ssh连上几秒就断开了
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参考技术A 可能设置了TIMEOUT，可以尝试在ssh连接上去后立马写TIMEOUT=0或TMOUT=0Swift iOS -AshleyMills Reachability 每隔几秒就会打开和关闭 wifi
【中文标题】Swift iOS -AshleyMills Reachability 每隔几秒就会打开和关闭 wifi【英文标题】：Swift iOS -AshleyMills Reachability keeps toggling wifi on and off every few secs 【发布时间】：2018-05-03 17:49:50 【问题描述】：我从AshleyMills Reachability下载了iOS示例Reachability项目
它有一个 networkStatus 标签，上面写着：Wifi 或 No Connection
在它下面有一个 hostNameLabel，上面写着：No host name 或 google.com 或 invalidhost
当我在我的设备上运行该应用程序时，它每 5 秒以下列方式重复循环连接：
第一个 5 秒：
第二个 5 秒：
第三个 5 秒：
从第 1 次、第 2 次和第 3 次重新开始循环并不断重复。
我使用的是家庭 wifi，并且我的互联网连接很好（任何其他应用程序都没有问题）。 为什么它会像这样不断循环，而不是停留在Wifi + google.com（第二个循环）
ViewController 文件：
class ViewController: UIViewController
let networkStatus: UILabel =
let label = UILabel()
label.translatesAutoresizingMaskIntoConstraints = false
label.font = UIFont.systemFont(ofSize: 21)
label.textColor = .black
label.numberOfLines = 0
label.sizeToFit()
label.text = "Status"
label.textAlignment = .center
return label
()
let hostNameLabel: UILabel =
let label = UILabel()
label.translatesAutoresizingMaskIntoConstraints = false
label.font = UIFont.systemFont(ofSize: 21)
label.textColor = .black
label.numberOfLines = 0
label.sizeToFit()
label.text = "Host"
label.textAlignment = .center
return label
()
var reachability: Reachability?
let hostNames = [nil, "google.com", "invalidhost"]
var hostIndex = 0
override func viewDidLoad()
super.viewDidLoad()
setConstraints()
startHost(at: 0)
func startHost(at index: Int)
stopNotifier()
setupReachability(hostNames[index], useClosures: true)
startNotifier()
DispatchQueue.main.asyncAfter(deadline: .now() + 5)
self.startHost(at: (index + 1) % 3)
func setupReachability(_ hostName: String?, useClosures: Bool)
let reachability: Reachability?
if let hostName = hostName
reachability = Reachability(hostname: hostName)
hostNameLabel.text = hostName
else
reachability = Reachability()
hostNameLabel.text = "No host name"
self.reachability = reachability
print("--- set up with host name: \(hostNameLabel.text!)")
if useClosures
reachability?.whenReachable = reachability in
self.updateLabelColourWhenReachable(reachability)
reachability?.whenUnreachable = reachability in
self.updateLabelColourWhenNotReachable(reachability)
else
NotificationCenter.default.addObserver(
self,
selector: #selector(reachabilityChanged(_:)),
name: .reachabilityChanged,
object: reachability
)
func startNotifier()
print("--- start notifier")
do
try reachability?.startNotifier()
catch
networkStatus.textColor = .red
networkStatus.text = "Unable to start\nnotifier"
return
func stopNotifier()
print("--- stop notifier")
reachability?.stopNotifier()
NotificationCenter.default.removeObserver(self, name: .reachabilityChanged, object: nil)
reachability = nil
func updateLabelColourWhenReachable(_ reachability: Reachability)
print("\(reachability.description) - \(reachability.connection)")
if reachability.connection == .wifi
self.networkStatus.textColor = .green
else
self.networkStatus.textColor = .blue
self.networkStatus.text = "\(reachability.connection)"
func updateLabelColourWhenNotReachable(_ reachability: Reachability)
print("\(reachability.description) - \(reachability.connection)")
self.networkStatus.textColor = .red
self.networkStatus.text = "\(reachability.connection)"
@objc func reachabilityChanged(_ note: Notification)
let reachability = note.object as! Reachability
if reachability.connection != .none
updateLabelColourWhenReachable(reachability)
else
updateLabelColourWhenNotReachable(reachability)
func setConstraints()
view.addSubview(networkStatus)
view.addSubview(hostNameLabel)
networkStatus.leftAnchor.constraint(equalTo: view.leftAnchor, constant: 8).isActive = true
networkStatus.rightAnchor.constraint(equalTo: view.rightAnchor, constant: -8).isActive = true
networkStatus.centerYAnchor.constraint(equalTo: view.centerYAnchor).isActive = true
hostNameLabel.leftAnchor.constraint(equalTo: view.leftAnchor, constant: 8).isActive = true
hostNameLabel.rightAnchor.constraint(equalTo: view.rightAnchor, constant: -8).isActive = true
hostNameLabel.topAnchor.constraint(equalTo: networkStatus.bottomAnchor, constant: 20).isActive = true
deinit
stopNotifier()
可达性文件：
import SystemConfiguration
import Foundation
public enum ReachabilityError: Error
case FailedToCreateWithAddress(sockaddr_in)
case FailedToCreateWithHostname(String)
case UnableToSetCallback
case UnableToSetDispatchQueue
@available(*, unavailable, renamed: "Notification.Name.reachabilityChanged")
public let ReachabilityChangedNotification = NSNotification.Name("ReachabilityChangedNotification")
extension Notification.Name
public static let reachabilityChanged = Notification.Name("reachabilityChanged")
func callback(reachability: SCNetworkReachability, flags: SCNetworkReachabilityFlags, info: UnsafeMutableRawPointer?)
guard let info = info else return
let reachability = Unmanaged<Reachability>.fromOpaque(info).takeUnretainedValue()
reachability.reachabilityChanged()
public class Reachability
public typealias NetworkReachable = (Reachability) -> ()
public typealias NetworkUnreachable = (Reachability) -> ()
@available(*, unavailable, renamed: "Connection")
public enum NetworkStatus: CustomStringConvertible
case notReachable, reachableViaWiFi, reachableViaWWAN
public var description: String
switch self
case .reachableViaWWAN: return "Cellular"
case .reachableViaWiFi: return "WiFi"
case .notReachable: return "No Connection"
public enum Connection: CustomStringConvertible
case none, wifi, cellular
public var description: String
switch self
case .cellular: return "Cellular"
case .wifi: return "WiFi"
case .none: return "No Connection"
public var whenReachable: NetworkReachable?
public var whenUnreachable: NetworkUnreachable?
@available(*, deprecated: 4.0, renamed: "allowsCellularConnection")
public let reachableOnWWAN: Bool = true
/// Set to `false` to force Reachability.connection to .none when on cellular connection (default value `true`)
public var allowsCellularConnection: Bool
// The notification center on which "reachability changed" events are being posted
public var notificationCenter: NotificationCenter = NotificationCenter.default
@available(*, deprecated: 4.0, renamed: "connection.description")
public var currentReachabilityString: String
return "\(connection)"
@available(*, unavailable, renamed: "connection")
public var currentReachabilityStatus: Connection
return connection
public var connection: Connection
guard isReachableFlagSet else return .none
// If we're reachable, but not on an iOS device (i.e. simulator), we must be on WiFi
guard isRunningOnDevice else return .wifi
var connection = Connection.none
if !isConnectionRequiredFlagSet
connection = .wifi
if isConnectionOnTrafficOrDemandFlagSet
if !isInterventionRequiredFlagSet
connection = .wifi
if isOnWWANFlagSet
if !allowsCellularConnection
connection = .none
else
connection = .cellular
return connection
fileprivate var previousFlags: SCNetworkReachabilityFlags?
fileprivate var isRunningOnDevice: Bool =
#if targetEnvironment(simulator)
return false
#else
return true
#endif
()
fileprivate var notifierRunning = false
fileprivate let reachabilityRef: SCNetworkReachability
fileprivate let reachabilitySerialQueue = DispatchQueue(label: "uk.co.ashleymills.reachability")
fileprivate var usingHostname = false
required public init(reachabilityRef: SCNetworkReachability, usingHostname: Bool = false)
allowsCellularConnection = true
self.reachabilityRef = reachabilityRef
self.usingHostname = usingHostname
public convenience init?(hostname: String)
guard let ref = SCNetworkReachabilityCreateWithName(nil, hostname) else return nil
self.init(reachabilityRef: ref, usingHostname: true)
public convenience init?()
var zeroAddress = sockaddr()
zeroAddress.sa_len = UInt8(MemoryLayout<sockaddr>.size)
zeroAddress.sa_family = sa_family_t(AF_INET)
guard let ref = SCNetworkReachabilityCreateWithAddress(nil, &zeroAddress) else return nil
self.init(reachabilityRef: ref)
deinit
stopNotifier()
public extension Reachability
// MARK: - *** Notifier methods ***
func startNotifier() throws
guard !notifierRunning else return
var context = SCNetworkReachabilityContext(version: 0, info: nil, retain: nil, release: nil, copyDescription: nil)
context.info = UnsafeMutableRawPointer(Unmanaged<Reachability>.passUnretained(self).toOpaque())
if !SCNetworkReachabilitySetCallback(reachabilityRef, callback, &context)
stopNotifier()
throw ReachabilityError.UnableToSetCallback
if !SCNetworkReachabilitySetDispatchQueue(reachabilityRef, reachabilitySerialQueue)
stopNotifier()
throw ReachabilityError.UnableToSetDispatchQueue
// Perform an initial check
reachabilitySerialQueue.async
self.reachabilityChanged()
notifierRunning = true
func stopNotifier()
defer notifierRunning = false
SCNetworkReachabilitySetCallback(reachabilityRef, nil, nil)
SCNetworkReachabilitySetDispatchQueue(reachabilityRef, nil)
// MARK: - *** Connection test methods ***
@available(*, deprecated: 4.0, message: "Please use `connection != .none`")
var isReachable: Bool
guard isReachableFlagSet else return false
if isConnectionRequiredAndTransientFlagSet
return false
if isRunningOnDevice
if isOnWWANFlagSet && !reachableOnWWAN
// We don't want to connect when on cellular connection
return false
return true
@available(*, deprecated: 4.0, message: "Please use `connection == .cellular`")
var isReachableViaWWAN: Bool
// Check we're not on the simulator, we're REACHABLE and check we're on WWAN
return isRunningOnDevice && isReachableFlagSet && isOnWWANFlagSet
@available(*, deprecated: 4.0, message: "Please use `connection == .wifi`")
var isReachableViaWiFi: Bool
// Check we're reachable
guard isReachableFlagSet else return false
// If reachable we're reachable, but not on an iOS device (i.e. simulator), we must be on WiFi
guard isRunningOnDevice else return true
// Check we're NOT on WWAN
return !isOnWWANFlagSet
var description: String
let W = isRunningOnDevice ? (isOnWWANFlagSet ? "W" : "-") : "X"
let R = isReachableFlagSet ? "R" : "-"
let c = isConnectionRequiredFlagSet ? "c" : "-"
let t = isTransientConnectionFlagSet ? "t" : "-"
let i = isInterventionRequiredFlagSet ? "i" : "-"
let C = isConnectionOnTrafficFlagSet ? "C" : "-"
let D = isConnectionOnDemandFlagSet ? "D" : "-"
let l = isLocalAddressFlagSet ? "l" : "-"
let d = isDirectFlagSet ? "d" : "-"
return "\(W)\(R) \(c)\(t)\(i)\(C)\(D)\(l)\(d)"
fileprivate extension Reachability
func reachabilityChanged()
guard previousFlags != flags else return
let block = connection != .none ? whenReachable : whenUnreachable
DispatchQueue.main.async
if self.usingHostname
print("USING HOSTNAME ABOUT TO CALL BLOCK")
block?(self)
self.notificationCenter.post(name: .reachabilityChanged, object:self)
previousFlags = flags
var isOnWWANFlagSet: Bool
#if os(iOS)
return flags.contains(.isWWAN)
#else
return false
#endif
var isReachableFlagSet: Bool
return flags.contains(.reachable)
var isConnectionRequiredFlagSet: Bool
return flags.contains(.connectionRequired)
var isInterventionRequiredFlagSet: Bool
return flags.contains(.interventionRequired)
var isConnectionOnTrafficFlagSet: Bool
return flags.contains(.connectionOnTraffic)
var isConnectionOnDemandFlagSet: Bool
return flags.contains(.connectionOnDemand)
var isConnectionOnTrafficOrDemandFlagSet: Bool
return !flags.intersection([.connectionOnTraffic, .connectionOnDemand]).isEmpty
var isTransientConnectionFlagSet: Bool
return flags.contains(.transientConnection)
var isLocalAddressFlagSet: Bool
return flags.contains(.isLocalAddress)
var isDirectFlagSet: Bool
return flags.contains(.isDirect)
var isConnectionRequiredAndTransientFlagSet: Bool
return flags.intersection([.connectionRequired, .transientConnection]) == [.connectionRequired, .transientConnection]
var flags: SCNetworkReachabilityFlags
var flags = SCNetworkReachabilityFlags()
if SCNetworkReachabilityGetFlags(reachabilityRef, &flags)
print("Returning flags \(flags)")
return flags
else
return SCNetworkReachabilityFlags()
【问题讨论】：
这只是一个测试应用程序，演示了各种类型的连接会发生什么。首先没有主机，然后是 google.com ，然后是无效的主机名 我想通了。我实际上是在使用您的代码的另一个项目中使用它。它工作得很好。谢谢！ 【参考方案1】：我查看了代码并找到了答案。在ViewController 文件中，startHost() 函数中有一个定时器，每 5 秒循环一次。
func startHost(at index: Int)
stopNotifier()
setupReachability(hostNames[index], useClosures: true)
startNotifier()
// Timer is HERE
DispatchQueue.main.asyncAfter(deadline: .now() + 5)
self.startHost(at: (index + 1) % 3)
【讨论】：
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