Managing and using network connectivity on a unix system

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Questions about nmap

I have several questions about nmap. First, nmap can detect servers via: link-layer network-layer transport-layer What are the differences (not in the layer, but in the way that nmap does it) and ...
3
votes
1answer
680 views

Filter out HTTP GET request within wireshark?

I'm trying to filter out HTTP GET with wireshark, but the string provided on the official page isn't working at all: port 80 and tcp[((tcp[12:1] & 0xf0) >> 2):4] = 0x47455420 Wireshark on ...
4
votes
2answers
427 views

How can I use one network port for VPN and the other for everything else?

My Linux machine has two network ports with two IP addresses. I want to use one port for my VPN and accounting, and the other port for other usages. How can I tell Linux not to allow any requests from ...
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1answer
3k views

How to run tcptraceroute utility on UNIX machine?

How can I run the tcptraceroute utility on a UNIX machine? I want to run a TCP traceroute for port 80.
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0answers
357 views

Juniper SRX210, how to make DHCP to Static IP?

I am very new to Juniper device. I have a SRX210 router, and i am testing how to setup Static IP. So i did: set interfaces ge-0/0/0 unit 0 description ISP Link set interfaces ge-0/0/0 unit 0 family ...
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5answers
8k views

What is the need for rsync server in daemon mode

I don't understand the need for an rsync server in daemon mode. What are the benefits from it if I can use rsync with SSH or telnet?
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2answers
3k views

How to connect two computers via internet with ssh?

I want to connect another computer via internet that doesn't have a public IP. Is there any away to do this?
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0answers
196 views

configuration for my wireless connection

I had connection issues so I changed some wireless configuration. I think I solved the problem, but I still have minor issues. First thing I had my Internet connection freeze badly, Then after doing ...
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4answers
4k views

Can't Install/Update packages on newly installed CentOS

I installed CentOS6 and it is the first time. I tried to install/update packages. But I coudn't. Here is the output and it doesn't stop. How can I solve this? [root@localhost suranga]# yum update ...
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3answers
52k views

How can I know if IP Multicast is enabled

I have scripts that run IP multicast tests; however, my scripts are failing on a particular linux machine. I know that I can look at CONFIG_IP_MULTICAST in the kernel configuration file to determine ...
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0answers
730 views

tunneling FON traffic via Tor

I would like to tunnel the traffic of my FON router through Tor. For that I added a second network card to a local server and connected the FON router to it. Then I set up a DHCP server and configured ...
1
vote
1answer
440 views

NetworkManager on Fedora 15 can't find frequently used wireless network

NetworkManager has refused to find the wireless network I always connect to. It sees other wireless networks except the one which I need. In recent past occasions, I've had to delete the wireless ...
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4answers
3k views

How to set domain name in Crunchbang GNU/Linux?

How can I set the domain name in GNU/Linux?, I am using Crunchbang and I need to set the domain name for my LAN network. EDIT: Let me talk more about my problem: I need to configure a LAN network for ...
3
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1answer
494 views

Labeling/Aliasing multiple network addresses

If my machine is connected to several networks and configured with multiple addresses (ipv4), is it wise to configure and use labels to identify them ? By labels I mean the iproute2 ip command's ...
2
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1answer
3k views

iptrace for linux: how can I trace full packet contents?

I normally use iptrace on our AIX servers to get packet traces but have recently found out that this doesn't work for other 'nix systems - namely Centos. Does anyone know what the analog would be? ...
3
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2answers
4k views

No, I don't want persistent net rules

I have a bootable Linux memstick that I use on a lot of different PCs (but all of the same model and configuration). Trouble is that udev is renaming the eth interfaces so that what was eth0 on the ...
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2answers
2k views

What's the next step in troubleshooting this wireless connection failure?

I just installed Ubuntu 10.04.3 to dual-boot with Windows. I can connect to the Internet using a wired connection, but not through wireless. The first time I booted, the wireless notification bar ...
4
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1answer
6k views

CentOS doesn't know what the internet is

So I've done my share of investigating this problem... I just recently created a CentOS 6 VM on my LinuxMint box using VirtualBox. I left all the recommended values the same upon creation (8GB HDD, ...
4
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1answer
157 views

connect() blocked for 3 seconds after a lot of success connect()

I am writing a client-side application which connect() to a server and close it in a for loop. The connect() is done in blocking-mode, and I found that some connect() call will block for about 3 ...
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2answers
388 views

Is it possible assigning an separate LAN IP to service/daemon?

I'm using pfsense for prioritizing traffic around LAN. It works well for specified port, IP, network, but I'm having a problem with torrent (transmission bittorrent) outbound connections. The outbound ...
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2answers
489 views

UDP NAT Punching

I have the following two problems. Please help me to solve them: In symmetric NAT, as I know, the local hidden node (behind the NAT) must initiate connection in order to create a window in the NAT ...
3
votes
1answer
846 views

How can I update the OUI list used for Netdiscover?

Netdiscover keeps showing a lot of "Unknown vendor" devices, when I generally can find the vendor pretty quickly via Google. Is there any way to manually update whatever OUI list Netdiscover uses?
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0answers
699 views

Wireless rtl8187 freezes intermittently

I am using a wireless USB ALFA 036H. Linux Mint (32-bit) recognizes it without any drivers but it stops downloading/uploading and I have to reconnect to get it to work again. I tried to find a ...
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2answers
2k views

Checking the type of NAT

I have read that there are many types of NATs available like symmetric NAT, full-cone NAT, etc. If I am behind a NAT, is there any way to find out the type of NAT behind which I am currently working ...
2
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0answers
795 views

Mount Freecom Classic SL Network Drive (NDAS) in Ubuntu 11.10

Both the Network Drive and the Ubuntu machine are connected by Ethernet to a Linksys WRT54GL router (192.168.1.1). To access the Network Drive in Windows, I installed the NDAS software and mounted ...
2
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1answer
725 views

Is vnstat reporting accurate?

I'm checking the stats of a busy site that host mirror downloads. I installed vnstat on the machine and after a few days i saw the number 125.25 Mbit/s or using -ru 0 15.29 MiB/s I'm extremely ...
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2answers
2k views

Why does my USB wireless network adapter disconnect every few seconds?

I don't have experience with drivers and other things. After installing Linux Mint 11 on my machine (I did a dist-upgrade), everything seemed to be great -- I didn't need to install any drivers. After ...
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1answer
762 views

VirtualBox host-only network suddenly stopped working , no interface available inside

I'm unable to setup host-only network in virtualbox suddenly , please see my screenshot , there's no entry in "Name" comboBox
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2answers
527 views

Network file sharing with freebsd server

I have a freebsd server at home. I also have other OSes like linux and windows connected to the same network via WLAN (wifi). I want to be able to share stuff (what ever I download ;)) on my FreeBSD ...
2
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1answer
1k views

Atheros ar8151 driver for kernel 3.x (fedora 16)

Yesterday, I installed Fedora 16 and found no wireless connection available. Then I found the ar81family driver But it seems like it does not work with kernel 3. I changed the makefile to ignore ...
3
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1answer
218 views

Doing nmap on a network

I used nmap to scan all the ports in the hosts in a network by using the command: $ nmap 172.31.100.0/24 What I found is that it showed the following in the result: Nmap scan report for ...
6
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2answers
686 views

How can I test the current carrier state for an ethernet adapter in Linux?

In Arch Linux, how can I check if a network device (say eth0) has a carrier signal present?
4
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3answers
5k views

How I can know the IP address of other users logged at the same remote machine?

I can see the names of other users on the remote machine with the who command... I'd also like know the IP address of those users... I was trying with the commands /sbin/ifconfing and netstat but I ...
2
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0answers
584 views

Enabling multicast communication between 2 AIX JVM processes

I'm having trouble with multicast distribution on a single AIX machine between two JVM processes. Think ehcache or jgroups. In order to enable on Mac OS X: route add -net 224.0.0.0 -interface lo0 ...
7
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1answer
8k views

Why are incoming packets on a TAP interface seen with tcpdump but not with iptables?

A program injects packets on a Linux TAP interface (these packets are coming from a virtual machine). Specifically, these are DHCP requests (so they're UDP). I can see the packets with tcpdump but not ...
3
votes
1answer
233 views

Detecting multihomed machine

Is there a way to reliably detect whether or not a machine is multi-homed? I'd like to be able to write a script that will return a true or false regarding that information.
4
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2answers
929 views

How to configure Linux to use DHCP or static IP depending on presence/absence of DHCP server?

I would like to configure a network interface to make use of DHCP if a DHCP server is present on the network during boot, but otherwise default to some default static IP address.
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2answers
11k views

Oracle Linux 6.1 guest on Virtualbox 4.1 can't connect to network

I just installed VirtualBox 4.1 on my Windows system, and then added a Solaris 11 Express guest and an Oracle Linux 6.1 guest. Both installs went smoothly. But while the Solaris 11 guest has network ...
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vote
1answer
493 views

How to configure a Frame Relay in Unix/Linux?

I am in a Networking course, the course employs a Cisco packet tracer to practice before the real implementation, but I only use GNU/Linux (Debian Squeeze) and I need to configure a next network ...
0
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1answer
676 views

How to enable TCP connection in Debian Squeeze?

I need enable TCP connections to my system, for use graphical applications in marionnet, network simulation system, in debian squeeze. In older versions of debian it is achieved with ...
3
votes
3answers
2k views

Arch Linux doesn't connect to a wireless network

I'm using Arch Linux on a Thinkpad machine. Everything was satisfactory but today I restarted my router and the machine doesn't connect. The router is fine (another machine and a cell phone connect to ...
2
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1answer
69 views

How do I proceed further when my reports of a improper functioning of a gnome component has not met with answers on the respective mailing list

I am unable to connect to internet using my modem. I followed instructions to seek help at http://live.gnome.org/NetworkManager/Debugging and posted on ...
3
votes
1answer
546 views

KVM: network partially lost for the host, guests are fine

I got KVM working fine on a Linux system, for quite some weeks. Then today something weird happened: suddenly the host (and the host only) lost some of its Internet access: it can still access the ...
6
votes
3answers
11k views

Wireless networking with CentOS

I'm running CentOS 5.7 x86 on my Vostro 1700 laptop which has an Intel Pro Wireless WiFi NIC (Intel Pro Wireless 3945 [iwl3945]). I'm a bit confused about how my Wireless connection (wlan0) is being ...
10
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1answer
3k views

what level of the network stack does tcpdump get its info from?

As I was trying in vain to fix a faulty ethernet controller here, one thing I tried was running tcpdump on the machine. I found it interesting that tcpdump was able to detect that some of the ICMP ...
2
votes
1answer
147 views

Start and stop multiple executable for easy debugging

I'm debugging a networking project, which involves interacting of 3 programs, ie a server, two different clients. However I find it difficult to start and stop them for debugging. Some methods I have ...
1
vote
1answer
11k views

Mount a Windows network drive

I want to mount a netword drive on the server (SBS2008). I have two options: Either using a fedora which already mounts on a CentOS server or directly on the CentOS server. Here is the command I tried ...
2
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1answer
3k views

Where are Proxy Settings Stored?

I'm coding a small application that connects to the Internet and retrieves information from my server using bsd socket. I looked at where the proxy settings are stored under Linux but i couldn't the ...
3
votes
2answers
3k views

OpenVPN bridge. Can't access machines on local network

Followed this guide: https://wiki.archlinux.org/index.php/OpenVPN_Bridge This is my setup: I have a wireless router(192.168.2.1) which connects to the Internet through a PPPoE connection and acts as ...
4
votes
1answer
2k views

Debian 6.0 system with 2.6.39 kernel dropping packets, sandy bridge hardware

I recently migrated an existing Debian system to new hardware, a core i3 chip running on an intel sandy bridge motherboard. I’m experiencing a very strange problem; when I ping my router, about 50% of ...