Linux Forums - Linux Networking

iptables - adding a 2nd subnet for WiFi?

dhumble — Fri, 20 Nov 2009 13:20:59 GMT

Hi,

My LAN is 192.168.160.0
I have a Draytek router 192.168.160.1 and I DMZ to my
Ubuntu 9.10 Server (2.6.31-14-generic-pae) which I run a few services on.

I have just added a Wireless Card 192.168.3.1, installed DHCPd and HOSTAPd, creating a 2nd subnet 192.168.3.0. The card is working fine as an AP and I now need assistance with adding filtering to IPTABLES.

I want wireless peers to be able to get a DHCP address and to access my LAN and the internet.

Help with setting up the filtering, and I believe MASQuerading would be appreciated.

David

Ping by Hostname

sputniks — Fri, 20 Nov 2009 07:45:36 GMT

Two linux (Redhat) computers are connected to an ordinary DSL router which runs DHCP service.
A router dynamically assigns 192.168.1.100 IP address to the first computer (hostname DENVER). And
another machine (hostname DALLAS) is assigned 192.168.1.101.
The router's settings (site accessed via 192.168.1.1) shows both of those computers listed with their corresponding hostnames and IP addresses:

Connection Type: Ethernet
PC Name: DENVER
IP Address: 192.168.1.100
MAC Address: 00:1b:63:ac:45:df

Connection Type: Ethernet
PC Name: DALLAS
IP Address: 192.168.1.101
MAC Address: 00:19:d1:9f:8d:52

I can ping both machines using their corresponding IP addresses: "ping 192.168.1.100" and "ping 192.168.1.101". That works great.
The problem occurs when I try to ping them using their hostnames instead of their ip addresses. They even don't respond to PING command if I ping the machine with its own name!
I went ahead and "hard coded" (typed) the combination of host names and their ip addresses into the each computer's /etc/hosts configuration files:

192.168.1.100 DENVER.mynetwork DENVER
192.168.1.101 DALLAS.mynetwork DALLAS

To my surprise that fixed one computer. But only one computer.... another is still not reachable by hostname.
I forgot to mention that both computers running a very basic fresh all-by- default Redhat Linux install... meaning no dns servers or dhcp servers or other additional servers or services were installed yet.... Should I stop using DSL Router's DHCP server? Should I instead install Linux's DHCP server on one of the computers and run DHCP server on a computer?
Thanks in advance for any suggestions!

Minimising WAN response times

johnlon — Thu, 19 Nov 2009 00:29:08 GMT

I have a client / server app.
Client server calls are made only when the user runs a query.
The client request is approx 100KB and the server response is about the same size.
Some background is that the client app currently hits a server that is in the same region globally. Therefore the impact of the network on response times is minimal. However I would like to retire the regional servers and instead have all global trafiic comming to a single server instance in London.
In this case many of my clients would be making WAN round trips.

My target response time for the round trip from a client app in Singapore to the server in London is sub-second for a 100K message to the server and a 100k message back to the client.

I did a few experiments using TCP and UDP with the client in Singapose and the Server in London.
FYI RTT from ping was 200ms.

With a TCP client/server it was taking 1.5 seconds from the moment the client started sending its query to the last read() of the response completing.

When I did a similar test using UDP the response time was about 205ms, which is close to the RTT.

Does the 1.4sec TCP round trip seem reasonable or is it likely I've not tuned TCP adequately - is so then what should I be looking at?

Now I understand that UDP is unreliable and thats bad for my application but at the same time the 1.5 seconds TCP timing is a killer for the responsiveness of my app across the WAN.

What if anything are my options to reduce the response times in this scenario?

FYI the TCP client/server had their SO_SNDBUF/SO_RCVBUF set to 1MB.
What I noticed for TCP across the WAN was that for a single 100KB send() by the client call I got lots of small reads (mostly 1.4KB but some a lot bigger) at the server.

I noticed that the UDP client was able to send data grams up to about 60K (I think there is a 64K limit), so I had to send a couple to handle 100KB.
One option I had considered with UDP reliability was sending the pair of datagrams from the client to the server then after a short delay of say 50ms send them again just in case the first pair didn't make it, then if the client doesn't get it's response within say 400ms of the start then try one more time before giving up.
If this all fails then give the user an error message about the network being down.
The hope here is that 99.99% of the time one of the three attemps will succeed and so I get response times between 200 and 600ms.
This is still well short of the 1.4 seconds I get from TCP.
But I have no idea whether this approach is likely to be at all reliable - how many attempts to send a UDP datagram does one need to make before one is likely to be successful and how many attempts does one need to make befor it's worth giving up and signalling a comms error?

I was really hoping that the 'simpler' TCP approach would give response times that were closer to the RTT. And to be honest all that adhoc reliability stuff I describe above is a pain.

If UDP is a sensible option for my use case - ie occasional 100KB round trips across the WAN - then does anyone have any advice on making it more reliable?

Do things like UDT help here? www .cs.uic.edu /~ygu1/]UDT Manual

All help / advice appreciated.

installed wvdial..but prob in installing usb modem

linux_pathak — Wed, 18 Nov 2009 17:36:07 GMT

PLSSSSSSSSSSSSSSSSS REPLYYYYYYYYYYYYYYYYYYYYYYYYY
M A UBUNTU 9.10 USER
guies...i manged to installed wvdial
but there is problem in installing tata indicom wireless usb modem..
when i typed wvdialconf/etc/wvdial.conf...notjing happened it didnt detected directory
but when i typed wvdialconf,,,following is the output...

omi@omi:~$ wvdialconf
Editing `/etc/wvdial.conf'.

Scanning your serial ports for a modem.

Modem Port Scan<*1>: S0 S1 S2 S3
WvModem<*1>: Cannot get information for serial port.
ttyACM0<*1>: ATQ0 V1 E1 -- OK
ttyACM0<*1>: ATQ0 V1 E1 Z -- OK
ttyACM0<*1>: ATQ0 V1 E1 S0=0 -- OK
ttyACM0<*1>: ATQ0 V1 E1 S0=0 &C1 -- OK
ttyACM0<*1>: ATQ0 V1 E1 S0=0 &C1 &D2 -- OK
ttyACM0<*1>: ATQ0 V1 E1 S0=0 &C1 &D2 +FCLASS=0 -- OK
ttyACM0<*1>: Modem Identifier: ATI -- ERROR
ttyACM0<*1>: Speed 4800: AT -- OK
ttyACM0<*1>: Speed 9600: AT -- OK
ttyACM0<*1>: Speed 19200: AT -- OK
ttyACM0<*1>: Speed 38400: AT -- OK
ttyACM0<*1>: Speed 57600: AT -- OK
ttyACM0<*1>: Speed 115200: AT -- OK
ttyACM0<*1>: Speed 230400: AT -- OK
ttyACM0<*1>: Speed 460800: AT -- OK
ttyACM0<*1>: Max speed is 460800; that should be safe.
ttyACM0<*1>: ATQ0 V1 E1 S0=0 &C1 &D2 +FCLASS=0 -- OK

Found an USB modem on /dev/ttyACM0.
Modem configuration written to /etc/wvdial.conf.
/etc/wvdial.conf: Can't write '/etc/wvdial.conf.tmp2602': Permission denied
/etc/wvdial.conf: Can't write '/etc/wvdial.conf' ('/etc/wvdial.conf'): Bad file descriptor
ttyACM0: Speed 460800; init "ATQ0 V1 E1 S0=0 &C1 &D2 +FCLASS=0"

but after this when i typed gedit/etc/wvdial.conf..
it says bash:no such directory...(something like that)..

can u guide me

[SOLVED] Network unreachable: cannot ping router

imranka — Mon, 16 Nov 2009 05:22:22 GMT

problem:

Trying to ping router 192.168.1.1, saying network unreachable (or not reachable, forgot exact word).

doing

Code:

dmesg | grep eth | less

Returning at the last a line like: no ipv6 router present.

Doing

Code:

lspci -vv | grep -i eth

Returning the Intel ethernet card that I have.

Doing

Code:

/sbin/ifconfig -a

doesn't return any inet , bcast, mask addresses.

Now, first I thought the ethernet cable was not working, so I took my router and the cable and connected in other person's machine, but there the router page opened properly. Now, he told me, that the lancard may got fried. Another person told me to check the etherent port.

Now, I am very confused, how to troubleshoot this? Biggest problem is that, I don't have internet by my side to check immediately this forums or anything.

Any suggestion please....

Cisco VPN Client compatible with FVS318 V3

zillah — Mon, 16 Nov 2009 00:49:07 GMT

I would like to use a Cisco VPN client with a Netgear FVS318 V3 ,,,,,I know how to configure Netgear FVS318 V3 for IPsec,,,because I am using TheGreenbow client now with it.

But I do not know how to configure Cisco VPN

I just want to find out how to do that ? specially with the option "Group Authentication" which it asks about username and password.

Thanks

Internet Connection not accessible.

Techieskull — Sun, 15 Nov 2009 02:05:53 GMT

I'm a new user of Ubuntu. I requested the Ubuntu 9.10 cd online and got it in around 3 weeks. I've chosen the 'Install over windows' option for my use right now. The version of windows being 'Windows 7'. The problem is that I'm unable to connect to the internet. I'm using LAN cord to connect to my modem. The 'Network Manager' tht the user manual talks about, is not to be found yet. When I click on the 'Network' icon on the top right portion of the panel, it shows that 'autoeth0' is connected but when I open firefox and try to open any website, the 'Server not found' comes up on the firefox window. Thus I'm not able to surf the web.
Please suggest me something to solve this.

fantaip shows "Fnta [Error fantaip.c:428] short packet!!!!"

yu_zyy — Fri, 13 Nov 2009 20:01:16 GMT

Hi,

I try to use unicornscan and fantaip on Ubuntu.

sudo fantaip -i eth1 192.168.0.200

The fantaip shows the following error when runs as

" Fnta [Error fantaip.c:428] short packet!!!!"

I googled, found a thread by Robert E. Lee and I tried his steps:
5) patch -p1 < ../attributemissing.patch
6) make install

but I still gets this problem.

Really appreciate anyone can help.

sudo iwconfig ra0 essid "xx" does not work

gwang09 — Thu, 12 Nov 2009 02:27:03 GMT

Hello Linux network friends,

I am currently having a problem in switching wireless network (ap) manually using the following command:

--$sudo iwconfig ra0 essid "network name"

Although there is no error in executing this command and the LED on the adapter blinks for a few times, the network (ap -- access point) hasn't change. My linux distribution is Ubuntu 8.10, linux 2.6.7-27-generic. The wireless adapter is WUSB600N USB stick (Ralink's RT2870 chipset). All the networks do not require key (encryption key: off). Please help.

Regards,

George

Netgear FVS318 V3 and TheGreenBow Client VPN

zillah — Wed, 11 Nov 2009 22:40:16 GMT

Hi

I tried to follow the instruction in the guide line below (Under Netgear FVS318 V3)

Certified VPN Gateways List - VPN Configuration tutorials and guides

It worked the first time then after that I do not know why stopped working!!!

This is my configuration for the router FVS 318 V3 and The Green bow client

Imageshack - ikepolicyfvs318

Imageshack - vpnpolicyfvs318

Imageshack - phase1

I could not figure out where is the problem ?

Thanks

Somewhat Newb needs SNMP help

joe1871 — Wed, 11 Nov 2009 19:59:14 GMT

I have an SNMPget statment that I am trying to plug into Nagios to monitor the CPU I/O Wait Time on several Debian /Xen Host servers. They are Net-SNMP compliant.

If i run the snmpget querie it returns the following:

UCD-SNMP-MIB::ssCpuRawWait.0 = Counter32: 484856

How do I interpret this data? What is Counter32? Is there a better way to build the snmpget querie that will output meaningful data? (I am sure the above is meaningful to something/somebody, but I don't have a clue...)

Thanks in advance

Joe

firefox tunnelling issue

lock5251 — Tue, 10 Nov 2009 15:33:41 GMT

This is an old post but its related so here goes.

Here is the scenario... and any suggestions on a different way to do this would be equally welcomed.

I've set up a linux box with hardy on it for users to use for accessing the bank website.

What I've done is used the ssh protocol to remote into the linux box to access the banking website remotely from their computer but through a secure channel on a secured box.

I used xming as the xwindows program on windows and firefox with ie addon on ubuntu to access the webpage via ssh.

The problem seems to be that firefox doesn't work when attempting to upload files from a network share (or locally from the linux box) to the webpage.

The 'open files' browser hangs or even doesn't show the folders when it comes up.

With the network shares I used the cifs protocol to map the windows shares to the profiles. And I don't know if this is of any relevance but I've added the linux box to the domain using likewise-open and thus it authenticates with the active directory.

I have not configured firefox to use the socks5 protocol because this would inconvenience the user. Instead I have written a script to streamline the ssh login and pull up firefox with a simple double click and entering of a network password which then brings up a firefox window that looks as if it were running natively on windows thanks to xming;)

An alternative solution I tried but did not pan out was to use ie4linux but that hangs up the whole system. I've also tried chromium, which actually runs superb and even browses great, but does not have internet explorer compatibility which is needed for our banking website.

Any suggestions would be greatly appreciated since I've posted elsewhere and have not received any assistance yet.

Socket Server breaks after 1000 client requests

probe — Mon, 09 Nov 2009 15:31:15 GMT

Hi,

I wrote C++ Socket class. This class wraps methods both for client and server,
so you can create server or client depending what methods you call.

Anyway, all in all, problem is:

I have 3 small programs. One is server that listens in loop on port 30000.
Second is client program that sends one message to the server.
The third one on is small program (called spawn) that forks and executes client program in limited for loop. So , idea is to simulate a lot of connections to the server and see how many he can handle and how.

So, at first I start server, execute spawn, and server gets client messages. First I try 10 clients, then 100, then 1000 and it worked :) Then I tried 10000 clients, and then it breaks just above 1000 clients, plus minus 100 !! So then I tried to put in server code 5 threads and mutex, but the result is same around 1000 clients and breaks. Then I put semaphore, but then i realized that in this scenario semaphores are of no use, because you can not sync with random client events.

I also tried to change value in listen() method, but then I read somewhere that maximum is 5 connections, which is default.

Does this problem requires some change in kernel code, or tcp/ip stack, or the solution is simple, like reset server when it has first break. I tried this last solution, but nothing happens.

So , does anyone have any idea?

Please help, I am working on this for days :)

thanks:eek:

smbpasswd

rakeshvijayan — Mon, 09 Nov 2009 09:43:51 GMT

hi friends
i wish to know for what we use -a after smbpasswd
like: smbpasswd -a username

thanks:eek:

How to make a linux machine as a proxy server.

maheshgupta024 — Mon, 09 Nov 2009 05:50:32 GMT

Hi.. I want to learn some stuff..
I have 3 systems in my home. Also I have an internet connection which I want to use for 3 systems.. I have a server where I installed linux in the machine. I want to set the linux server as a proxy for these 3 systems. How do I start this stuff..

Thanks in advance