VS Code Remote-SSH通过跳板机连接目标服务器超时

问题现象 #

• 网络访问限制：仅可通过跳板机连接目标服务器，本地到跳板机的SSH连接正常
• 报错表现：从跳板机尝试连接目标服务器时，VS Code弹出错误提示：Could not establish connection to "TargetMachine": The connection timed out.
• 卡顿阶段：报错触发前，VS Code长期停留在 Setting up SSH Host TargetMachine: (details) Initializing VS Code Server 状态
• 运行环境：本地设备为MacOS（darwin arm64），Remote-SSH插件版本为0.82.1

运行日志 #

[18:49:26.861] Log Level: 2
[18:49:26.862] remote-ssh@0.82.1
[18:49:26.862] darwin arm64
[18:49:26.864] SSH Resolver called for "ssh-remote+7b22686f7xxxxxxxxxx", attempt 1
[18:49:26.864] "remote.SSH.useLocalServer": false
[18:49:26.864] "remote.SSH.showLoginTerminal": false
[18:49:26.865] "remote.SSH.remotePlatform": {}
[18:49:26.865] "remote.SSH.path": undefined
[18:49:26.865] "remote.SSH.configFile": undefined
[18:49:26.865] "remote.SSH.useFlock": true
[18:49:26.865] "remote.SSH.lockfilesInTmp": false
[18:49:26.865] "remote.SSH.localServerDownload": auto
[18:49:26.865] "remote.SSH.remoteServerListenOnSocket": false
[18:49:26.866] "remote.SSH.showLoginTerminal": false
[18:49:26.866] "remote.SSH.defaultExtensions": []
[18:49:26.867] "remote.SSH.loglevel": 2
[18:49:26.867] "remote.SSH.enableDynamicForwarding": true
[18:49:26.867] "remote.SSH.enableRemoteCommand": false
[18:49:26.867] "remote.SSH.serverPickPortsFromRange": {}
[18:49:26.867] "remote.SSH.serverInstallPath": {}
[18:49:26.874] SSH Resolver called for host: TargetMachine
[18:49:26.874] Setting up SSH remote "TargetMachine"
[18:49:26.876] Using commit id "30d9c6cdxxxxxxxxxx" and quality "stable" for server
[18:49:26.878] Install and start server if needed
[18:49:27.602] PATH: /Users/songjia/.gem/ruby/3.1.1/bin:/Users/songjia/.gem/ruby/X.X.0/bin:/usr/local/opt/ruby/bin:/Users/songjia/.gem/ruby/3.1.1/bin:/Users/songjia/.rubies/ruby-3.1.1/lib/ruby/gems/3.1.0/bin:/Users/songjia/.rubies/ruby-3.1.1/bin:/opt/homebrew/Caskroom/miniforge/base/bin:/opt/homebrew/Caskroom/miniforge/base/condabin:/opt/homebrew/bin:/opt/homebrew/sbin:/usr/local/bin:/usr/bin:/bin:/usr/sbin:/sbin:/Users/songjia/.rvm/bin
[18:49:27.602] Checking ssh with "ssh -V"
[18:49:27.611] > OpenSSH_8.1p1, LibreSSL 2.7.3

[18:49:27.612] Running script with connection command: ssh -T -D 56756 -o ConnectTimeout=40 'TargetMachine' bash
[18:50:07.950] > Connection timed out during banner exchange
[18:50:07.950] Got some output, clearing connection timeout
[18:50:08.069] "install" terminal command done
[18:50:08.070] Install terminal quit with output: Connection timed out during banner exchange
[18:50:08.070] Received install output: Connection timed out during banner exchange
[18:50:08.073] Resolver error: Error: The connection timed out
    at Function.Offline (/Users/songjia/.vscode/extensions/ms-vscode-remote.remote-ssh-0.82.1/out/extension.js:1:585270)
    at /Users/songjia/.vscode/extensions/ms-vscode-remote.remote-ssh-0.82.1/out/extension.js:1:582845)
    at Object.t.handleInstallOutput (/Users/songjia/.vscode/extensions/ms-vscode-remote.remote-ssh-0.82.1/out/extension.js:1:583059)
    at Object.t.tryInstall (/Users/songjia/.vscode/extensions/ms-vscode-remote.remote-ssh-0.82.1/out/extension.js:1:680958)
    at processTicksAndRejections (node:internal/process/task_queues:96:5)
    at async /Users/songjia/.vscode/extensions/ms-vscode-remote.remote-ssh-0.82.1/out/extension.js:1:643905)
    at async Object.t.withShowDetailsEvent (/Users/songjia/.vscode/extensions/ms-vscode-remote.remote-ssh-0.82.1/out/extension.js:1:647221)
    at async Object.t.resolve (/Users/songjia/.vscode/extensions/ms-vscode-remote.remote-ssh-0.82.1/out/extension.js:1:644955)
    at async /Users/songjia/.vscode/extensions/ms-vscode-remote.remote-ssh-0.82.1/out/extension.js:1:727005)
[18:50:08.085] ------

根因定位 #

日志核心报错为Connection timed out during banner exchange，说明SSH链路在跳板机转发到目标服务器的握手阶段就已经超时，连接根本没走到VS Code Server初始化环节，和VS Code Server安装包损坏、目标机权限不足类问题无关。

排查&解决步骤 #

按优先级从高到低操作：

1. 先排除原生SSH链路故障
   完全退出VS Code，打开本地Mac终端直接执行ssh TargetMachine，看是否能正常登录目标服务器：
   • 如果原生SSH也连不上，问题和VS Code无关：先检查~/.ssh/config中TargetMachine的ProxyJump配置项是否正确，确认跳板机地址、用户名、端口、私钥路径无拼写错误；再手动登录跳板机，在跳板机终端内直接执行ssh <目标服务器IP>，确认跳板机到目标机的网络连通性、SSH端口开放状态、防火墙规则、私钥权限正常，排除目标机sshd服务宕机、路由不通的问题。
   • 如果原生SSH可以正常登录，再进行后续VS Code相关配置调整。
2. 调整VS Code Remote-SSH配置
   • 调大连接超时阈值：打开VS Code设置，搜索remote.SSH.connectTimeout，将默认的40秒修改为120秒，跨跳板机的多跳SSH链路网络延迟高时，40秒不足以完成SSH握手流程。
   • 临时关闭动态转发：搜索remote.SSH.enableDynamicForwarding，将值改为false，部分企业跳板机的安全策略会拦截动态端口转发请求，导致SSH握手卡住。
   • 对齐SSH参数：检查~/.ssh/config中TargetMachine的配置项，不要额外添加强制IPv6、自定义加密算法之类的特殊参数，和原生终端能正常连通时使用的SSH参数保持一致。
3. 清理残留锁文件
   如果之前曾成功通过VS Code连接过目标服务器，先通过原生SSH登录目标机，执行rm -rf ~/.vscode-server/bin/*/lockfile删除残留的VS Code Server锁文件，避免旧进程占用导致初始化卡住。
4. 高阶排查
   以上操作都无效时，将remote.SSH.loglevel设置为3开启调试日志，重连时查看SSH握手的详细输出，定位具体是跳板机转发被拦截，还是目标机sshd响应超时。

内容的提问来源于stack exchange，提问作者sjchasel