Re: imap problem with blackhole

2006-02-28 Thread Nikos Vassiliadis
On Sunday 26 February 2006 14:26, Perttu Laine wrote:
 Hello!

 I have problem with imap. Works fine if blackhole (tcp) is set to 0, but I
 set it 1 or 2 imap stops responding (timeouts). Dovecot imap and freebsd
 5.4. So. What could be case here?

I suspect that it's trying to do something to localhost and doesn't get a
reply back. Many programs behave like that, in my case kmail. It was
trying to use rpc, other programs try to use ident. So, first find out what
it's trying to do, use netstat -nafinet and you'll see some some TCP sockets
in SYN_SENT state, for example:

nik:0:~$ telnet 127.1 
[1] 75027
nik:1:~$ Trying 127.0.0.1...
netstat -nafinet
Active Internet connections (including servers)
Proto Recv-Q Send-Q  Local Address  Foreign Address(state)
tcp4   0  0  127.0.0.1.56239127.0.0.1.23   SYN_SENT
[...]

telnet will time out eventually. The kernel never sends a TCP reset
there 'cause tcp.blackhole=1

step 2, use your favorite firewall to return an active reply(TCP reset),
in my case:

root:0:~# pfctl -srules
No ALTQ support in kernel
ALTQ related functions disabled
block return in inet proto tcp from 127.0.0.1 to 127.0.0.1 port = sunrpc
block return in inet proto udp from 127.0.0.1 to 127.0.0.1 port = sunrpc
block drop in log inet proto tcp from any to any port 6000:6010 flags S/SA
root:0:~# 

perhaps in a more complex situation(UDP) you should use a packet filter
to log everything that goes through the loopback interface. Are you using
TCP AND UDP blackhole?

HTH, Nikos


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imap problem with blackhole

2006-02-26 Thread Perttu Laine
Hello!

I have problem with imap. Works fine if blackhole (tcp) is set to 0, but I
set it 1 or 2 imap stops responding (timeouts). Dovecot imap and freebsd 5.4.
So. What could be case here?

--
kpn @ IRCnet
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Re: imap problem with blackhole

2006-02-26 Thread Kees
Perttu Laine wrote on Sunday 26 February 2006 13:26:

 Hello!
 
 I have problem with imap. Works fine if blackhole (tcp) is set to 0, but I
 set it 1 or 2 imap stops responding (timeouts). Dovecot imap and freebsd
 5.4. So. What could be case here?

Strange, I use FreeBSD-5.4 and dovecot with imap as well, but it works fine
after setting net.inet.tcp.blackhole=1.
Perhaps your mailclient reads a (wrong) closed port and hangs after not
receiveing a rst-packet ?

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Re: imap problem with blackhole

2006-02-26 Thread Perttu Laine
On 2/26/06, Kees [EMAIL PROTECTED] wrote:


 I have problem with imap. Works fine if blackhole (tcp) is set to 0, but I
  set it 1 or 2 imap stops responding (timeouts). Dovecot imap and freebsd
  5.4. So. What could be case here?
 Strange, I use FreeBSD-5.4 and dovecot with imap as well, but it works
 fine
 after setting net.inet.tcp.blackhole=1.
 Perhaps your mailclient reads a (wrong) closed port and hangs after not
 receiveing a rst-packet ?


Well it's same with every client (thunderbird, oe, the bat, nokia 9300
communicator) and even squirrelmail webmail which is on same machine.

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Re: imap problem with blackhole

2006-02-26 Thread Perttu Laine
Oh damn. It was problem with dummy sysadmin only (me). I tried to connect
localhost instead of real hostname and dovecot didn't answer there. So. You
all can forget earlier posts. :)



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Re: imap problem with blackhole

2006-02-26 Thread Kees
Perttu Laine wrote on Sunday 26 February 2006 14:37:

 Oh damn. It was problem with dummy sysadmin only (me). I tried to connect
 localhost instead of real hostname and dovecot didn't answer there. So.
 You all can forget earlier posts. :)
 

I have a bad memory anyway :-)




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