Managing and using network connectivity on a unix system

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4
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3answers
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IPTables and transparent proxies

I have set up a local, transparent TCP proxy on localhost. I want to redirect ALL TCP traffic to this proxy, so it can handle it and nothing "leaks out," circumventing the proxy. I need to use ...
2
votes
1answer
207 views

Testing intranet network

This is probably a question already discussed here and there. I'd like to try to gathering here all the information. Suppose I'm on a machine connected to a network. This network has access to the ...
3
votes
3answers
3k views

How do I deploy Firefox Bookmarks for all users in the network?

I have a bash-script for installing Firefox which is downloaded and executed from every client workstation in the network. The script is on the server and all workstations are running Ubuntu. Now I ...
12
votes
3answers
27k views

Output traffic on different interfaces based on destination port

My question is basically the same as Only allow certain outbound traffic on certain interfaces. I have two interfaces eth1 (10.0.0.2) and wlan0 (192.168.0.2). My default route is for eth1. Let's say ...
3
votes
5answers
1k views

How can I test whether connection to the given host/port is established in Bash?

Currently I'm using netstat for this: if netstat -an | grep ESTABLISHED | grep $address:$port > /dev/null; then # command fi Is there a more elegant solution?
23
votes
4answers
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How to speed up X over SSH on a slow network connection?

Are there any specific recommendations on speeding up X applications over ssh on a slow network connection? In this specific case, I am accessing a server located in west coast from a laptop in east ...
0
votes
1answer
483 views

Private vlan concept (rfc 5517)

I'm learing vlan concept and came around private vlan rfc. I think that i understand the reason and implication of isolated domain, but i'm not sure that i understand the community domain. ...
3
votes
3answers
6k views

How should I determine the current network utilization?

I want to display the current network utilization (bandwidth usage) of one interface of a Debian box on a website. It is not supposed to be very elaborate or precise, just a simple number such as "52 ...
14
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3answers
13k views

Does mount always require root privileges?

I was under the impression that any sort of call to mount requires root privileges. But recently I was told "You should instead create appropriate entries in /etc/fstab so that the filesystems can be ...
4
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1answer
3k views

How do I recover/kill an SSH session after losing connection?

I lost my connection while I was logged via SSH into my university server. Classic. Now I can't log in since the session appears to be still running and I get the error "Too many logins for ...
0
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2answers
1k views

Dropbox doesn't connect properly on boot

I'm having a problem with Dropbox (version 1.1.35). When I first boot it takes some time before Network Manager connects to the WLAN. Then I see the Dropbox icon in the task list, claiming to be ...
1
vote
1answer
1k views

New SL6 system: No hostname?

This is in regards to Scientific Linux 6.1 system, but should also apply to CentOS 6.1 & RHEL 6.1. I am setting up a new Scientific Linux 6.1 system, using kickstart and DHCP (via xCAT). This ...
1
vote
1answer
2k views

What does this error mean: “igmp[1435]: setsockopt IP_MSFILTER”?

My network connection is pretty crappy today so I looked at my router (TP-LINK TD-W8950ND) logs and can see these entries a few times every minute: Date/Time Facility Severity Message Sep 7 ...
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votes
4answers
2k views

How can I send spoofed packets in Linux

In order to test a firewall, I want to send malformed packets to its interface, regardless of my routing table. Is there a way to ask linux "send this exact tcp package, to this MAC address, ...
2
votes
2answers
349 views

UDP multicasting broken after kernel update

I've got an embedded system which is running a stripped down Gentoo userland with a manually build kernel. The system acquires data from a PCI card and sends it out to an UDP multicast group. All ...
2
votes
0answers
474 views

Why are packets not moving forward? [closed]

I have a server with forwarding turned on. I placed an iptables LOG target in the PREROUTING, INPUT, and FORWARD chains of the mangle table. I can see the LOG messages from PREROUTING, but not INPUT ...
2
votes
1answer
124 views

Reporting Network and Vital Statistics and writing to db and image

I am looking for a versatile tool that can write either to a MySQL db, or possibly simply even just write some image charts (that i can display on a PHP dashboard) to monitor my network health. Is ...
-1
votes
4answers
933 views

How can I configure IP address from class E on Linux?

I would like to configure an IP address from class E, for example 241.0.0.2. Currently Linux (Linux-2.6.21.7-hrt1) returns the following answer: ifconfig: SIOCSIFADDR: Invalid argument Is there a ...
4
votes
1answer
304 views

Reverse ip lookup

I was wondering if it is somehow possible to lookup the ip of a machine I ssh'd into from. This is the scenario, I'm at home, I've VPN'd into a server that I ssh into constantly in the office but now ...
1
vote
1answer
176 views

How to “set” this home network mesh up

I don't know much about networking security other than keeping unused ports closed is good. This is what I'm trying to accomplish: I need to be able to keep my server (the dotted line) with limited ...
4
votes
3answers
832 views

Access point (with hostapd) on the same interface as the network/gateway?

I wonder if it should be possible to have an wireless access point using hostapd (as described in Set up an access point) on the same interface that connects to a wireless network for internet. I ...
12
votes
5answers
9k views

How to recover a shell after a disconnection

Am doing some work on a remote centos 5.6 machine and my network keeps dropping. Is there a way i can recover my hung sessions after i reconnect? EDIT: am doing some updating and installing with yum ...
4
votes
1answer
963 views

Can I spoof the MAC address in Android?

Is it possible to spoof the MAC address of the wireless interface using wpa_supplicant.conf in Android when I connect as a client to an access point? Edit Unfortunately, Android doesn't support ...
2
votes
1answer
3k views

Why does iptables still block my samba?

I'm currently fighting with iptables and samba. I read that samba needs ports 137-139 and 445 open on both tcp and udp. Here is the relevant part of my iptables config ... # forward valid incoming ...
2
votes
1answer
3k views

Static routes in HP-UX

I need to set static route in HP-UX. I edited /etc/rc.config.d/netconf file and added new entry for my route: ROUTE_DESTINATION[1]="10.105.2.0" ROUTE_MASK[1]="255.255.255.0" ...
3
votes
2answers
149 views

How can I print out information about a Wireless Access Point in range?

How can I print out information about a Wireless Access Point in range? Can I for example get the MAC address?
6
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1answer
3k views

LXC container network/routing issues

I have been experimenting with LXC virtualisation in order to run virtual machines on a dedicated server, but am having trouble setting up the networking properly. I am using veth bridged networking, ...
2
votes
1answer
725 views

Is it possible to use Internet Connection Sharing with DHCP?

I know it is possible to share an internet connection with another pc using ip-forwarding and masquerade. Is it possible to set up the sharing computer as a DHCP server, so the settings (ip, gateway, ...
12
votes
1answer
8k views

Buffer size for capturing packets in kernel space?

Going through the man page of tcpdump, it seems kernel can drop the packets if the buffer is full. I was wondering if: that size is configurable and/or where can I see the size for my distro? From ...
3
votes
2answers
1k views

Which user group can use the 'tap' net device?

I use the 'tap' net device with KVM to get my vm connect to the Internet. But I have to be root, or use 'sudo', which is inconvenient. I think I can put my user account into some group so I can access ...
3
votes
1answer
2k views

Is it possible to capture all network traffic using tcpdump?

I have 3 computers on the same sub-net. Computer A and B are communicating with each other (ping, telnet, etc.). I'd like to see the packets between A and B on computer C. Is it possible to do this ...
1
vote
1answer
445 views

netcat throughput low but iperf high [closed]

I was testing the throughput between two pcs connected on the same router: one with 100mbps lan, the other with 54mbps wifi. I tested both netcat and iperf and the throughtput I get is only 2.6mb/s. ...
3
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1answer
1k views

Mounting a network drive automatically when needed and unmount it again after some time with inactivity

I have a somewhat old NAS hosting my music collection. It is not capable of running a DAAP media server so I have mounted the music folder on my Sheevaplug (a tiny headless server running Debian) ...
0
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1answer
1k views

How to configure DUAL-WAN on a Linux/*BSD machine?

I have two internet connections. The cables from the two ISP's (dhcp; 1-10/10 Mbit; 2-20/20Mbit connection) are on two interfaces: eth0 and eth1. On eth3 there is a Gbit switch and on the switch there ...
0
votes
1answer
471 views

Netdiscover packages for Fedora?

Ubuntu has a program called netdiscover. Netdiscover is an active/passive address reconnaissance tool, mainly developed for those wireless networks without dhcp server, when you are wardriving. It ...
7
votes
3answers
28k views

CentOS on HyperV - eth0 not in ifconfig?

I've launched a CentOS install in HyperV and assigned a NIC the same way I've done on an Ubuntu VM, however, the device simply isn't picked up. Only my loopback is found by ifconfig. How should I go ...
1
vote
1answer
342 views

Multicast on local box

I have an application I need to interface with that listens to a multicast address. I'd like to be able to run a program I've written and have it interface with the other application by multicast ...
1
vote
2answers
3k views

Check the Existence of a Network Interface Card Redhat

I'm aware that I can use ethtool eth0|eth1|eth2 to check the existence of a NIC. But I wonder where the files are on the machine that contain information of an existing interface, as I need to use ...
5
votes
1answer
3k views

Changing Redhat Network Settings From DHCP to STATIC IP Via Configuration Files

In order to make the statically assigned IP work, I have already modified the file /etc/sysconfig/network-scripts/ifcfg-eth0 as follows: DEVICE=eth0 IPADDR=10.33.17.143 NETMASK=255.255.255.0 ...
2
votes
4answers
959 views

Is there a way to determine machine hostname without touching “/etc/hosts”?

Considering that I'm in a LAN that assigns IP addresses using DHCP (and that I'm not its administrator), how do I set things up such that when I ping <hostname> (instead of ping <IP ...
34
votes
3answers
60k views

How to make a machine accessible from the LAN using its hostname

Here are details of the machine I want to access using its hostname: $ hostname hostname $ cat /etc/hosts 127.0.0.1 localhost 127.0.1.1 hostname.company.local hostname It's a default Debian 6 ...
2
votes
2answers
2k views

iscsi target to a folder of a mounted parition?

i'm thinking about installing and setting up iscsitarget on my Debian squeeze box. so far, the examples i saw on various Google searches and the debian wiki: ...
7
votes
1answer
4k views

Why is VirtualBox Bridged networking slow

When logged into the guest, data transfer (scp) from the host is very slow (<1MB/s). Is this expected? setup: VirtualBox host is Debian Unstable VirtualBox guest is Debian 6 (Squeeze) Bridged ...
1
vote
1answer
703 views

Only allow ssh/vpn on OpenWRT

If I don't want to use wireless encryption, but I still want security and I want to use sshuttle (on the clients, see: https://github.com/apenwarr/sshuttle/) for tunneling everything through an SSH ...
5
votes
4answers
2k views

How to share the internet connection?

An ordinally network topology in picture: In words: - "server" (e.g.: an Ubuntu 10.04 LTS) is connected to the "internet" through pppoe connection - "server" is using it's wireless card in AP ...
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vote
1answer
2k views

Redhat Network Service Restart

I modified the /etc/sysconfig/network-scripts/ifcfg-eth0 file to set a static ip for my redhat. Then I tried to use command "service network restart" to make the change stick, however, it became stuck ...
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4answers
4k views

ssh hanging then time out

I am new to ssh on linux. I have two computers connected on a switch. The first one is 192.168.1.2 and the second is 192.168.1.3. When I use the ping command I got a reply and everything is good, but ...
24
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1answer
13k views

Why are the first 1024 ports restricted to the root user only?

This is more idle curiosity than anything else. A friend of mine asked me 'which port range is it that only root can use under Linux?' I told him 0-1024 were restricted. Then he asked my why it was so ...
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2answers
10k views

How to refuse routes that are PUSHed by OpenVPN server?

When I establish an OpenVPN client connection over the Internet to our corporate OpenVPN server, it pushes several static routes. Unfortunately, these routes break some connectivity within my local ...
4
votes
1answer
2k views

How to set a static IP in Ubuntu

How do I set my computer to have a static IP in Ubuntu 11.04? The only two lines in /etc/network/interfaces are: auto lo iface lo inet loopback I think usually when people do this they have a wired ...