0: free: client-session, nchannels 1 debug3: channel 0: status: The following connections are open: #0 client-session (t4 r0 i0/0 o0/0 fd 4/5 cc -1) debug1: fd 1 clearing O_NONBLOCK debug3: fd 2 is not O_NONBLOCK Connection to ipserver closed by remote host. Connection to ipserver closed. Transferred: sent 2312, received 2952 bytes, in 211.2 seconds Bytes per second: sent 10.9, received 14.0 debug1: Exit status -1
netstat -lnpt | grep 22 netstat -lnpt | grep 22 ：
tcp 0 0 0.0.0.0:22 0.0.0.0:* LISTEN 1495/sshd tcp 0 0 :::22 :::* LISTEN 1495/sshd
在/ var / log / messages中
nf_conntrack version 0.5.0 (16384 buckets, 65536 max) r8169 0000:02:00.0: firmware: requesting rtl_nic/rtl8168e-3.fw r8169 0000:02:00.0: eth0: link down r8169 0000:02:00.0: eth0: link down ADDRCONF(NETDEV_UP): eth0: link is not ready r8169 0000:02:00.0: eth0: link up ADDRCONF(NETDEV_CHANGE): eth0: link becomes ready
你能够scp一个大型文件进出服务器？
如果不是，并且几乎立即开始失败，则客户端和服务器之间的pathMTU问题。
如果是这样的话，你可能会有一个过于激进的防火墙，或者在状态表中没有任何空间。 你有networking上的Bittorrent用户吗？ 该协议在状态表上可能非常困难。