Sec*_*hel 5 ssh file-transfer sftp perl
概述
我正在现场在 Windows 7 机器上编写 SFTP 文件传输脚本。当我传输大于 1 兆字节左右的 zip 文件时，传输（和 SSH）在大约 700KB 后意外停止。SSH 进程似乎挂起，但它并没有开始大量消耗 CPU 或内存，Windows 也没有说它已停止响应。服务器最终放弃并超时，但客户端永远不会返回（尽管设置了 ServerAliveCountMax 和 ServerAliveInterval）。服务器日志显示传输开始，然后超时并在很长时间后断开连接。
细节
背靠背重新运行脚本，每次挂起前传输相同数量的字节。走开再回来，然后再次运行脚本，字节数会相差几十千字节。
命令行 sftp.exe 客户端使用默认选项正常工作；那些较大的 zip 文件传输成功。我无法测试 scp.exe，因为 SSH 用户帐户没有外壳访问权限。我相信问题在操作系统擦除和从 XP 到 7 的重新映像中仍然存在，所以我怀疑是网络问题，但我无法理解什么样的问题会导致这种行为。
我正在使用 Perl 和 Net::SFTP::Foreign 模块编写脚本。以下是从我的测试用例脚本中提取的相关代码（下面附有 SSH 输出日志）：
my %connectOpts = (
user => $username
,timeout => $timeout
,warn => sub {}
,more => [ "-o PreferredAuthentications=publickey",
"-o ServerAliveCountMax=6",
"-o ServerAliveInterval=" . int($timeout/6),
"-vvvv" ]
);
my $sftp = Net::SFTP::Foreign::Compat->new( $host, %connectOpts );
foreach my $local_file ( @local_files ) {
$sftp->do_stat( 'upload.tmp' ) && print( "Overwriting upload.tmp\n" );
$sftp->put( $local_file, 'upload.tmp' );
$sftp->do_rename( 'upload.tmp', basename( $local_file ));
}
出于相同的目的，我在数十台其他现场 PC 上使用此代码和非常相似的配置。这是我第一次看到这个问题。我正在寻找根本原因或诊断建议，而不是该生态系统之外的解决方法。有无数种方法可以编写此脚本，但我需要 Net::SFTP::Foreign 模块的粒度、反馈和模块化来进行日志记录和错误报告。Perl 是唯一可用的脚本语言。
谢谢。这令人非常沮丧。
配置：
客户端输出（-vvvv），直到我手动终止 ssh.exe 后它横盘整理：
OpenSSH_5.3p1, OpenSSL 0.9.8k 25 Mar 2009
debug1: Reading configuration data /etc/ssh_config
debug2: ssh_connect: needpriv 0
debug1: Connecting to sftp.server.com [xx.xx.xx.xx] port 22.
debug1: Connection established.
debug1: identity file /cygdrive/c/program files/copssh/.ssh/identity type -1
debug3: Not a RSA1 key file /cygdrive/c/program files/copssh/.ssh/id_rsa.
debug2: key_type_from_name: unknown key type '-----BEGIN'
debug3: key_read: missing keytype
debug3: key_read: missing whitespace
debug3: key_read: missing whitespace
debug3: key_read: missing whitespace
debug3: key_read: missing whitespace
debug3: key_read: missing whitespace
debug3: key_read: missing whitespace
debug3: key_read: missing whitespace
debug3: key_read: missing whitespace
debug3: key_read: missing whitespace
debug3: key_read: missing whitespace
debug3: key_read: missing whitespace
debug3: key_read: missing whitespace
debug3: key_read: missing whitespace
debug3: key_read: missing whitespace
debug3: key_read: missing whitespace
debug3: key_read: missing whitespace
debug3: key_read: missing whitespace
debug3: key_read: missing whitespace
debug3: key_read: missing whitespace
debug3: key_read: missing whitespace
debug3: key_read: missing whitespace
debug3: key_read: missing whitespace
debug3: key_read: missing whitespace
debug3: key_read: missing whitespace
debug3: key_read: missing whitespace
debug2: key_type_from_name: unknown key type '-----END'
debug3: key_read: missing keytype
debug1: identity file /cygdrive/c/program files/copssh/.ssh/id_rsa type 1
debug1: identity file /cygdrive/c/program files/copssh/.ssh/id_dsa type -1
debug1: Remote protocol version 2.0, remote software version 6.2.1.168 SSH Tectia Server
debug1: no match: 6.2.1.168 SSH Tectia Server
debug1: Enabling compatibility mode for protocol 2.0
debug1: Local version string SSH-2.0-OpenSSH_5.3
debug2: fd 3 setting O_NONBLOCK
debug1: SSH2_MSG_KEXINIT sent
debug3: Wrote 792 bytes for a total of 813
debug1: SSH2_MSG_KEXINIT received
debug2: kex_parse_kexinit: diffie-hellman-group-exchange-sha256,diffie-hellman-g
roup-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,arcfour12
8,aes128-cbc,3des-cbc,blowfish-cbc,cast128-cbc,aes192-cbc,aes256-cbc,arcfour,rij
ndael-cbc@lysator.liu.se
debug2: kex_parse_kexinit: aes128-ctr,aes192-ctr,aes256-ctr,arcfour256,arcfour12
8,aes128-cbc,3des-cbc,blowfish-cbc,cast128-cbc,aes192-cbc,aes256-cbc,arcfour,rij
ndael-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,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-group1-sha1,diffie-hellman-group14-sha
1,diffie-hellman-group14-sha256@ssh.com,diffie-hellman-group-exchange-sha1,diffi
e-hellman-group-exchange-sha256
debug2: kex_parse_kexinit: ssh-rsa,ssh-rsa-sha256@ssh.com
debug2: kex_parse_kexinit: aes256-cbc,aes192-cbc,aes128-cbc,3des-cbc
debug2: kex_parse_kexinit: aes256-cbc,aes192-cbc,aes128-cbc,3des-cbc
debug2: kex_parse_kexinit: hmac-sha1
debug2: kex_parse_kexinit: hmac-sha1
debug2: kex_parse_kexinit: none,zlib
debug2: kex_parse_kexinit: none,zlib
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-sha1
debug1: kex: server->client aes128-cbc hmac-sha1 none
debug2: mac_setup: found hmac-sha1
debug1: kex: client->server aes128-cbc hmac-sha1 none
debug1: SSH2_MSG_KEX_DH_GEX_REQUEST(1024<2048<8192) sent
debug1: expecting SSH2_MSG_KEX_DH_GEX_GROUP
debug3: Wrote 24 bytes for a total of 837
debug2: dh_gen_key: priv key bits set: 160/320
debug2: bits set: 1016/2048
debug1: SSH2_MSG_KEX_DH_GEX_INIT sent
debug1: expecting SSH2_MSG_KEX_DH_GEX_REPLY
debug3: Wrote 272 bytes for a total of 1109
debug3: check_host_in_hostfile: filename /cygdrive/c/program files/copssh/.ssh/known_hosts
debug3: check_host_in_hostfile: match line 2
debug3: check_host_in_hostfile: filename /cygdrive/c/program files/copssh/.ssh/known_hosts
debug3: check_host_in_hostfile: match line 1
debug1: Host 'sftp.server.com' is known and matches the RSA host key.
debug1: Found key in /cygdrive/c/program files/copssh/.ssh/known_hosts:2
debug2: bits set: 995/2048
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
debug3: Wrote 16 bytes for a total of 1125
debug2: set_newkeys: mode 0
debug1: SSH2_MSG_NEWKEYS received
debug1: SSH2_MSG_SERVICE_REQUEST sent
debug3: Wrote 52 bytes for a total of 1177
debug3: Received SSH2_MSG_IGNORE
debug3: Received SSH2_MSG_IGNORE
debug2: service_accept: ssh-userauth
debug1: SSH2_MSG_SERVICE_ACCEPT received
debug2: key: /cygdrive/c/program files/copssh/.ssh/identity (0x0)
debug2: key: /cygdrive/c/program files/copssh/.ssh/id_rsa (0xd4b720)
debug2: key: /cygdrive/c/program files/copssh/.ssh/id_dsa (0x0)
debug3: Wrote 84 bytes for a total of 1261
debug3: Received SSH2_MSG_IGNORE
debug1: Authentications that can continue: publickey,keyboard-interactive
debug3: start over, passed a different list publickey,keyboard-interactive
debug3: preferred publickey
debug3: authmethod_lookup publickey
debug3: remaining preferred:
debug3: authmethod_is_enabled publickey
debug1: Next authentication method: publickey
debug1: Trying private key: /cygdrive/c/program files/copssh/.ssh/identity
debug3: no such identity: /cygdrive/c/program files/copssh/.ssh/identity
debug1: Offering public key: /cygdrive/c/program files/copssh/.ssh/id_rsa
debug3: send_pubkey_test
debug2: we sent a publickey packet, wait for reply
debug3: Wrote 372 bytes for a total of 1633
debug3: Received SSH2_MSG_IGNORE
debug1: Server accepts key: pkalg ssh-rsa blen 277
debug2: input_userauth_pk_ok: fp (...)
debug3: sign_and_send_pubkey
debug1: read PEM private key done: type RSA
debug3: Wrote 644 bytes for a total of 2277
debug3: Received SSH2_MSG_IGNORE
debug1: Authentication succeeded (publickey).
debug2: fd 4 setting O_NONBLOCK
debug2: fd 5 setting O_NONBLOCK
debug1: channel 0: new [client-session]
debug3: ssh_session2_open: channel_new: 0
debug2: channel 0: send open
debug1: Entering interactive session.
debug3: Wrote 68 bytes for a total of 2345
debug3: Received SSH2_MSG_IGNORE
debug2: callback start
debug2: client_session2_setup: id 0
debug1: Sending subsystem: sftp
debug2: channel 0: request subsystem confirm 1
debug2: fd 3 setting TCP_NODELAY
debug2: callback done
debug2: channel 0: open confirm rwindow 65536 rmax 32768
debug3: Wrote 68 bytes for a total of 2413
debug3: Wrote 52 bytes for a total of 2465
debug3: Received SSH2_MSG_IGNORE
debug2: channel_input_status_confirm: type 99 id 0
debug2: subsystem request accepted on channel 0
debug3: Received SSH2_MSG_IGNORE
debug3: Wrote 68 bytes for a total of 2533
debug3: Received SSH2_MSG_IGNORE
debug3: Wrote 84 bytes for a total of 2617
debug3: Received SSH2_MSG_IGNORE
debug3: Wrote 68 bytes for a total of 2685
debug3: Received SSH2_MSG_IGNORE
debug3: Wrote 16436 bytes for a total of 19121
debug3: Wrote 4148 bytes for a total of 23269
debug3: Wrote 12372 bytes for a total of 35641
debug3: Wrote 16436 bytes for a total of 52077
debug3: Wrote 4148 bytes for a total of 56225
debug3: Wrote 12196 bytes for a total of 68421
debug3: Received SSH2_MSG_IGNORE
debug2: channel 0: rcvd adjust 32899
debug3: Wrote 212 bytes for a total of 68633
debug3: Received SSH2_MSG_IGNORE
debug3: Wrote 16436 bytes for a total of 85069
debug3: Wrote 4148 bytes for a total of 89217
debug3: Received SSH2_MSG_IGNORE
debug2: channel 0: rcvd adjust 98337
debug3: Received SSH2_MSG_IGNORE
debug3: Wrote 12372 bytes for a total of 101589
debug3: Wrote 16436 bytes for a total of 118025
debug3: Wrote 4148 bytes for a total of 122173
debug3: Wrote 12372 bytes for a total of 134545
debug3: Wrote 16436 bytes for a total of 150981
debug3: Received SSH2_MSG_IGNORE
debug3: Wrote 4148 bytes for a total of 155129
debug3: Wrote 12372 bytes for a total of 167501
debug3: Received SSH2_MSG_IGNORE
debug2: channel 0: rcvd adjust 196674
debug3: Received SSH2_MSG_IGNORE
debug3: Wrote 16436 bytes for a total of 183937
debug3: Received SSH2_MSG_IGNORE
debug3: Wrote 4148 bytes for a total of 188085
debug3: Wrote 12372 bytes for a total of 200457
debug3: Wrote 16436 bytes for a total of 216893
debug3: Wrote 4148 bytes for a total of 221041
debug3: Wrote 12372 bytes for a total of 233413
debug3: Wrote 16436 bytes for a total of 249849
debug3: Received SSH2_MSG_IGNORE
debug3: Wrote 4148 bytes for a total of 253997
debug3: Wrote 12372 bytes for a total of 266369
debug3: Received SSH2_MSG_IGNORE
debug3: Wrote 16436 bytes for a total of 282805
debug3: Wrote 4148 bytes for a total of 286953
debug3: Wrote 12372 bytes for a total of 299325
debug3: Received SSH2_MSG_IGNORE
debug2: channel 0: rcvd adjust 131204
debug3: Wrote 16436 bytes for a total of 315761
debug3: Received SSH2_MSG_IGNORE
debug3: Wrote 4148 bytes for a total of 319909
debug3: Received SSH2_MSG_IGNORE
debug3: Wrote 12372 bytes for a total of 332281
debug3: Wrote 16436 bytes for a total of 348717
debug3: Wrote 4148 bytes for a total of 352865
debug3: Wrote 12372 bytes for a total of 365237
debug3: Wrote 16436 bytes for a total of 381673
debug3: Wrote 4148 bytes for a total of 385821
debug3: Received SSH2_MSG_IGNORE
debug3: Wrote 12372 bytes for a total of 398193
debug3: Wrote 16436 bytes for a total of 414629
debug3: Received SSH2_MSG_IGNORE
debug3: Wrote 4148 bytes for a total of 418777
debug3: Wrote 12372 bytes for a total of 431149
debug3: Wrote 16436 bytes for a total of 447585
debug3: Received SSH2_MSG_IGNORE
debug2: channel 0: rcvd adjust 393348
debug3: Received SSH2_MSG_IGNORE
debug3: Wrote 4148 bytes for a total of 451733
debug3: Received SSH2_MSG_IGNORE
debug3: Wrote 12372 bytes for a total of 464105
debug3: Wrote 16436 bytes for a total of 480541
debug3: Wrote 4148 bytes for a total of 484689
debug3: Wrote 12372 bytes for a total of 497061
debug3: Wrote 16436 bytes for a total of 513497
debug3: Wrote 4148 bytes for a total of 517645
debug3: Received SSH2_MSG_IGNORE
debug3: Wrote 12372 bytes for a total of 530017
debug3: Wrote 16436 bytes for a total of 546453
debug3: Received SSH2_MSG_IGNORE
debug3: Wrote 4148 bytes for a total of 550601
debug3: Wrote 12372 bytes for a total of 562973
debug3: Wrote 16436 bytes for a total of 579409
debug3: Received SSH2_MSG_IGNORE
debug3: Wrote 4148 bytes for a total of 583557
debug3: Wrote 12372 bytes for a total of 595929
debug3: Wrote 16436 bytes for a total of 612365
debug3: Received SSH2_MSG_IGNORE
debug3: Wrote 4148 bytes for a total of 616513
debug3: Wrote 12372 bytes for a total of 628885
debug3: Wrote 16436 bytes for a total of 645321
debug3: Received SSH2_MSG_IGNORE
debug3: Wrote 4148 bytes for a total of 649469
debug3: Wrote 12372 bytes for a total of 661841
debug3: Wrote 16436 bytes for a total of 678277
debug3: Wrote 4148 bytes for a total of 682425
debug3: Received SSH2_MSG_IGNORE
debug3: Wrote 12372 bytes for a total of 694797
debug3: Wrote 16436 bytes for a total of 711233
debug3: Received SSH2_MSG_IGNORE
debug2: channel 0: rcvd adjust 738120
debug3: Received SSH2_MSG_IGNORE
debug3: Wrote 4148 bytes for a total of 715381
debug3: Received SSH2_MSG_IGNORE
更新 1
根据@Daniel Lawson 的建议，我尝试使用 netsh 将 VPN 接口的 MTU 限制为 1280，以避免在通往服务器的路径上 MTU 不匹配的情况下填充客户端的 TCP 缓冲区。转移仍然停滞在大约同一点。我还尝试断开 VPN 连接并将物理接口的 MTU 限制为 1280，但结果相同。
注意（TLDR）：正如 salva 所说，快速修复方法是更新到Net::SFTP::Foreign 1.70_08或更高版本。存在一个错误，导致该库无法queue_size在 Windows 中使用正确的默认值。请继续阅读我的原始解决方案。
我能够通过将 Perl Net::SFTP::Foreign 模块的queue_size参数从默认的 32 减少到 23 来消除停滞的传输。这是一个与网络性能相关的变量，当它减少时我没有感觉到速度差异。对于生产，为了安全起见，我将把它调回 16。
队列大小 => $大小
读取和写入请求被流水线化，以最大化传输吞吐量。此选项允许设置可以同时等待服务器响应的最大请求数。
queue_size 选项适用于 Net::SFTP::Foreign 的new、get、put、rget和rput方法。
queue_size如果您使用 Net::SFTP::Foreign，则可以在构造函数或各个方法调用的末尾附加该参数。
my $sftp = Net::SFTP::Foreign->new( $host, queue_size => 16 );
# -- OR --
$sftp->put( $local_file, $remote_file, queue_size => 16 );
我正在使用 Net::SFTP::Foreign::Compat 包装器来实现类似 Net::SFTP 的 API。该包装器允许您设置默认参数以与底层 Net::SFTP::Foreign 方法调用一起使用。
use Net::SFTP::Foreign::Compat;
# Note that the Compat CPAN documentation is INCORRECT
# The DEFAULTS hash is under Compat, not Foreign
$Net::SFTP::Foreign::Compat::DEFAULTS{ new } = [ queue_size => 16 ];
# -- OR --
$Net::SFTP::Foreign::Compat::DEFAULTS{ put } = [ queue_size => 16 ];
my $sftp = Net::SFTP::Foreign::Compat->new( $host, %options );
相关思考：最大工作queue_size23 和默认block_size32KB 与传输停止之前发送的字节数相关。23 * 32KB 略高于 700KB。我无法解释为什么我需要限制queue_size此部署，但它解决了我的问题。
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