Client connection problem

Necron · Post by **Necron** » Thu Sep 22, 2005 3:34 am

Whenever a client with an unknown (uncached) IP connects, it gets up to
"*** Looking up your hostname..."
then stops. Then when you disconnect and connect again,
"*** Looking up your hostname..."
"*** Found your hostname (cached)"
and continues to connect to the irc.

I also commented out "show-connect-info;" in the conf, and it stops at
"There are x users and x invisible on x servers"

Is this a server problem? How can i fix it?

Cheers

w00t · Post by **w00t** » Thu Sep 22, 2005 5:19 am

Not.. at all sure what's going on :p

Sounds like DNS resolution isn't working properly, how's your /etc/resolv.conf?

Not sure on your second question.

Stealth · Post by **Stealth** » Thu Sep 22, 2005 5:52 am

This is due to DNS. You should have a valid server in your conf, with proper retries and timeout (the defaults work fine for retries/timeout). The reason the second connection works, is because your host is already cached (meaning Unreal already knows what it is from a previous lookup attempt). I have noticed this problem is common on IRCds which use 127.0.0.1 as their DNS server.

Unreal uses the DNS servers provided by the OS, and I don't know why 127.0.0.1 slows it down so much. Usually playing with the DNS settings, you can get it to run smoothly. Keep in mind that a restart of Unreal is required when changing its DNS settings. A rehash just doesn't do...

Necron · Post by **Necron** » Thu Sep 22, 2005 6:13 am

Stealth, you mean

Code: Select all

	dns {
		nameserver my.ip.goes.here;
		timeout 2s;
		retries 2;
	};

changed that and restarted, reconnected to the internet (dynamic IP) and it still stops there.

w00t, the /etc/resolv.conf looks right

Post by **Syzop** » Thu Sep 22, 2005 2:40 pm

Necron wrote:I also commented out "show-connect-info;" in the conf, and it stops at
"There are x users and x invisible on x servers"

You can manage to make them connect but get stuck there after the LUSERS stuff?? If that's true, then it's very odd, really... (and then dns cannot be the cause of it, perhaps not even unreal)
PMTU discovery comes to my mind, though that is just a hunch. In that case, be sure you are not blocking all ICMP traffic on the server.

What kind of server is it anyway? (Operating System, shell/server at home/dedicated server)

Anyway, if I ignore that other problem, and continue with this:

Whenever a client with an unknown (uncached) IP connects, it gets up to
"*** Looking up your hostname..."
then stops. Then when you disconnect and connect again,

How do you disconnect... Do you get an error / quit message? What exact disconnect message is it?

* offtopic... *

I have noticed this problem is common on IRCds which use 127.0.0.1 as their DNS server.

Actually, if you run your own caching nameserver, such as bind or dnscache on 127.0.0.1, then you got the fastest nameserver setup there is ;P. (Assuming it's configured correctly, iotw: you use forwarding nameservers and not the root nameservers). This happens to be my setup ;)

Necron · Post by **Necron** » Thu Sep 22, 2005 3:06 pm

when i comment out show-connect-info, it freezes after the first line of lusers, doesnt show the rest.

i have to disconnect the client when it stops, i left it for about 10 minutes and it just stood there. the logs said i connected and dc'd, nothing else.

the server is a mates, all i know is it's on a *nix platform and its a server at home

Suchiara · Post by **Suchiara** » Thu Sep 22, 2005 6:24 pm

sorry for offtopic, but is using dns 127.0.0.1 on loaded servers bad idea?
I mean, I can replace 127.0.0.1 with the external ip of my host (the localhost), would it help? Or do you mean that using dns on the same machine where ircd is bad?

Matridom · Post by **Matridom** » Thu Sep 22, 2005 6:31 pm

Suchiara wrote:sorry for offtopic, but is using dns 127.0.0.1 on loaded servers bad idea?
I mean, I can replace 127.0.0.1 with the external ip of my host (the localhost), would it help? Or do you mean that using dns on the same machine where ircd is bad?

when under a dos attack, you change the DNS to point to 127.0.0.1, change your IP.

the ddos attack will loose track of the IP, will resolve the DNS anew trying to get the new IP and find 127.0.0.1, the bots then attack that (themselves)

if it's a small network, it's fairly easy to tell people individualy the new IP for the server or if your lucky and have a second unaffected server people tend to move over.

Post by **Syzop** » Thu Sep 22, 2005 7:56 pm

Suchiara / Matridom:
I think we are getting things mixed up here ;). (Naturally Icould it read wrong too, but..): Suchiara means if using 127.0.0.1 as a nameserver (so in /etc/resolv.conf) is good or bad.
Answer is: it can be very good, because your local bind/dnscache/whateverdnsserver can cache things correctly, and I would actually recommend such a setup. There are not many downsides I can think of, except that you run another program ;).
It's usually a good idea, however, to specify your ISP nameservers in options::forwarders in BIND, other nameservers (eg: 'dnscache') might have a similar option

Necron:
I would suggest trying my icmp idea...
Best would be to, if your mates server has an web or ftp server too, to download a large file from that server via http/ftp (1-5mb would be fine), and see if that goes succesfull.
If that went ok, ignore my icmp/(P)MTU story.
If that did not went ok, it would confirm a (P)MTU problem.
These issues are rare though, but it's just the only thing I can think of right now.

Stealth · Post by **Stealth** » Thu Sep 22, 2005 8:01 pm

Syzop wrote:Actually, if you run your own caching nameserver, such as bind or dnscache on 127.0.0.1, then you got the fastest nameserver setup there is ;P. (Assuming it's configured correctly, iotw: you use forwarding nameservers and not the root nameservers). This happens to be my setup

Yes, localhost nameservers are great, but many people dont have them and just put 127.0.0.1 in set::dns::nameserevr, which for some reason slows Unreal in some cases...

Necron · Post by **Necron** » Thu Sep 22, 2005 11:20 pm

Syzop wrote:I would suggest trying my icmp idea...
Best would be to, if your mates server has an web or ftp server too, to download a large file from that server via http/ftp (1-5mb would be fine), and see if that goes succesfull.
If that went ok, ignore my icmp/(P)MTU story.
If that did not went ok, it would confirm a (P)MTU problem.
These issues are rare though, but it's just the only thing I can think of right now.

Didnt have a problem downloading from the server, he uses it as his daily webserver and hasnt had any problems.

Post by **Syzop** » Thu Sep 22, 2005 11:22 pm

Stealth wrote:Yes, localhost nameservers are great, but many people dont have them and just put 127.0.0.1 in set::dns::nameserevr, which for some reason slows Unreal in some cases...

I really doubt it :P. Unless it mysteriously shows up in '/quote dns i'.

Didnt have a problem downloading from the server, he uses it as his daily webserver and hasnt had any problems.

Large file? ok
I've no idea then.

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