{"record":{"id":"8f2246765830e090","repo":"fatedier/frp","slug":"open-ssh-channel-error-v","errorCode":null,"errorMessage":"open ssh channel error: %v","messagePattern":"open ssh channel error: (.+?)","errorType":"exception","errorClass":null,"httpStatus":null,"severity":"error","filePath":"pkg/ssh/server.go","lineNumber":370,"sourceCode":"\t\t\t\treturn\n\t\t\t}\n\t\tcase <-s.doneCh:\n\t\t\treturn\n\t\t}\n\t}\n}\n\nfunc (s *TunnelServer) openConn(addr *tcpipForward) (net.Conn, error) {\n\tpayload := forwardedTCPPayload{\n\t\tAddr: addr.Host,\n\t\tPort: addr.Port,\n\t\t// Note: Here is just for compatibility, not the real source address.\n\t\tOriginAddr: addr.Host,\n\t\tOriginPort: addr.Port,\n\t}\n\tchannel, reqs, err := s.sshConn.OpenChannel(ChannelTypeServerOpenChannel, ssh.Marshal(&payload))\n\tif err != nil {\n\t\treturn nil, fmt.Errorf(\"open ssh channel error: %v\", err)\n\t}\n\tgo ssh.DiscardRequests(reqs)\n\n\tconn := netpkg.WrapReadWriteCloserToConn(channel, s.underlyingConn)\n\treturn conn, nil\n}\n\nfunc (s *TunnelServer) waitProxyStatusReady(name string, timeout time.Duration) (*proxy.WorkingStatus, error) {\n\tticker := time.NewTicker(100 * time.Millisecond)\n\tdefer ticker.Stop()\n\n\ttimer := time.NewTimer(timeout)\n\tdefer timer.Stop()\n\n\tstatusExporter := s.vc.Service().StatusExporter()\n\n\tfor {\n\t\tselect {","sourceCodeStart":352,"sourceCodeEnd":388,"githubUrl":"https://github.com/fatedier/frp/blob/6c8a8d0a97d03b44e9528d30b30c70cb9d61b405/pkg/ssh/server.go#L352-L388","documentation":"Emitted by TunnelServer.openConn when the server cannot open a ChannelTypeServerOpenChannel back over the SSH connection to the visitor's client. For remote-visited traffic, data flows through a second SSH channel opened by frps toward the client; if the client rejects or the connection is dead, this error surfaces on the visitor's connection path.","triggerScenarios":"Client disconnected or is shutting down right as a visitor connects; client's SSH implementation rejects the channel open; too many open channels exhausting SSH channel windows; underlying TCP connection reset between gateway and tunnel client.","commonSituations":"Visitor traffic racing client shutdown/restart; NAT idle timeouts killing the SSH connection while the gateway still routes to it; resource-exhausted clients dropping new channels.","solutions":["Confirm the frp SSH tunnel client is still connected and healthy (frps dashboard / logs).","Have the visitor retry the connection — transient races during client reconnect resolve themselves.","Keep the gateway-client connection alive with SSH keepalives/heartbeat settings so NATs do not kill it silently.","If it persists, check client-side logs for channel-open rejections and raise channel limits if a custom SSH stack is in play."],"exampleFix":null,"handlingStrategy":"retry","validationCode":null,"typeGuard":null,"tryCatchPattern":"// visitor-side retry with backoff when a channel open fails\nvar conn net.Conn\nerr := retry.Do(\n    func() error {\n        var e error\n        conn, e = dialVisitor()\n        return e\n    },\n    retry.OnError(func(err error) bool {\n        return strings.Contains(err.Error(), \"open ssh channel error\")\n    }),\n    retry.Attempts(3), retry.Delay(500*time.Millisecond),\n)","preventionTips":["Keep gateway<->client connections alive (SSH keepalives) so NATs do not silently kill them.","Expect transient channel-open failures during client reconnect windows; retry visitors.","Monitor client liveness on frps so dead tunnels are reaped quickly."],"tags":["ssh","network","channel","connection-lifecycle"],"backgroundTag":null,"analyzedSha":"6c8a8d0a97d03b44e9528d30b30c70cb9d61b405","analyzedAt":"2026-08-15T06:53:27.215Z","schemaVersion":2},"datasetVersion":"2026-08-15T22:17:37.221Z"}