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目录列表 (ls) 错误仅在端口 22 (SFTP) 中发生

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目录列表 (ls) 错误仅在端口 22 (SFTP) 中发生

使用安全FTP我突然得到这个结果：

Status: Connecting to 64.207.146.82...
Response:   fzSftp started
Command:    open "[email protected]" 22
Command:    Pass: *********
Status: Connected to 64.207.146.82
Status: Retrieving directory listing...
Command:    pwd
Response:   Current directory is: "/root"
Command:    ls
Status: Listing directory /root
Error:  Connection timed out
Error:  Failed to retrieve directory listing

我测试过网络鸭，档案文件和终端，结果相同。我可以登录，但是一旦我到达以下位置：目录列表它冻结了（没有答案）。

我可以使用 FTP 访问（端口 21)，问题是我无法更新任何文件（我一直以 root 身份工作）。

在 3 台电脑上测试，结果与我办公室的相同。但是，我在家里测试，它工作正常（所以我猜不是托管提供商的问题）。

从 ssh 进行一些调试：

ssh -vv [email protected]
OpenSSH_5.6p1, OpenSSL 0.9.8r 8 Feb 2011
debug1: Reading configuration data /etc/ssh_config
debug1: Applying options for *
debug2: ssh_connect: needpriv 0
debug1: Connecting to domain.com [64.207.146.82] port 22.
debug1: Connection established.
debug1: identity file /Users/Admin/.ssh/id_rsa type -1
debug1: identity file /Users/Admin/.ssh/id_rsa-cert type -1
debug1: identity file /Users/Admin/.ssh/id_dsa type -1
debug1: identity file /Users/Admin/.ssh/id_dsa-cert type -1
debug1: Remote protocol version 2.0, remote software version OpenSSH_4.3
debug1: match: OpenSSH_4.3 pat OpenSSH_4*
debug1: Enabling compatibility mode for protocol 2.0
debug1: Local version string SSH-2.0-OpenSSH_5.6
debug2: fd 3 setting O_NONBLOCK
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],[email protected],[email protected],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],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-sha1,diffie-hellman-group14-sha1,diffie-hellman-group1-sha1
debug2: kex_parse_kexinit: ssh-rsa,ssh-dss
debug2: kex_parse_kexinit: aes128-cbc,3des-cbc,blowfish-cbc,cast128-cbc,arcfour128,arcfour256,arcfour,aes192-cbc,aes256-cbc,[email protected],aes128-ctr,aes192-ctr,aes256-ctr
debug2: kex_parse_kexinit: aes128-cbc,3des-cbc,blowfish-cbc,cast128-cbc,arcfour128,arcfour256,arcfour,aes192-cbc,aes256-cbc,[email protected],aes128-ctr,aes192-ctr,aes256-ctr
debug2: kex_parse_kexinit: hmac-md5,hmac-sha1,hmac-ripemd160,[email protected],hmac-sha1-96,hmac-md5-96
debug2: kex_parse_kexinit: hmac-md5,hmac-sha1,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: 543/1024
debug1: SSH2_MSG_KEX_DH_GEX_INIT sent
debug1: expecting SSH2_MSG_KEX_DH_GEX_REPLY
debug1: Host 'domain.com' is known and matches the RSA host key.
debug1: Found key in /Users/Admin/.ssh/known_hosts:2
debug2: bits set: 508/1024
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/Admin/.ssh/id_rsa (0x0)
debug2: key: /Users/Admin/.ssh/id_dsa (0x0)
debug1: Authentications that can continue: publickey,gssapi-with-mic,password
debug1: Next authentication method: publickey
debug1: Trying private key: /Users/Admin/.ssh/id_rsa
debug1: Trying private key: /Users/Admin/.ssh/id_dsa
debug2: we did not send a packet, disable method
debug1: Next authentication method: password
[email protected]'s password: 
debug2: we sent a password packet, wait for reply
debug1: Authentication succeeded (password).
Authenticated to domain.com ([64.207.146.82]:22).
debug1: channel 0: new [client-session]
debug2: channel 0: send open
debug1: Entering interactive session.
debug2: callback start
debug2: client_session2_setup: id 0
debug2: channel 0: request pty-req confirm 1
debug1: Sending environment.
debug1: Sending env LANG = en_US.UTF-8
debug2: channel 0: request env confirm 0
debug2: channel 0: request shell confirm 1
debug2: fd 3 setting TCP_NODELAY
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: Fri Dec 21 19:55:45 2012 from ip5-222-15-186.ct.co.cr
############################################################
                     (mt) shortcuts
############################################################

To see your Plesk password, type: p

To rebuild your Apache/Web Server configuration, type: web

To rebuild your Qmail/Mail Server configuration, type: mchk

To see your Qmail/Mail Server queue, type: q

To completely restart your Qmail/Mail server, type: r

To connect to your MySQL server as admin, type: my

To apply the latest Plesk microupdates, type: up

To get rid of these messages/aliases, edit your /root/.bash_profile

[root@domain ~]#

解决方案：

一旦您使用 SSH 登录/连接服务器：

p link show
1: lo: <LOOPBACK,UP,LOWER_UP> mtu 16436 qdisc noqueue 
    link/loopback 00:00:00:00:00:00 brd 00:00:00:00:00:00
3: venet0: <BROADCAST,POINTOPOINT,NOARP,UP,LOWER_UP> mtu 1500 qdisc noqueue 
    link/void 
[root@domian ~]# ip link set eth0 mtu 1400
SIOCSIFMTU: No such device
[root@domian ~]# ip link set venet0 mtu 1400
[root@domian ~]# ip link show
1: lo: <LOOPBACK,UP,LOWER_UP> mtu 16436 qdisc noqueue 
    link/loopback 00:00:00:00:00:00 brd 00:00:00:00:00:00
3: venet0: <BROADCAST,POINTOPOINT,NOARP,UP,LOWER_UP> mtu 1400 qdisc noqueue 
    link/void 
[root@domian ~]#

答案1

您的网络是否采用 PPPoE 连接？如果您尝试使用 scp 下载大型文件（超过 1 千字节），是否也会遇到此问题？

如果是这样，那么看起来你可能遇到了 MTU 大小问题。这是 DSL 网络的常见问题，如果你在 Google 上搜索“pppoe mtu”，你会找到很多结果。例如，思科有一个相当好的解释。

简而言之，当客户端和服务器协商最大 MTU 大小时，它们会根据它们自己的直接连接（通常是 LAN）进行协商，当它们之间存在最大允许 MTU 大小较小的链接（PPPoE 链接）时，较大的数据包会开始丢失。

通常可以通过以下方法解决：

iptables -t mangle -A POSTROUTING -o ppp+ \
    -p tcp -m tcp --tcp-flags SYN,RST SYN \
    -j TCPMSS --clamp-mss-to-pmtu

更新：由于看起来似乎没有任何 PPP 连接，您可以尝试降低服务器上的接口 MTU 以进行测试，这样您就知道问题是否出在这里。例如，您可以使用以下命令检查当前值：

ip link show

在输出中查找“MTU”。然后暂时地降低它（假设eth0是你的界面），尝试

ip link set eth0 mtu 1400

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