[Sheflug] Networking

[Barrie Bremner <xxxxx [at] xxxxxxxxxxxxxxxxx>]

Sorry about this - I'm hopeless at explainly anything :-)

>>>>> "Llewelyn" == richard davies <llewelyn.davies [at] eudoramail.com> writes:

    Llewelyn> Hi, First thank you for all the help you have already
    Llewelyn> given me on various problems and now for something new.

    Llewelyn> I am just experimenting with networking and have the
    Llewelyn> following set up

    Llewelyn> computer one Mandrake 7.2 mysystem.downstairs

    Llewelyn> computer two Mandrake 8.0 mysystem.upstairs

    Llewelyn> They are both set with hosts.allow = ALL: hosts.deny =
    Llewelyn> NONE

Assuming you're just testing, /etc/hosts.allow should be

ALL: ALL

/etc/hosts.deny shouldn't make any difference, because hosts.allow is
checked first, and you told the system to allow everyone, but it
should be empty (comments are OK.)

    Llewelyn> I can ping from either box from downstairs I can telent,
    Llewelyn> ssh, ftp to upstairs with no problems. Going the other
    Llewelyn> way I get connection refused by remote host what
    Llewelyn> configuration files do I need to look in to sort this
    Llewelyn> out. I have read the networking howto and am still
    Llewelyn> confused.

Connection refused _might_ not be anything to do with the access rights
(hosts.allow/deny, packet filtering etc) - check if the servers are
running on the machine that is causing the problems (the downstairs
box).

Are there any firewall rules on either boxen blocking connections?

As root, try ipchains -L -n or iptables -L -n to check.

SSH gives "secure connection to some.computer refused" if the network
is down or there is no SSH server listening on the far end (or a
firewall is blocking access).

ps -aux | grep sshd

should give something like:

[baz@flux baz]$ ps -aux | grep sshd
root       667  0.0  0.3  2676 1272 ?        S    Oct28   0:02 /usr/sbin/sshd
baz        870  0.0  0.1  1732  600 pts/5    S    23:31   0:00 grep sshd

/usr/sbin/sshd is the SSH server on my machine.

FTP and telnet are normally run from inetd or xinetd, have a look at
/etc/inetd.conf or /etc/xinetd.d/ - check that inetd or xinetd is
running (try ps -aux | grep inetd)

Uncomment the lines for the services you want to run in
/etc/inetd.conf, or look at the config files in /etc/xinetd.d and
check that the "disable =" bit is "disable = no" for services you want
to run.
(Re)start the service - there are scripts in /etc/init.d or
/etc/rc.d/init.d/ (depends on your system) to do this:

e.g.

/etc/rc.d/init.d/xinetd start
/etc/rc.d/init.d/xinetd restart
/etc/rc.d/init.d/xinetd stop

Are you getting a prompt for a user's password, or does everything
just come back connection refused?

    Llewelyn> Also when the local network is up I am unable to
    Llewelyn> download my mail from the web I have to close it first
    Llewelyn> and then dial into the web. I presume that my network
    Llewelyn> configurating is preventing the system using resolv.conf
    Llewelyn> to find the nameservers.  Why and what do I do about it?

Not sure on this on - /etc/resolv.conf generally gets updated when
you dialup, but IIRC the system shouldn't change it when an ethernet
connection comes up - my boxen certainly don't.

Usual check for nameserver problems:

dial up
have a look at /var/log/messages and /etc/resolv.conf
launch favourite web browser
http://194.247.47.86/
http://www.sheflug.co.uk/

should be the same site. If http://194.247.47.86/ works, but
http://www.sheflug.co.uk/ didn't, then something is wrong with DNS.

If nothing worked, you've got more problems :-)

Cheers.

Baz.

-- 
Barrie J. Bremner		OpenPGP public key ID: 5164F553
baz [at] barriebremner.com	http://barriebremner.com/


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