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  • DHCPD (Slackware) - Disabling auto-generation of gateway as DNS server

    - by Dogbert
    Good day, I am using a Linux workstation on Slackware 13.37. One "problem" I have had to deal with ever since 11.0 is the following: DNS servers are queried and determined at startup by DHCP daemon (DHCPD) This is invoked at startup by a script located at /etc/rc.d/rc.dhcpd My DNS servers for my ISP are resolved correctly, and are stored in a list located at /etc/resolv.conf However, the one annoying problem is that my gateway IP (ie: 192.168.1.1) is always automatically put at the top of the list in resolv.conf, meaning I have to always wait for a timeout before a valid DNS server is used to resolve an address (ie: timeout on 192.168.1.1 because it is not actually a DNS server, then DHCP uses the next server in the list). I could lower my DNS resolution timeout so the gateway query times out quicker, but that's not what I want, as I don't want to degrade the abilities of legitimate DNS servers. What I would like to do is change how DHCPD operates so that it does NOT put my gateway IP address at the beginning of this list. I've searched via "man dhcpd", etc, and haven't found the exact answer yet. Any help on this issue is appreciated. Thank you all in advance for your time and assistance.

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  • linux router setup

    - by nuttsduh
    Hi All, I a trying to setup a a linux router for the first time and i am struggling with the setup. Here how i want to setup it up: ISP line - Linux router - Linksys router - Lan. Linux router has eth0 and eth1 How do i setup this and where do i put my external ip? Many thanks,

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  • Ping with explicit next-hop selection (aka Monitoring multiple default gateways)

    - by Michuelnik
    I have a linux (debian) router with two internet connections (A) and (B). (A) is preferred, (B) is fallback. I want to monitor the internet connection (and not only the availability of the gateways!) and change the default route appropriately. If (A) is not providing internet, switch to (B) If (A) is providing internet again, switch back to (A). Only problem I have is in case (2). My routing table points towards a working internet so I cannot easily detect whether internet is working over link (A) again. I am search for a ping or traceroute (or other diagnosis-tool) which can select the next-hop explicitly. ping -r looks promising, but can only ping a host on the lan. (It only has to write another destination address in the packet, damnit!) traceroute -g gateway looks even more promising and nearly does what I want - but sets source routing options which my next-hops deny. (Not within my administrative boundary...) I just want a $ping, that can: select a source interface (and address) select a next-hop on that interface ping any arbitrary ip address I could do evil trickery with policy-based routing but that would have production impact for all users. I would like to see a side-effect-free solution....

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  • Raspberry pi slows down my entire network

    - by gnusouth
    Whenever my Raspberry Pi is connected to the network (via ethernet) the entire network is slowed to a crawl. On my main computer, ping times for google.com go from ~10ms to ~200ms and it takes forever to load web pages. Connections are also slow on the Pi, with an apt-get update showing pathetic speeds in the order of 1KB/s. Turning off the Pi completely removes the drag from the network. I've tried static and dynamic IP addresses for the Pi, but both have the same problems. I'm currently using Raspbian (downloaded today), but also had this problem with Arch Linux. I've checked the connection's duplex with dmesg | grep -i duplex, which shows that the Pi's connection is running at 100Mbps, full-duplex, as expected. My modem/router is a Billion 7404VNPX (an Australian thing); relatively high-end, albeit a bit buggy at times (it will occassionally delete all its firewall settings). It assigns IPs in the range 192.168.1.1 to 192.168.1.20 and has 192.168.1.254 as its own IP. When I assign static IPs I tend to use the 192.168.1.200 area. Does anyone have any idea as to what could be causing this weird slowdown? Or any tests I could try? Thanks

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  • Monitoring instantaneous network throughput at one second intervals?

    - by Shaddi
    For a testing setup I have, I need to monitor the throughput through a "router"* at regular intervals of around 5 seconds or less (sub-second intervals would be very nice, but not required). Ideally, I would be able to generate a file which contained both the number of bytes and packets seen during each interval. I will eventually be generating a time-series of throughput from this data. On a previous setup using an older version of FreeBSD, there was a tool called "bpfmon" which gave me this information. However, I need to do this under a modern version of Linux (namely, Ubuntu 11.04). I have looked at both iptraf and iftop, but these do not appear to provide the resolution I need, nor do they seem to easily allow scraping the data I need. I understand iptables statistics may be able to give me what I'm after, but the examples I've seen of this seem to rely on repeatedly reading and resetting traffic counters, which seems like it could give inaccurate as read/reset is not an atomic operation. I already capture a tcpdump trace of the traffic I'm interested in on the link I want to monitor, so I am open to approaches which simply parse that. I feel like this must be a common problem though, so I am hoping there will be a standard "best practice" tool for accomplishing this. *I say "router" in quotes because I am really talking about a machine with two bridged NICs through which all the traffic I'm interested in passes.

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  • PPTP: Linux clients unreachable

    - by Bahman
    I have setup a PPTP server on a CentOS 6 box. Several clients (Windows and Linux) connect to this server. All clients use the same subnet. All clients (Win or Lin) can surf the Internet using the VPN successfully. Windows clients can ping any other Windows client (XP/Vista/7) connected to VPN. Linux clients (KVPNC) can ping any Windows client (XP/Vista/7) connected to VPN. So far so good. But there's this weird problem and I've been trying to figure it out with no luck: No client can ping (reach) a Linux client (successfully) connected to VPN. And yes, the firewall is completely disabled. I'd really appreciate any hint/idea. TIA, EDIT: The ultimate goal of this is to share services across the VPN, like accessing a HTTPD running on a Linux box from a Windows client.

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  • Preventing endless forwarding with two routers

    - by jarmund
    The network in quesiton looks basically like this: /----Inet1 / H1---[111.0/24]---GW1---[99.0/24] \----GW2-----Inet2 Device explaination H1: Host with IP 192.168.111.47 GW1: Linux box with IPs 192.168.111.1 and 192.168.99.2, as well as its own route to the internet. GW2: Generic wireless router with IP 192.168.99.1 and its own route to the internet. Inet1 & Inet2: Two possible routes to the internet In short: H has more than one possible route to the internet. H is supposed to only access the internet via GW2 when that link is up, so GW1 has some policy based routing special just for H1: ip rule add from 192.168.111.47 table 991 ip route add default via 192.168.99.1 table 991 While this works as long as GW2 has a direct link to the internet, the problem occurs when that link is down. What then happens is that GW2 forwards the packet back to GW1, which again forwards back to GW2, creating an endless loop of TCP-pingpong. The preferred result would be that the packet was just dropped. Is there something that can be done with iptables on GW1 to prevent this? Basically, an iptables-friendly version of "If packet comes from GW2, but originated from H1, drop it" Note1: It is preferable not to change anything on GW2. Note2: H1 needs to be able to talk to both GW1 and GW2, and vice versa, but only GW2 should lead to the internet TLDR; H1 should only be allowed internet access via GW2, but still needs to be able to talk to both GW1 and GW2. EDIT: The interfaces for GW1 are br0.105 for the '99' network, and br0.111 for the '111' network. The sollution may or may not be obnoxiously simple, but i have not been able to produce the proper iptables syntax myself, so help would be most appreciated. PS: This is a follow-up question from this question

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  • Bypass network stack. Which options do we have? Pros and cons of each option [on hold]

    - by javapowered
    I'm writing trading application. I want to bypass network stack in Linux but I don't know how this can be done. I'm looking for complete list of options with pros and cons of each of them. The only option I know - is to buy solarflare network card which supports OpenOnLoad. What other options should I consider and what is pros and cons of each of them? Well the question is pretty simple - what is the best way to bypass network stack? upd: OpenOnload It achieves performance improvements in part by performing network processing at user-level, bypassing the OS kernel entirely on the data path. Intel DDIO to allow Intel® Ethernet Controllers and adapters to talk directly with the processor cache of the Intel® Xeon® processor E5. What's key difference between these techologies? Do they do roughly the same things? I much better like Intel DDIO because it's much easy to use, but OpenOnload required a lot of installation and tuning. If good OpenOnload application is much faster than good Intel DDIO application?

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  • how to make solaris more friendly for a linux user

    - by user10015
    Hi there, I've been a linux user for years. Very used to the bash shell, used to linux shell key mappings that come with most mainstream distros. I'm also a happy vim user in linux & love my arrow keys. Just started a job where 90% of the systems are solaris & the default shell for administrators is ksh. The key mappings, things like autocomplete & history not working they way they should and is driving me insane. I've been told that i can change solaris bash, but it still doesn't feel like linux. How do I make things run they way I'm used to? Can someone please put me in the right direction.

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  • Mac/Linux Dual Boot

    - by user38008
    I trying to create a dual boot of linux and mac without bootcamp. But I'm nervous that I'll screw up or lose my data. In disk utilitys I made a 45gig partion called linux but I dont know how to format it and if it matters at all.... Also, when the partition is done. I press cntrl when booting up select that Linux partition and put in the livebootUSB or CD right?

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  • Siege - running a stress test benchmark

    - by morgoth84
    I need to do a benchmark test of a HTTPS server using Siege, to see how it behaves under massive load. I'm initiating tests from another machine which is quite powerful and it is connected to the same physical switch the server is connected on. But when I initiate a test, I can't get it to make more than 170 requests per second. With this load the server's CPU usage is at 15-20% and the average response time for a request is approx. 0.03 seconds. Load of the client machine is approx. at 10%. So, I gradually increase the number of users in Siege (the number of worker threads) and request rate linearly increases up to 170 reqs/sec, but it never gets over it. No matter how many more worker threads I start, the load on the server is never more than 20% (and the client's load also doesn't increase any more). How can I overcome this? I've googled a bit and found out that after a request is completed, a socket associated with one ephermal port remains in WAIT_TIME state for some time during which it can't be reused. I tried to overcome this by doing these things: sysctl -w net.ipv4.ip_local_port_range="1024 65535" echo 1 > /proc/sys/net/ipv4/tcp_tw_recycle Oh, and the client machine is a Linux (RedHat, I think, but I'm not sure). Any help would be appreciated.

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  • Linux browse and open network files with command line

    - by user3077066
    I'm new to Linux. I have a Windows network connected to a Linux computer. When I try to browse Windows files from windows managers in Linux, it asks for user name, work group name and password. The address of computer network is something like this: smb://computer-name/folder I want to access my network folders and files using command line. I have searched a little bit but I didn't find anything. Any suggestions? Thanks in advance

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  • Connect Linux machine to a windows active directory

    - by ssl
    Hi, I have a Linux machine which connected to an Active Directory on Windows server. I configured the NIC to get an IP from the DHCP (from the windows server) however, when I try to get nslookup on the Linux side it doesn't work (connection timeout), but on the same machine when I load windows and do nslookup it works. what can be wrong with my Linux configuration or Windows DNS configuration? note: I've configured my DNS to nonsecure and secure connections. 10x!

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  • SSH from Windows to Linux without entering a password

    - by Josh
    I am trying to use ssh/scp from Windows to Linux without having to enter a password. This is what I have done, and it doesn't seem to work: generated public and private keys using Putty Key Generator (on Windows) saved the files as id_rsa.pub and id_rsa copied them into ~/.ssh added id_rsa.pub to the Linux box in ~/.ssh/authorized_keys I then try to ssh to the Linux box from Windows and I still have to enter a password Am I missing something?

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  • Archlinux/atheros WLAN configuration troubles

    - by GrinReaper
    I'm trying to config archlinux to use my wireless network adapter. It's quite troublesome. From what I've gathered, it's an atheros network adapter, using the ath5k driver/module... I can't get it to work; any ideas? Here's some of the output from my tinkering: # lspci | grep -i net 00:0a.0 Ethernet controller: nVidia corporation MCP67 Ethernet (reva2) 03:00.0 Ethernet controller: atheros communications inc. AR5001 Wireless Network Adapter (rev01) # lsusb ... Bus 004 Device 003: ID 03f0:17d Hewlett Packard Wireless (Bluetooth + WLAN Interface [Integrated Module] # ping -c 3 www.google.com ping: unknown host www.google.com #ping -c 3 8.8.8.8 ping: network is unreachable # lspci -v 03:00.0 Ethernet controller: atheros communications inc. AR5001 Wireless Network Adapter (rev01) ... Kernel driver in use: ath5k Kernel modules: ath5k # dmesg |grep ath5k registered as phy0 registered led device ath5k: atheros chip found PCI INT A disabled registered led device registered as phy1 # ip addr | sed '/^[0-9]/!d;s/: <.*$//' 1: lo 2: eth1 3: eth0 # ip link set <interface> up/down RNETLINK answers: Operation not possible due to RF-kill Also, is there a way to dump text from command-line to a text file so i can just copy pasta? Sorry, first time using a linux distro... EDIT: So I just tried this: I actually just did this twice. (I can't tell which setting is on/off for my wireless adapter. The lights are blue all the time now.) #rfkill list 0: hp-wifi: wireless lan softblocked: no hardblocked :yes 1: hp-bluetooth: bluetooth softblocked: no hardblocked :yes 3: phy1: wireless lan softblocked: no hardblocked :yes #rfkill list 0: hp-wifi: wireless lan softblocked: no hardblocked :no 1: hp-bluetooth: bluetooth softblocked: no hardblocked no 3: phy1: wireless lan softblocked: no hardblocked :yes 7: hci0: bluetooh 0: hp-wifi: wireless lan softblocked: no hardblocked :no I've dug around some other articles and it seems like ath5k is supposed to be preferable to madwifi, so should i be using madwifi? I'm 99% sure I disabled the hardblock (by turning it ON) but, as shown above, phy1 wireless lan is STILL hardblocked. What gives? Maybe I've made some more fundamental error in a basic config file? EDIT: I've fixed the hardblock. I've tried pinging www.google.com, but to no avail. I get: ping: unknown host www.google.com In the arch wiki: Edit /etc/hosts and add the same HOSTNAME you entered in /etc/rc.conf: 127.0.0.1 archlinux.domain.org localhost.localdomain localhost archlinux To my understanding, hostname is just a user-specified and based on preference(?) My /etc/rc.conf: HOSTNAME="gestalt" My /etc/hosts: 127.0.0.1 localhost.localdomain localhost gestalt but should it be the following? 120.0.0.1 localhost.domain.org localhost.localdomain localhost gestalt

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  • Wirelss card not being detected in backtrack 5

    - by Jesse Nelson
    I just installed backtrack 5 and I am unable to detect my wireless card. iwconfig doesn't list my interface. I can see that the hardware is present in lspci -vnn (see below) but I can't get the interface detected. I have tried to reinstall the compat-wireless package but I get errors during the build (see below) I have done a ton of researching and I keep hitting a brick wall, mostly because the wiki for backtrack is down and I can't find any good resources. Does anyone know how to fix the issue? Also, does anyone no how I can scan the hardware to determine what NIC is assigning my interface? If I can figure out the interface name I think I can set it up manually by putting up the link and using wireless-tools to manually configure the connection, this is what I had to do in arch on my mac. As stated the wiki for backtrack is down and I can't find any help on the issue. I tried to do the full kernel upgrade suggested in my software update but after the update was complete and I logged back in I had a new log in manager and the only thing I was able to log into was window managers. However, after this update my wireless was working fine. Please help I am new to Linux and the wiki is down, I have nowhere else to turn. Forgot to mention I am using the KDE version, not Gnome. Thanks in advance for any help or support. Attempt at make: root@bt:/usr/src/compat-wireless-3.3-rc1-2# make /usr/src/compat-wireless-3.3-rc1-2/config.mk:254: "WARNING: CONFIG_CFG80211_WEXT will be deactivated or not working because kernel was compiled with CONFIG_WIRELESS_EXT=n. Tools using wext interface like iwconfig will not work. To activate it build your kernel e.g. with CONFIG_LIBIPW=m." make -C /lib/modules/2.6.38/build M=/usr/src/compat-wireless-3.3-rc1-2 modules make: *** /lib/modules/2.6.38/build: No such file or directory. Stop. make: *** [modules] Error 2 lspci output: root@bt:/usr/src/compat-wireless-3.3-rc1-2# lspci -vnn -i net lspci: I/O error at net, line 0 root@bt:/usr/src/compat-wireless-3.3-rc1-2# lspci -vnn 02:00.0 Network controller [0280]: Atheros Communications Inc. Device [168c:0032] (rev ff) (prog-if ff) !!! Unknown header type 7f ( This is the problem but I can't find the solution) Kernel modules: ath9k iwconfig output: root@bt:/usr/src/compat-wireless-3.3-rc1-2# iwconfig lo no wireless extensions. eth0 no wireless extensions.

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  • Want to Patch your Red Hat Linux Kernel Without Rebooting?

    - by Lenz Grimmer
    Patched Tube by Morten Liebach (CC BY 2.0) Are you running Red Hat Enterprise Linux? Take back your weekend and say goodbye to lengthy maintenance windows for kernel updates! With Ksplice, you can install kernel updates while the system is running. Stay secure and compliant without the hassle. To give you a taste of one of the many features that are included in Oracle Linux Premier Support, we now offer a free 30-day Ksplice trial for RHEL systems. Give it a try and bring your Linux kernel up to date without rebooting (not even once to install it)! For more information on this exciting technology, read Wim's OTN article on using Oracle Ksplice to update Oracle Linux systems without rebooting. Watch Waseem Daher (one of the Ksplice founders) telling you more about Ksplice zero downtime updates in this screencast "Zero Downtime OS Updates with Ksplice" - Lenz

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  • Do I need to have antivirus software installed on a Linux distro?

    - by Vinaychalluru
    I thought that there was no need to scan for viruses in Ubuntu or any Linux distros until I found a virus scanner package named 'clamtk' and 'klamav' in Ubuntu software center yesterday. This leads to the following questions: How do viruses differ between Linux and Windows? How do the strategies for protection differ between Linux and Windows? Should a virus scanner package be installed on my system? If so, which would be a better option?

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  • Cannot ping host stale ARP cache?

    - by gkchicago
    I am having a strange issue with a Debian (Lenny/Linux 2.6.26-2-amd64) that has been driving me nuts. On some machines within my network I can ping the host in question just fine, other times I have to manually hard-code the ARP ethernet address for the IP in order to establish connectivity. I've finally worked it down to somehow involving ARP. I just found how to fix it in a way that made it work but I'm looking for help explaining this issue and also I don't trust my fix to be permanent.. My thought process has been the following but I just can't make any sense out of it: Could it be the card? (Intel 82555 rev 4) Could it be because there are two network cards? (Default route is eth0) Could it be because of the network aliases? Lenny? AMD x86_64? Argh.. Thank you for any insight you might have // Ping doesn't go thru [gordon@ubuntu ~]$ ping 192.168.135.101 PING 192.168.135.101 (192.168.135.101) 56(84) bytes of data. --- 192.168.135.101 ping statistics --- 4 packets transmitted, 0 received, 100% packet loss, time 3014ms // Here's the ARP Table, sometimes the .151 address is good, sometimes it // also matches the Gateways MAC like .101 is doing right here. [gordon@ubuntu ~]$ cat /proc/net/arp IP address HW type Flags HW address Mask Device 192.168.135.15 0x1 0x2 00:0B:DB:2B:24:89 * eth0 192.168.135.151 0x1 0x2 00:0B:6A:3A:30:A6 * eth0 192.168.135.1 0x1 0x2 00:1A:A2:2D:2A:04 * eth0 192.168.135.101 0x1 0x2 00:1A:A2:2D:2A:04 * eth0 // Drop the bad arp table listing and set it manually based on /sbin/ifconfig [gordon@ubuntu ~]$ sudo arp -d 192.168.135.101 [gordon@ubuntu ~]$ sudo arp -s 192.168.135.101 00:0B:6A:3A:30:A6 // Ping starts going thru..?!? [gordon@ubuntu ~]$ ping 192.168.135.101 PING 192.168.135.101 (192.168.135.101) 56(84) bytes of data. 64 bytes from 192.168.135.101: icmp_seq=1 ttl=64 time=15.8 ms 64 bytes from 192.168.135.101: icmp_seq=2 ttl=64 time=15.9 ms 64 bytes from 192.168.135.101: icmp_seq=3 ttl=64 time=16.0 ms 64 bytes from 192.168.135.101: icmp_seq=4 ttl=64 time=15.9 ms --- 192.168.135.101 ping statistics --- 4 packets transmitted, 4 received, 0% packet loss, time 3012ms rtt min/avg/max/mdev = 15.836/15.943/16.064/0.121 ms The following is my network config on this. gordon@db01:~$ /sbin/ifconfig eth0 Link encap:Ethernet HWaddr 00:0b:6a:3a:30:a6 inet addr:192.168.135.151 Bcast:192.168.135.255 Mask:255.255.255.0 inet6 addr: fe80::20b:6aff:fe3a:30a6/64 Scope:Link UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1 RX packets:15476725 errors:0 dropped:0 overruns:0 frame:0 TX packets:10030036 errors:0 dropped:0 overruns:0 carrier:0 collisions:0 txqueuelen:1000 RX bytes:18565307359 (17.2 GiB) TX bytes:3412098075 (3.1 GiB) eth0:0 Link encap:Ethernet HWaddr 00:0b:6a:3a:30:a6 inet addr:192.168.135.150 Bcast:192.168.135.255 Mask:255.255.255.0 UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1 eth0:1 Link encap:Ethernet HWaddr 00:0b:6a:3a:30:a6 inet addr:192.168.135.101 Bcast:192.168.135.255 Mask:255.255.255.0 UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1 eth1 Link encap:Ethernet HWaddr 00:e0:81:2a:6e:d0 inet addr:10.10.62.1 Bcast:10.10.62.255 Mask:255.255.255.0 inet6 addr: fe80::2e0:81ff:fe2a:6ed0/64 Scope:Link UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1 RX packets:10233315 errors:0 dropped:0 overruns:0 frame:0 TX packets:19400286 errors:0 dropped:0 overruns:0 carrier:0 collisions:0 txqueuelen:1000 RX bytes:1112500658 (1.0 GiB) TX bytes:27952809020 (26.0 GiB) Interrupt:24 lo Link encap:Local Loopback inet addr:127.0.0.1 Mask:255.0.0.0 inet6 addr: ::1/128 Scope:Host UP LOOPBACK RUNNING MTU:16436 Metric:1 RX packets:387 errors:0 dropped:0 overruns:0 frame:0 TX packets:387 errors:0 dropped:0 overruns:0 carrier:0 collisions:0 txqueuelen:0 RX bytes:41314 (40.3 KiB) TX bytes:41314 (40.3 KiB) gordon@db01:~$ sudo mii-tool -v eth0 eth0: negotiated 100baseTx-FD, link ok product info: Intel 82555 rev 4 basic mode: autonegotiation enabled basic status: autonegotiation complete, link ok capabilities: 100baseTx-FD 100baseTx-HD 10baseT-FD 10baseT-HD advertising: 100baseTx-FD 100baseTx-HD 10baseT-FD 10baseT-HD flow-control link partner: 100baseTx-FD 100baseTx-HD 10baseT-FD 10baseT-HD gordon@db01:~$ sudo route Kernel IP routing table Destination Gateway Genmask Flags Metric Ref Use Iface localnet * 255.255.255.0 U 0 0 0 eth0 10.10.62.0 * 255.255.255.0 U 0 0 0 eth1 default 192.168.135.1 0.0.0.0 UG 0 0 0 eth0

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  • Dhcpd Daemon is trying to lease itself?

    - by tommieb75
    I have a Slackware Linux 13.0 box with two interfaces, eth0 and eth1. I have set this box up to be on the 192.168.1.0/24 network, with subnet mask of 255.255.255.0. I am trying to run a dhcpd server on this box to service two interfaces above, so I subnetted the 192.168.1.0/24 network into two subnets. For eth0 192.168.1.1, subnet mask 255.255.255.128, broadcast mask 192.168.1.127. For eth1 192.168.1.129, subnet mask 255.255.255.128, broadcast mask 192.168.1.255. Both the interfaces are assigned manually. eth0 Link encap:Ethernet HWaddr 00:00:00:00:00:00 inet addr:192.168.1.1 Bcast:192.168.1.127 Mask:255.255.255.128 UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1 RX packets:0 errors:0 dropped:0 overruns:0 frame:0 TX packets:39 errors:0 dropped:0 overruns:0 carrier:0 collisions:0 txqueuelen:1000 RX bytes:0 (0.0 B) TX bytes:1404 (1.3 KiB) Interrupt:11 Base address:0x8000 Memory:faffc000-faffcfff eth1 Link encap:Ethernet HWaddr 00:00:00:00:00:00 inet addr:192.168.1.128 Bcast:192.168.1.255 Mask:255.255.255.128 UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1 RX packets:10003 errors:0 dropped:0 overruns:0 frame:0 TX packets:13286 errors:0 dropped:0 overruns:0 carrier:0 collisions:0 txqueuelen:1000 RX bytes:1589229 (1.5 MiB) TX bytes:9900005 (9.4 MiB) Interrupt:11 Here is the dhcpd.conf set up authoritative; ddns-update-style interim; ignore client-updates; subnet 192.168.1.0 netmask 255.255.255.128 { range 192.168.1.2 192.168.1.126; default-lease-time 86400; max-lease-time 86400; option routers 192.168.1.1; option ip-forwarding off; option domain-name-servers 208.67.222.222, 208.67.220.220; option broadcast-address 192.168.1.127; option subnet-mask 255.255.255.128; } subnet 192.168.1.128 netmask 255.255.255.128 { range 192.168.1.129 192.168.1.254; default-lease-time 86400; max-lease-time 86400; option routers 192.168.1.1; option ip-forwarding off; option domain-name-servers 208.67.222.222, 208.67.220.220; option broadcast-address 192.168.1.255; option subnet-mask 255.255.255.128; } This is what is showing in the log Apr 10 18:09:58 inspiron8600 dhcpd: DHCPDISCOVER from 00:00:00:00:00:00 (inspiron8600) via eth1 Apr 10 18:09:58 inspiron8600 dhcpd: DHCPOFFER on 192.168.1.131 to 00:00:00:00:00:00 (inspiron8600) via eth1 Apr 10 18:10:01 inspiron8600 dhcpcd[3832]: eth1: adding IP address 169.254.153.6/16 This is happening spuriously, and the log gets filled up with nonsense..so my question is this: How do I stop this from happening? And why would it be trying to give itself a lease? I am sure I have missed something but cannot see it and would appreciate a pair of eyes from the community to spot the obvious flaw!

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  • Transparent proxy which preserves client mac address

    - by A G
    I have a customer that wants to intercept SSL traffic as it leaves their network. My proposed solution is to setup a proxy that is transparent and both layer 2 and layer 3 so it can simply be dropped into their network without any change in config required. The proxy has two NICs, one connected to the server, the other to the client. The client, proxy and gateway are under control of the customer, the server is not. For example: client --- Proxy --- gateway -|- server I have my proxy program configured with IP_TRANSPARENT socket option to it can respond to connections destined for a remote IP. I am using the following setup: iptables -t mangle -A PREROUTING -p tcp --dport 80 -j TPROXY --on-port 3128 --tproxy-mark 1/1 iptables -t mangle -A PREROUTING -p tcp -j MARK --set-mark 1 ip rule add fwmark 1/1 table 1 ip route add local 0.0.0.0/0 dev lo table 1 The client in question is on its own subnet and has been configured so that the proxy is the default gateway. The result is: Client sends a frame to the proxy; source IP is client, source mac is client, destination IP is server, destination mac is proxy Proxy forwards this frame to the gateway; source IP is proxy, source mac is proxy, destination IP is server, destination mac is gateway Gateway forwards this to the server and gets a response back. Gateway sends reply back to proxy; source IP is server, source mac is gateway, destination IP is proxy, destination mac is proxy Proxy forwards this reply to client; source IP is server, source mac is proxy, destination IP is client, destination mac is client. The tproxy and iptables configuration lets the proxy send packets with a non local ip address. Is there a way to make something transparent at the mac address level? That is, put the client on the same subnet as the gateway. The gateway sees the source IP and mac as that of the client, even though they originated from the proxy. Could this be done by configuring the proxy as a bridge then use ebtables to escalate the traffic to be handled by iptables? When I use ebtables to push something up to iptables, it appears my proxy program doesn't respond to the packets as they are destined for the gateways's mac address, not the proxy's. What are some other potential avenues I could investigate? EDIT: When the client and gateway are on different subnets (and client has set the proxy as the gateway), it works as described in 1 to 5. But I want to know if it is possible to have the client and gateway on the same subnet and have the proxy fully transparent (ie client is not aware of the proxy). Thanks! EDIT 2: I can configure the proxy as a bridge using brctl, but cannot find a way to direct this traffic to my proxy program - asked here Possible for linux bridge to intercept traffic?. Currently, with the description numbered 1 to 5, it operates at layer 3; it is transparent on the client side (client thinks it is talking to the server's IP), but not on the gateway side (gateway is talking to the proxy's IP). What I want to find out is, is it possible to make this operate at layer 2, so it is fully transparent? What are the available options I should research? Thanks

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  • TCP stops sending weirdly.

    - by Utoah
    In case to find out the cause of TCP retransmits on my Linux (RHEL, kernel 2.6.18) servers connecting to the same switch. I had a client-server pair send "Hello" to each other every 200us and captured the packets with tcpdump on the client machine. The command I used to mimic client and server are: while [ 0 ]; do echo "Hello"; usleep 200; done | nc server 18510 while [ 0 ]; do echo "Hello"; usleep 200; done | nc -l 18510 When the server machine was busy serving some other requests, the client suffered from abrupt retransmits occasionally. But the output of tcpdump seemed irrational. 16:04:58.898970 IP server.18510 > client.34533: P 4531:4537(6) ack 3204 win 123 <nop,nop,timestamp 1923778643 3452833828> 16:04:58.901797 IP client.34533 > server.18510: P 3204:3210(6) ack 4537 win 33 <nop,nop,timestamp 3452833831 1923778643> 16:04:58.901855 IP server.18510 > client.34533: P 4537:4549(12) ack 3210 win 123 <nop,nop,timestamp 1923778646 3452833831> 16:04:58.903871 IP client.34533 > server.18510: P 3210:3216(6) ack 4549 win 33 <nop,nop,timestamp 3452833833 1923778646> 16:04:58.903950 IP server.18510 > client.34533: P 4549:4555(6) ack 3216 win 123 <nop,nop,timestamp 1923778648 3452833833> 16:04:58.905796 IP client.34533 > server.18510: P 3216:3222(6) ack 4555 win 33 <nop,nop,timestamp 3452833835 1923778648> 16:04:58.905860 IP server.18510 > client.34533: P 4555:4561(6) ack 3222 win 123 <nop,nop,timestamp 1923778650 3452833835> 16:04:58.908903 IP client.34533 > server.18510: P 3222:3228(6) ack 4561 win 33 <nop,nop,timestamp 3452833838 1923778650> 16:04:58.908966 IP server.18510 > client.34533: P 4561:4567(6) ack 3228 win 123 <nop,nop,timestamp 1923778653 3452833838> 16:04:58.911855 IP client.34533 > server.18510: P 3228:3234(6) ack 4567 win 33 <nop,nop,timestamp 3452833841 1923778653> 16:04:59.112573 IP client.34533 > server.18510: P 3228:3234(6) ack 4567 win 33 <nop,nop,timestamp 3452834042 1923778653> 16:04:59.112648 IP server.18510 > client.34533: P 4567:5161(594) ack 3234 win 123 <nop,nop,timestamp 1923778857 3452834042> 16:04:59.112659 IP client.34533 > server.18510: P 3234:3672(438) ack 5161 win 35 <nop,nop,timestamp 3452834042 1923778857> 16:04:59.114427 IP server.18510 > client.34533: P 5161:5167(6) ack 3672 win 126 <nop,nop,timestamp 1923778858 3452834042> 16:04:59.114439 IP client.34533 > server.18510: P 3672:3678(6) ack 5167 win 35 <nop,nop,timestamp 3452834044 1923778858> 16:04:59.116435 IP server.18510 > client.34533: P 5167:5173(6) ack 3678 win 126 <nop,nop,timestamp 1923778860 3452834044> 16:04:59.116444 IP client.34533 > server.18510: P 3678:3684(6) ack 5173 win 35 <nop,nop,timestamp 3452834046 1923778860> Packet 3228:3234(6) from client was retransmitted due to ack timeout. What I could not understand was that the client machine did not send out any packets after the first 3228:3234(6) packets was sent. The server machine had advertised a window (scaled) large enough. The data transfer up to the retransmit was fine which meant no slow start should be in action. What can cause the client machine to stop sending until the packet timed out? BTW, I am unable to run tcpdump on the server machine.

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