VEF Access 502 Gateway Error

[Rodster363]

Just a heads up, I've been trying to access VEF to login and receive repeated 502 Gateway Error messages, similar to PlanetS yesterday. Same with PS right now too.

I googled for a VEF twitter account and found one. Old tweets, nothing current but one tweet had a link which got me into VEF.

I've signed in, here I am and am posting this just FYI.

[Jenny48549]

Both VEF and PSuzy are once again undergoing DDoS attacks. Sysadmin is attempting to mitigate them but access will be spotty until they subside.

Sorry folks, hang in there, it's going to be a bumpy ride till then.

[bowlinggreen]

Same here, couldn't get on earlier, but got on just now.

Hopefully this stops soon.

[ballyhoo]

thank god for small miracles, she's working now.
Ginger Rogers, please forgive me!

[Baranovich]

Same here, I was getting the 502 error for about five hours yesterday. At first I wasn't able to access any part of VEF, then I was intermittently able to open a particular page or link but then it would shut down again. Finally cleared up this morning!

[Leprechaun]

[pharoahegypt]

I had the same error trying to access both VEF & NCF last night, but not PltSzy for some reason, which seemed fine, for once. lol.

[footstep]

Ddos attack. Denial of service. Hackers.
Ten, hundred_Thousand ip connecting to servers at the same time , server Boum!
They find that funny.
They should work building true applications.

[footstep]

For .net developers(cheers guys):

#region Using

using System;
using System.Web;
using System.Collections.Generic;
using System.Collections.Specialized;
using System.Timers;

#endregion

/// <summary>
/// Block the response to attacking IP addresses.
/// </summary>
public class DosAttackModule : IHttpModule
{

#region IHttpModule Members

void IHttpModule.Dispose()
{
// Nothing to dispose;
}

void IHttpModule.Init(HttpApplication context)
{
context.BeginRequest += new EventHandler(context_BeginRequest);
}

#endregion

#region Private fields

private static Dictionary<string, short> _IpAdresses = new Dictionary<string, short>();
private static Stack<string> _Banned = new Stack<string>();
private static Timer _Timer = CreateTimer();
private static Timer _BannedTimer = CreateBanningTimer();

#endregion

private const int BANNED_REQUESTS = 10;
private const int REDUCTION_INTERVAL = 1000; // 1 second
private const int RELEASE_INTERVAL = 5 * 60 * 1000; // 5 minutes

private void context_BeginRequest(object sender, EventArgs e)
{
string ip = HttpContext.Current.Request.UserHostAddress;
if (_Banned.Contains(ip))
{
HttpContext.Current.Response.StatusCode = 403;
HttpContext.Current.Response.End();
}

CheckIpAddress(ip);
}

/// <summary>
/// Checks the requesting IP address in the collection
/// and bannes the IP if required.
/// </summary>
private static void CheckIpAddress(string ip)
{
if (!_IpAdresses.ContainsKey(ip))
{
_IpAdresses[ip] = 1;
}
else if (_IpAdresses[ip] == BANNED_REQUESTS)
{
_Banned.Push(ip);
_IpAdresses.Remove(ip);
}
else
{
_IpAdresses[ip]++;
}
}

#region Timers

/// <summary>
/// Creates the timer that substract a request
/// from the _IpAddress dictionary.
/// </summary>
private static Timer CreateTimer()
{
Timer timer = GetTimer(REDUCTION_INTERVAL);
timer.Elapsed += new ElapsedEventHandler(TimerElapsed);
return timer;
}

/// <summary>
/// Creates the timer that removes 1 banned IP address
/// everytime the timer is elapsed.
/// </summary>
/// <returns></returns>
private static Timer CreateBanningTimer()
{
Timer timer = GetTimer(RELEASE_INTERVAL);
timer.Elapsed += delegate { _Banned.Pop(); };
return timer;
}

/// <summary>
/// Creates a simple timer instance and starts it.
/// </summary>
/// <param name="interval">The interval in milliseconds.</param>
private static Timer GetTimer(int interval)
{
Timer timer = new Timer();
timer.Interval = interval;
timer.Start();

return timer;
}

/// <summary>
/// Substracts a request from each IP address in the collection.
/// </summary>
private static void TimerElapsed(object sender, ElapsedEventArgs e)
{
foreach (string key in _IpAdresses.Keys)
{
_IpAdresses[key]--;
if (_IpAdresses[key] == 0)
_IpAdresses.Remove(key);
}
}

#endregion

}
and web.config:

<system.web> section:< httpModules >
< add type = " DosAttackModule " name = " DosAttackModule " />
</ httpModules >



Available until asp.net mvc 5.(didnd' adapt and test it on core).