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420 lines
18 KiB
420 lines
18 KiB
This is the readme to the Lan Information Server LISa and the Restricted LAN
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Information Server resLISa.
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+---------------+
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| LISa |
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+---------------+
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LISa is intended to provide a kind of "network neighbourhood" but only
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relying on the TCP/IP protocol stack, no smb or whatever.
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It is completely independent from KDE/Qt.
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The list of running hosts is provided via TCP port 7741.
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LISa supports two ways of finding hosts:
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1. you give LISa a range of of IP-addresses, then LISa will send
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ICMP echo requests to all given IP addresses and wait for the answers
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2. you can say LISa to execute "nmblookup "*" ", i.e. the command line tool
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nmblookup must be installed, it is part of the samba package.
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nmblookup "*" sends a broadcast to the attached networks and all hosts
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running smb-services will answer this broadcast
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lisa and reslisa are distributed under the GNU General Public License.
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How it works
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-------------
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In the configuration file you provide a range of IP-addresses which
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LISa should check, wether they are running. In the most simple case
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this could be your network address/subnetmask, then LISa would
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check every possible host of your network wether it is running.
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The hosts are checked using ICMP echo requests. To be able to send and receive
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ICMP echo requests and replies the program has to open a so-called
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"raw socket". Therefor it needs root privileges. This socket is opened
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right after the start of the program, after successfully opening the socket
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root privileges are dropped immediately (see main.cpp and strictmain.cpp).
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If you configure LISa this way, that it also uses nmblookup, it will
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popen("nmblookup \"*\"") and then parse the results.
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Since the ICMP requests and the broadcasts can cause some network traffic
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if there are more than one such server running in one network, the servers
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cooperate with each other. Before they start pinging (or nmblookup),
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they send a broadcast on port 7741.
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If somebody answers this broadcast, they will retrieve the complete list
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of running hosts via TCP port 7741 from this host and will not start to
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ping (or nmblookup) theirselves. If nobody answers, the host which sent
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the broadcast will start pinging the hosts (or nmblookup) and then open a
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socket which listens for the mentioned broadcasts. If the host received an
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answer to his broadcast, it won't have the socket for listening to the
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broadcasts open. So usually exactly one of the servers will have this
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socket open and only this one will actually ping (or nmblookup) the hosts.
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In other words, the servers are lazy, they work like "I will only do something
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if nobody else can do it for me".
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There is another feature which reduces the network load. Let's say you configured LISa
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to update all 10 minutes. Now you don't access your server very often.
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If nobody accesses the server for the last update period, the server will
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update (either itself or from the one which actually does the work) and then
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double its update period, i.e. the next update will happen after 20 minutes.
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This will happen 4 times, so if nobody accesses the server with update period
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10 minutes for a long time, its update interval will increase up to
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160 minutes, almost three hours. If then somebody accesses the data from the
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server, he will get an old list ( up to 160 minutes old). With accessing
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the server will reset its update interval to its initial value,
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i.e. 10 minutes and immediately start updating if the last update is more
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than these 10 minutes over. This means if you get a very old list, you can try
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some seconds later again and you should get a current version.
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This will have fast effect for the servers, which don't ping (or nmblookup)
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theirselves, since only one user usually accesses them, and it will have
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less effect for the server which does the pinging (or nmblookup), since
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this server is accessed from all other servers in the network.
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This way it is possible that many hosts in a network run this server, but
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the net load will remain low. For the user it is not necessary to know
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wether there is a server (i.e. a name server or fileserver or whatever)
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in the network which also runs LISa. He can always run LISa locally
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and LISa will detect if there is one, transparently to the user.
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The first client for LISa is an ioslave for KDE2, so the user
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can enter there lan://localhost/ or lan:/, which will both
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contact LISa on the own system.
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If there is a machine which runs all the time and the user knows
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that this machine also runs LISa, he can use his LISa client directly with
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this server (would be with the mentioned ioslave lan://the_server_name/).
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If you don't want that your LISa takes part in the broadcasting, but always
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does the pinging itself, make it use another port with the
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command line option --port or -p.
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This is not recommended !
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If you send SIGHUP to LISa, it will reread its configfile.
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If you send SIGUSR1 to LISa, it will print some status information to stdout.
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The data provided over the socket has a simple format:
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<decimal ip address in network byte order><one space 0x20><full name of the host><a terminating '\0'><newline '\n'>
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and the last line
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0 succeeded<'\n'>
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e.g.
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"17302538 some_host.whatever.de
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18285834 linux.whatever.de
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17827082 nameserver.whatever.de
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0 succeeded
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"
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This should make it easy parseable.
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If there are very strict security rules in your network, some people
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might consider the pinging a potential attack. If you
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have problems with this, try the restricted version, resLISa.
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+------------------+
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| resLISa |
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+------------------+
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If you hav very strict security rules in your network or you don't want to
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have another port open or whatever, you can use resLISa.
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With resLISa you can't ping whole networks and address ranges, you can give
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resLISa up to currently 64 hosts by their names in its config file. These
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will be pinged. You are still able to use nmblookup.
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resLISa will also only provide the information over a unix domain socket, i.e.
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not over the network. The name of the socket is "/tmp/resLisa-YourLoginname",
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so resLISa can be safely run by more users on one machine.
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Since it should also not produce a security risk of any kind it is
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safe to install reslisa setuid root. root privileges will be dropped
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right after startup (see strictmain.cpp), they are only needed to create a raw socket
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for sending the ICMP echo requests..
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It will also not send or receive broadcasts.
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The first client for this is also an ioslave for KDE2 (makes rlan:/ in e.g. konqy).
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Configuration
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-------------
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Now an example config file:
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PingAddresses = 192.168.100.0/255.255.255.0;192.168.100.10-192.168.199.19;192.168.200.1;192-192.168-168.100-199.0-9;
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PingNames = bb_mail;
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AllowedAddresses = 192.168.0.0/255.255.0.0
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BroadcastNetwork = 192.168.100.0/255.255.255.0
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SearchUsingNmblookup = 1 #also try nmblookup
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FirstWait = 30 #30 hundredth seconds
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SecondWait = -1 #only one try
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#SecondWait = 60 #try twice, and the second time wait 0.6 seconds
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UpdatePeriod = 300 #update after 300 secs
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DeliverUnnamedHosts = 0 #don't publish hosts without name
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MaxPingsAtOnce = 256 #send up to 256 ICMP echo requests at once
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PingAddresses
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This is probably the most important entry.
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Here you say which addresses will be pinged. You can specify multiple
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ranges, they are divided by semicolons.
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There are four possible ways to define addresses:
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-net address/network mask: 192.168.100.0/255.255.255.0, i.e. an IP address
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and the assigned network mask. This doesn't have the real network address
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and netmask of your machine, it can be less. E.g. if you have
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10.0.0.0/255.0.0.0, you could specify 10.1.2.0/255.255.255.0 if you are only
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interested in these addresses. The combination IP address-network mask
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must be divided by a slash "/" and the address does not have to be a real
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network address, it can also be a host address of the desired network,
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i.e. 10.12.34.67/255.0.0.0 is the same as 10.0.0.0/255.0.0.0 .
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-a range of following IP addresses: 192.168.100.10-192.168.199.19, i.e.
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an IP-address where pinging will start and an IP-address where pinging will end.
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Both addresses must be divided by a "-".
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In this example this would produce 199-100+1=100, 100*256=25.600,
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25.600+(19-10+1)=25.590 addresses
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-an IP-address can be presented by its four decimal numbers, you can specify
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ranges four each of these four numbers: 192-192.169-171.100-199.0-9
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In this example all IP addresses with first number 192, second number from
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168 to 168, third number from 100 up to 199 and last number from 0 up
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to 9 will be pinged. This would give 1*1*100*10=1.000 addresses.
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This is probably only useful in very seldom cases.
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Here you have to provide ranges for every four numbers, always divided
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by "-".
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-single IP-addresses: 192.168.200.1
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well, single IP addresses or host names
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It is also valid to leave this entry empty.
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PingNames
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here you can additionally specify hosts to ping using their names.
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The names have to be divided by semicolons.
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It is also valid to leave this entry empty.
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AllowedAddresses
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This is also very important. LISa will only ping addresses,
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accept clients and answer broadcasts from addresses, which are covered by the
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addresses given in this line. You can add up to 32 network addresses/network masks
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or single addresses. Divide them by ; and don't put empty space between the
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addresses !
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Example: 192.168.0.0/255.255.0.0;192.169.0.0
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-> a complete network and a single address are valid
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Always make this as strict as possible, usually
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your network address/subnetmask is a good choice.
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BroadcastNetwork
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This entry contains exactly one network address/subnet mask.
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To this network broadcasts will be sent. Usually this should be your
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own network address/subnetmask.
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Example: 192.168.0.0/255.255.0.0
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SearchUsingNmblookup
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Here you can give 0 or 1.
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1 means that LISa will execute "nmblookup "*" " and parse the output
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from this command. This produces less network traffic than the pinging,
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but you will only get hosts which have a smb-service running (Windows
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machines or machines running samba).
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If you enable this option and also give IP addresses to ping, then nmblookup
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will be executed first and then the pinging will start.
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Then only addresses will be pinged, which were not already delivered
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from nmblookup. This should slightly decrease the network load.
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FirstWait
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If LISa pings, i.e. if it sends the ICMP echo requests, it sends a bunch
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of requests at once, and the it will wait for the number of hundredth seconds
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you specify here. Usually values from 5 to 50 should be good, the maximum
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is 99 (gives 0.99 seconds, a very long time).
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Try to make this value as small as possible while still finding all
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running hosts.
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SecondWait
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After LISa sent the echo requests the first time, it can be possible
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that some hosts were not found. To improve the results, LISa can ping a
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second time. This time it will only ping hosts, from which it didn't receive
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answers. If you have good results with pinging only once, you can disable
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the second time with setting SecondWait to -1.
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Otherwise it might be a good idea to make this value a little bit bigger
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than the value for FirstWait, since the hosts which were not found
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on the first try, are probably slower or further away so they might take
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some milliseconds longer to answer.
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Usually values from 5 to 50 should be good or -1 to disable the second scan.
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The maximum is 99 (gives 0.99 seconds, a very long time).
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UpdatePeriod
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This is the interval after which LISa will update, i.e. ping or nmblookup
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or get the list of hosts from the LISa server which actually does the pinging.
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Valid values are between 30 seconds and 1800 seconds (half an hour).
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If you have a big network, don't make the interval to small (to keep
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network load low). Values from 300 to 900 seconds (5 to 15 minutes) might be
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a good idea. Keep in mind that the update period is doubled
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if nobody accesses the server, up to 4 times, so the interval will become
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16 times the value given here and will be reseted to the value given here
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if somebody accesses the server.
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DeliverUnnamedHosts
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If an answer to an echo request from an IP address was received, were LISa
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could not determine a name, it will be only delivered over the port
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if you set this to 1.
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I am not really sure if this is a useful feature, but maybe
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there are some infrastructure devices in your network without assigned names,
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so they don't have to be published. Set this to 0 if you want to keep them
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secret ;-)
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If unsure, say 0.
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MaxPingsAtOnce
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When sending the pings (echo requests), LISa sends a bunch of these at once
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and then waits for the answers. By default there are 256 pings sent at once,
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usually you should not need the change this value. If you make it much bigger,
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the internal receive buffers for the answers to the echo requests may become to small,
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if you make it to small, the updating will be slower.
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Three different example config files:
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You are member of a small network with 24 bit network mask, i.e.
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up to 256 hosts:
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PingAddresses = 192.168.100.0/255.255.255.0
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AllowedAddresses = 192.168.100.0/255.255.255.0
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BroadcastNetwork = 192.168.100.0/255.255.255.0
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SearchUsingNmblookup = 0 #don't use nmblookup
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FirstWait = 20 #20 hundredth seconds
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SecondWait = 30 #30 hundredth seconds on the seconds try
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UpdatePeriod = 300 #update after 300 secs
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DeliverUnnamedHosts = 0 #don't publish hosts without name
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You are only interested in hosts running smb services and you don't have
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routers in your network:
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AllowedAddresses = 192.168.100.0/255.255.255.0
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BroadcastNetwork = 192.168.100.0/255.255.255.0
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SearchUsingNmblookup = 1 #use nmblookup
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UpdatePeriod = 300 #update after 300 secs
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DeliverUnnamedHosts = 0 #don't publish hosts without name
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The same network, but here both nmblookup and pinging is used.
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PingAddresses = 192.168.100.0/255.255.255.0
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PingNames = bb_mail
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AllowedAddresses = 192.168.0.0/255.255.0.0
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BroadcastNetwork = 192.168.100.0/255.255.255.0
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SearchUsingNmblookup = 1 #also try nmblookup
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FirstWait = 30 #30 hundredth seconds
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SecondWait = -1 #only one try
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#SecondWait = 60 #try twice, and the second time wait 0.6 seconds
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UpdatePeriod = 300 #update after 300 secs
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DeliverUnnamedHosts = 0 #don't publish hosts without name
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MaxPingsAtOnce = 256 #send up to 256 ICMP echo requests at once
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And now a configuration file for resLISa, PingAddresses is not used by resLISa,
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neither is BroadcastNetwork.
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PingNames = bb_mail;some_host;some_other_host
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AllowedAddresses = 192.168.0.0/255.255.0.0
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SearchUsingNmblookup = 1 # use nmblookup
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FirstWait = 30 #30 hundredth seconds
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SecondWait = -1 #only one try
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#SecondWait = 60 #try twice, and the second time wait 0.6 seconds
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UpdatePeriod = 300 #update after 300 secs
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DeliverUnnamedHosts = 1 #also publish hosts without name
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MaxPingsAtOnce = 256 #send up to 256 ICMP echo requests at once
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+----------------------+
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| Installation |
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+----------------------+
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Both reslisa and lisa open a so called raw socket to send and receive
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ICMP echo requests (pings). To do this, they need root privileges.
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lisa offers a service on TCP port 7741, it should be installed by root
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and started when the system comes up, it depends on your distribution
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how to do this.
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reslisa is intended to be started per user, it doesn't offer anything to
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the network. It needs to be installed setuid root.
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If you use the rlan-ioslave from KDE2, reslisa can be started automatically
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by reslisa.
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lisa reads the file lisarc, reslisa reads the file reslisarc.
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If you want to be able to configure both from the TDE Control Center,
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you have to start them using the command line switch -K.
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For more information where they look for configuration files read
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the next chapter.
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+--------------------------------------------+
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| Command Line Options and other usage |
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+--------------------------------------------+
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The following command line options are supported:
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-v, --version prints a short version info
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-h, --help gives an overview over teh command line options
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Some options regarding search order for the configuration files.
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For reslisa the file is named reslisarc instead lisarc.
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-u, --unix search at first for $HOME/.lisarc, then
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for /etc/lisarc, this is the default behaviour
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-k, --kde1 search at first for $HOME/.trinity/share/config/lisarc,
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then for $TDEDIR/share/config/lisarc
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-K, --kde2 looks for the file lisarc in every directory
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returned by running "tde-config --path config"
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-c, --config=FILE read this and no other configuration file
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This one is only available for LISa, not for resLISa.
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-p, --port PORTNR start the server om this portnumber
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if you use this LISa won't be able to
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cooperate with other LISa's in the network
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If you send the Hangup-Signal to lisa or reslisa, it will reread its
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configuration file (killall -HUP lisa).
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If you send the User1-Signal to lisa or reslisa, it will print some status
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information to the standard output (killall -USR1 lisa). You won't see
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anything if the console from which lisa/reslisa was started has terminated.
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LISa and resLISa need a libstdc++ (it uses only the string-class from it),
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it *doesn't* need neither Qt nor KDE.
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So, that's it for now.
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If you have suggestions, problems or whatever, contact me.
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Have fun
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Alexander Neundorf
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<neundorf@kde.org>
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