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How to resolve network connection problems

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Posted by Nick Gammon   Australia  (23,017 posts)  [Biography] bio   Forum Administrator
Date Mon 17 Dec 2007 10:48 PM (UTC)

Amended on Thu 27 Oct 2011 07:35 PM (UTC) by Nick Gammon


Troubleshooting problems connecting to your favourite MUD / MMORPG

Are you having trouble connecting to your MUD? Before you post a message on the forum about a "client bug" - read the posting below. It will help you understand the various steps involved in connecting to a multiplayer game, and how to interpret various sorts of error messages.

First, a network diagram, to illustrate the path that a network connection is likely to take:

Network diagram

Let's take each step at a time ...

Resolve the Domain Name

One of the first things your client has to do is "resolve the domain name". What this means is that an alphabetic name (like smaug.org) has to be converted to a network address (like Packets that travel over the network are addressed by number (eg. not by name. The use of domain names is a convenience for humans.

IP address dialog

To convert a name, the client has to contact a Domain Name Server (DNS), sending it the name it wants resolved. If possible the server replies with the name converted into a number.

You can see from the network diagram above that the Domain Name Server (DNS) is number 6 on the list of steps, so there are quite a few things that can go wrong before the domain name is resolved.

Firewall (item 2 on network diagram)

Many PCs these days have a firewall installed by default, or you may have chosen to install one yourself, or upgrade the existing one. Attempting to use your client, for the first time, to access the Internet (including the DNS) may result in a warning dialog box like this (the IP address will be different):

Firewall access dialog

It is important to click "Allow" and preferably "Save the answer as a permanent rule", otherwise you will not get much further using your client to access the Internet. If you don't see a dialog box then it is possible you (or someone else) denied access previously, and it has been saved as a rule in the firewall already. If this happens you will probably see a message like this in MUSHclient:

Unable to connect to "Realms of Despair", code = 10051 (Network is unreachable)

The message "Network is unreachable" suggests that the firewall has denied access to the network to this program. In this case you would need to go into your firewall configuration, find the relevant rule, and modify it:

Firewall showing MUSHclient blocked

I notice that MUSHclient has been blocked by someone, so I click on Edit to modify the rule:

Firewall editing MUSHclient rule

Change the rule to Allow, and click OK to save and OK again to save the changes to the firewall rules. Your firewall may be different but the same general principles will apply.

Router / modem (item 3 on network diagram)

The next link on our chain is the home router / modem (or cable modem) which connects our PC to the Internet. Personally I have two boxes, one is the modem supplied by the cable company, and the other is a home router, which lets me share the Internet connection between multiple PCs. Sometimes I find that these devices fail, and powering them off and back on can help restore a lost connection. If I turn off my router, and try to connect I get this error message:

Unable to connect to "Realms of Despair", code = 10060 (Connection timed out)

Notice the different message compared to the firewall problem. This time it timed out (that is, got no response) while trying to connect.

A further possible problem is that routers often have their own firewalls. You may need to configure the firewall to allow outwards access from your PC to the MUD. However it is unlikely your router will not allow you to access your DNS server, otherwise you would not get much network browsing done at all.

If you have a dial-up connection, you may quite likely not have a router, but only a modem, in which case we move onto the next step ...

The next item to check is your modem, whether it be a cable modem, ADSL modem, dial-up modem, or some other device. If it is a dial-up modem, check it is connected. Reconnecting, or powering the modem off and on again can be helpful. The symptoms of a problem with the modem are:

  • Cannot connect to any sites on the Internet at all (eg. in your web browser)
  • Cannot send or collect mail
  • Still able to connect to other PCs on the home network (if any)

Internet Service Provider (ISP) - (item 4 on network diagram)

The next step in the network diagram is your ISP. This is your gateway to the "main" internet from your home / office / school. Potential problems with the ISP are:

  • Account not paid (so they suspended your access)
  • Allocated time up for today (eg. you used up your 2 hours' allowance).

Internet Service Provider Firewall - (item 5 on network diagram)

ISPs can also have their own firewalls. In the case of businesses or schools these may well be configured to stop employees / students playing network games. Symptoms of this are:

  • You can browse the Internet with your web browser
  • You can send and receive mail
  • You cannot connect to your favourite MUD / MMORPG.

In this case there probably isn't much you can do - attempting to ask your boss to let you play a MUD while you are supposed to be working may not be a smart career move.

Domain Name Server (DNS) - (item 6 on network diagram)

Finally we should be ready to resolve the domain name - that is, convert "smaug.org" to "" or whatever number it is. It is possible for DNS servers to go down, they are a PC like anything else, however generally speaking people who provide DNS servers provide backups (so you should see a list of DNS server addresses in your network configuration). However if you have misspelt the domain name you are likely to see an error message like this:

Unable to resolve host name for "smaugg.org", code = 11001 (Host not found)

Notice the misspelling of smaug.org, resulting in a message that it cannot "resolve host name". If you get this message you may want to check your spelling, and check that the domain name still exists. For a really old game it is possible the name has been allowed to expire.

If we successfully resolve the domain name, you should be able to see the resolved IP address in MUSHclient, like this:

IP address in world info

Notice the number in that dialog box. That shows we have successfully resolved the domain name. Now to actually connect to the world ...

Connect to the game

Now that we have a domain name resolved we can move onto actually connecting to our game. In the case of MUSHclient it caches the IP address, so that if you disconnect from the game, and then reconnect (without closing MUSHclient) it bypasses the step of getting the domain name resolved and uses the cached IP address.

Many of the steps described above also apply to actually connecting to the game, except we will be contacting a different "port" number (the game port) and a different IP address (the game IP address rather than the domain name server IP address). These differences may make the various firewalls described earlier react differently.

MUD game router - (item 8 on network diagram)

The next hurdle for our connection attempt is to get past the router at the game server end. If you are just setting up a new game you may need to read up on Port Forwarding. One site to look at is http://www.portforward.com/ - this has information about configuring routers to port-forward. Normally players of games don't need to concern themselves with this, however if you are trying to get a server to work, you should pay attention to the detail there.

MUD game firewall - (item 9 on network diagram)

A further hurdle, if you are setting up your own game, is to configure your PC (or Linux) firewall to allow incoming connections to your game. The default may well be to refuse them.

Game server - (item 10 on network diagram)

Finally we have reached the game server - but is it up? Servers (and PCs) crash. If everything else looks OK but you get a message like this:

Unable to connect to "Realms of Despair", code = 10061 (Connection refused)

This could simply mean the MUD has gone down and is being rebooted. One thing to try is MUD Connector which, amongst other things, allows you to check if the MUD is up. If it is down, there isn't much you can do except patiently wait for the admins to fix the problem.

- Nick Gammon

www.gammon.com.au, www.mushclient.com
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Posted by Nick Gammon   Australia  (23,017 posts)  [Biography] bio   Forum Administrator
Date Reply #1 on Tue 18 Dec 2007 02:24 AM (UTC)
Banned players

Another possibility is that you have been banned from the MUD for being a pest or for some other reason. Depending on how the ban was implemented you might see something like this when you connect:

--- Connected on Tuesday, December 18, 2007, 2:17 PM ---
--- Disconnected on Tuesday, December 18, 2007, 2:17 PM ---
--- Connected for 0 days, 0 hours, 0 minutes, 0 seconds. ---

Note in this case that we connected OK, but the MUD immediately dropped the connection as soon as it saw that the connection was from a banned site.

It is also possible that the MUD admins might configure their router or firewall to not allow certain IP addresses through, in which case you might get the "Connection refused" or "Connection timed out" messages.

You may genuinely not know why you have been banned, as sometimes MUDs ban a whole range of IP addresses. For example, they might choose to disallow any connection from certain ISPs, because they get a high proportion of trouble-makers from them.

They may also need to ban a range of addresses, because with dial-up connections in particular, you are usually allocated an IP address from a "pool" of available addresses. If a certain player is being a nuisance, they may keep connecting from a slightly different address each time, so the MUD needs to ban the entire range they might connect from.

"Range" bans can tend to catch innocent players as well as guilty ones. An email to the administrators of the MUD might clear things up.

- Nick Gammon

www.gammon.com.au, www.mushclient.com
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Posted by Nick Gammon   Australia  (23,017 posts)  [Biography] bio   Forum Administrator
Date Reply #2 on Tue 18 Dec 2007 07:32 PM (UTC)

Amended on Thu 27 Oct 2011 07:32 PM (UTC) by Nick Gammon

Checklist for resolving connection problems

If you have trouble connecting to your favourite online game try following these steps:

  1. Can you browse web sites?

    The first thing I do is switch to my web browser and try to contact some web site that has dynamic content (such as this forum). It is important to choose a forum, blog, or similar site which has to be refreshed every time you view it, or your web browser may simply display a cached version of a page fetched previously. Seeing a cached page doesn't prove much about your Internet connection.

    If you can see my forum, this shows:

    • The PC network interface is working and plugged in
    • The router is working
    • The (cable) modem is working
    • The ISP is working and not having technical difficulties
    • You can reach your domain name server (DNS) because it had to resolve the web site name into an IP address

    If browsing the web using a web browser works, go to Step 2, below.

    If you cannot browse the web, then you have serious problems. In fact you won't be able to read this page unless you have printed it out in advance. ;)

    Check your:

    • PC network interface (eg. did someone unplug the network cable?)
    • Router
    • Modem
    • Is the modem still connected (eg. has a dial-up connection dropped out?)
    • If possible see if your ISP has announced technical problems. This is hard to do if you cannot use the Internet, but you could ring their help desk, or ring a friend and ask if they too are having problems.

    One thing to try is to "power cycle" (turn off, wait, and turn on again) all the relevant gadgets you have control over. I would start with the one furthest from the PC and work backwards. That is:

    • The modem
    • The router
    • The PC itself

    Doing this can clear transient problems that have occurred.

  2. Have you been able to connect to this game recently from this PC?

    If you have recently been playing this game (like, yesterday, or five minutes ago), then probably there is not an issue with router or firewall configuration. In this case, go to Step 3, below.

    However if you have never connected to this game from this PC, the problem may well be someone has set up a firewall or router configuration blocking online game access.

    This is particularly likely if you are at a school, college, or workplace. They may configure their router to let certain "ports" (like 80 for web browsing) go through, but block other ones.

    If you have never connected from this PC, first establish if the game is still up. If you played it an hour ago at home, then went to school, and now can't reach it, then probably there is a firewall issue. This may be impossible to resolve, and you may have to wait until you are back at home again.

    As suggested earlier, you could go to http://www.mudconnect.com/ and see if the game is currently up.

  3. I was playing the game five minutes ago and now I can't.

    If you have got down to Step 3: you were playing the game recently, and now you can't, however you can still browse the Internet, get mail, etc., then probably the game itself is down.

    This could be because:

    • The game simply crashed and is being rebooted - in which case it will be back shortly.

    • The game crashed, and is awaiting an admin to come and reboot it - in which case it may not be back for hours.

    • The game server had a hard disk crash - this may mean it will be down for days while they find another server and restore from backups (if any).

    • The game has been brought down permanently. Perhaps the admins got tired of running it, or couldn't pay the bill for the game server.

    • There has been a Denial of Service attack on the game server, or the nearby ISPs. This may result in the game being down until it can be resolved.

    • The game has been deliberately brought down for an hour for maintenance or backups.

    • The game has been deliberately brought down to install new features.

    • The game server has had to move to a new ISP (service provider) and this is taking a few days to do.

    • The game is still up, but you have been booted and banned for some in-game behaviour. If you find that you cannot connect a couple of minutes after insulting one of the admins, this may well be the case.

    Steps I would take to work out what is happening would be:

    • Wait half an hour, and then try to connect again.

    • Go to the game's web site. There may be an announcement, especially if there is expected to be a lengthy outage due to a crash, maintenance, site move, or installation of new features.

    • If the game runs a forum site, try that. Often forums are updated more quickly than "official" announcements.

    • Go to http://www.mudconnect.com/ and see if the game seems to be up using their "test game" feature.

    • Contact other players, if you know their phone numbers or email addresses. If another player says "I am still playing" that shows that the game is still up.

    • Check your email for a message from the game admins about the game going down for a while, or your character being banned.

  4. I keep getting disconnected

    Some routers have an "inactivity timeout" period set. This may be 5 minutes or so. Symptoms are that you get disconnected after playing for a while, but you can reconnect OK.


    • Configuring the router to disable "inactivity timeouts".

    • Install the "Config_Option_Changer" plugin which ships with MUSHclient (Config_Option_Changer.xml). Then use that to set the option "Send keep-alives" to "Yes". Then restart the client. This sends a special "keep-alive" packet every 2 minutes, which should tell the router to not disconnect you.

    • If that fails, try using a timer to send a non-intrusive command (like "look") to the MUD every couple of minutes.

- Nick Gammon

www.gammon.com.au, www.mushclient.com
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Posted by Nick Gammon   Australia  (23,017 posts)  [Biography] bio   Forum Administrator
Date Reply #3 on Wed 09 Jan 2008 08:50 PM (UTC)

Amended on Wed 09 Jan 2008 08:51 PM (UTC) by Nick Gammon

Proxy server to bypass firewalls

A post in this thread shows a method of getting past many firewalls (eg. at school, work) and still play your MUD:


Basically it involves downloading a special client that you connect to via MUSHclient. This (I gather) turns your communication with the MUD into what looks like normal http browser requests, and sends them out via the normal web browser port (this is configurable). The firewall would then think you are just browsing web pages.

You need to register to use this service:


Read the forum post mentioned above for more details. It is possible in the future this service won't be offered any more, and an alert site administrator could probably defeat it by disallowing any communication with their proxy server site.

- Nick Gammon

www.gammon.com.au, www.mushclient.com
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Posted by Nick Gammon   Australia  (23,017 posts)  [Biography] bio   Forum Administrator
Date Reply #4 on Thu 03 Jul 2008 02:26 AM (UTC)

Amended on Thu 03 Jul 2008 02:28 AM (UTC) by Nick Gammon

Another thing to try is tracert (trace route). This checks out each step of your internet connection, to see if something has failed in the middle.

To do this open a command window (Start Menu -> Run, and then type "cmd" and press <enter>).

For example, here is a successful trace to smaug.org:

C:\ > tracert smaug.org

traceroute to smaug.org (, 64 hops max, 40 byte packets
 1 (  1.761 ms  1.431 ms  1.435 ms
 2 (  8.155 ms  17.548 ms  8.026 ms
 3 (  16.704 ms  7.795 ms  12.258 ms
 4 (  7.254 ms  10.338 ms  9.760 ms
 5  CPE-61-9-133-8.vic.bigpond.net.au (  12.241 ms  7.405 ms  8.005 ms
 6  10GigabitEthernet4-1.win16.melbourne.telstra.net (  7.669 ms  9.506 ms  17.335 ms
 7  TenGigE0-8-0-5.win-core1.Melbourne.telstra.net (  9.388 ms  8.794 ms  10.358 ms
 8  Pos0-0-0-0.fli-core1.Adelaide.telstra.net (  19.812 ms  19.370 ms  19.794 ms
 9  Pos0-0-0-0.wel-core3.Perth.telstra.net (  52.132 ms  56.015 ms  49.686 ms
10  GigabitEthernetx-x.per-core02.Perth.net.reach.com (  49.686 ms  50.811 ms  50.207 ms
11  i-1-0.pthp-core01.net.reach.com (  52.702 ms  52.663 ms  52.183 ms
12  i-5-3.ntp-core02.net.reach.com (  101.178 ms  103.365 ms  105.608 ms
13  i-1-1-1.6ntp02.net.reach.com (  103.719 ms  100.273 ms  104.244 ms
14 (  103.204 ms  103.807 ms  103.262 ms
15 (  325.600 ms  329.834 ms  327.829 ms
16 (  325.061 ms  325.215 ms  326.379 ms
17  core4-ge60p.151.megarouting.com (  324.798 ms  328.077 ms  330.813 ms
18  core2-srp30p.300.megarouting.com (  333.127 ms  338.263 ms  333.979 ms
19  c6500-vl5.300.megarouting.com (  335.619 ms  333.324 ms  335.626 ms
20  smaug.org (  335.872 ms  335.119 ms  334.101 ms

Note the bottom line (line 20) shows we "arrived" at smaug.org.

And here is a less successful trace I did when I couldn't connect to a MUD:

C:\ > tracert 67.225.xxx.xxx

traceroute to 67.225.xxx.xxx (67.225.xxx.xxx), 30 hops max, 38 byte packets
1  router (  1.797 ms  1.691 ms  1.654 ms
2 (  10.034 ms  9.397 ms  7.781 ms
3 (  10.772 ms  9.186 ms  10.147 ms
4 (  9.850 ms  9.158 ms  9.940 ms
5  CPE-61-9-133-8.vic.bigpond.net.au (  9.724 ms  9.158 ms  10.189 ms
6  10GigabitEthernet4-1.win16.Melbourne.telstra.net (  10.216 ms  8.881 ms  12.406 ms
7  TenGigE0-8-0-5.win-core1.Melbourne.telstra.net (  9.346 ms  8.787 ms  9.601 ms
8  Bundle-Pos1.ken-core4.Sydney.telstra.net (  22.855 ms  22.197 ms  23.126 ms
9  Port-Channel1.pad-gw2.Sydney.telstra.net (  22.344 ms  21.997 ms *
10  10GigabitEthernet2-0.sydp-core02.Sydney.reach.com (  23.997 ms  24.768 ms  23.698 ms
11  i-9-0.sydp-core01.net.reach.com (  23.743 ms  22.363 ms  23.634 ms
12  i-14-0.wil-core03.net.reach.com (  213.391 ms  212.012 ms  212.204 ms
13  i-10-0.sjc-core01.net.reach.com (  185.133 ms  180.883 ms  181.206 ms
14  g4_4-sjc02.net.reach.com (  182.130 ms  181.201 ms  181.708 ms
15  ge-6-18.car4.SanJose1.Level3.net (  181.410 ms  182.789 ms  180.627 ms
16  vlan99.csw4.SanJose1.Level3.net (  182.601 ms  194.785 ms  181.201 ms
17  ae-92-92.ebr2.SanJose1.Level3.net (  187.658 ms  188.760 ms  181.282 ms
18  ae-3.ebr1.Denver1.Level3.net (  215.577 ms  216.700 ms  216.214 ms
19  ae-1-100.ebr2.Denver1.Level3.net (  214.492 ms  211.526 ms  216.532 ms
20  ae-3.ebr3.Chicago1.Level3.net (  241.943 ms  240.174 ms  235.021 ms
21  ae-78.ebr2.Chicago1.Level3.net (  235.972 ms ae-68.ebr1.Chicago1.Level3.net (  232.570 ms  243.208 ms
22  ae-11-53.car1.Chicago1.Level3.net (  234.540 ms  232.256 ms  231.934 ms
23  * * *
24  * * *
25  * * *
26  * * *
27  * * *
28  * * *
29  * * *
30  * * *

(Some parts of the address x-ed out for privacy).

Note how the trace seems to stop at the Level3 router in Chicago. This would appear to suggest that there are problems there.

Some system administrators configure their servers to reject ICMP packets (which is what tracert uses). So it is possible for a tracert to fail near the end of the trip, however the server is still up. Nevertheless, this is still a useful diagnostic tool. If you appear to have arrived "near" the appropriate server, then the network is probably up. If it fails near your end (in my case, if it stopped at the Sydney routers), then that would indicate a network problem.

There isn't much you can do about that, but wait until the appropriate parts of the network are fixed.

- Nick Gammon

www.gammon.com.au, www.mushclient.com
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Posted by Shadowfyr   USA  (1,786 posts)  [Biography] bio
Date Reply #5 on Thu 03 Jul 2008 06:03 PM (UTC)
Minor note on the blocking of ICMP packets, etc. One problem with the trace system is that it relies on a method to find the path that is "not" the same as the one you will actually use to talk to the server. I have found:

1. Cases where ICMP made it through, but the server won't respond at all to anything.
2. Cases where telnet seems to be blocked, but ICMP and HTTP work fine.
3. Cases where telnet works, but ICMP and HTTP are down (and I presume others).

Some servers seem to bring services back up in sequence, or their admin shut down all access for a time, then forget to bring one or more protocol handlers back up, which results in them staying blocked. Worst case I ever had of this was one obscure router in the middle of no place, which, because it was at the time the only "path" to the game, traced perfectly, let me HTTP to the games web page, **yet** never did allow me to telnet into the game, with the result that I had to wait for normal services to resume on the broken part of the network (and for the network to catch on to the fact that it could once more *use* that repaired path).

Unfortunately, all you can do in such cases is wait and hope they realize that something is still wrong. :(
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Posted by Cross_Marian   Spain  (5 posts)  [Biography] bio
Date Reply #6 on Thu 09 Apr 2009 01:44 PM (UTC)

Amended on Thu 09 Apr 2009 01:45 PM (UTC) by Cross_Marian

Is it possible to add for the ones who are running on localhost to have the remaining open ports checked? I found this applet on Google and thanks to it I saw what ports on my computer were open so to prevent the 10061 error on localhost. Now I can connect to my own little world at last. The site to the port scan is this one:


Hope this helps since it helped me.
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Posted by Nick Gammon   Australia  (23,017 posts)  [Biography] bio   Forum Administrator
Date Reply #7 on Sun 12 Apr 2009 11:09 PM (UTC)

Amended on Sun 12 Apr 2009 11:10 PM (UTC) by Nick Gammon

You can also open a "command" (console) window and type:

netstat -a

That shows ports Windows is using. Or try:

netstat -ab

That also shows what program is using the port. For example, on my computer:

Active Connections

  Proto  Local Address          Foreign Address        State           PID

  TCP    localhost:4000         localhost:0            LISTENING       2224

  TCP    localhost:3843         localhost:3844         ESTABLISHED     2896

  TCP    localhost:1066          ESTABLISHED     3076

That (pruned) output shows:

  • Smaug server is listening for connections on local port 4000
  • Firefox has an established connection on port 3844
  • MUSHclient has a connection to another of my MUD servers on

- Nick Gammon

www.gammon.com.au, www.mushclient.com
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