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  • What is the advantage of iSCSI over SMB?

    - by sofakng
    At my house I'm running a Hyper-V server with a Windows Server 2008 R2 VM acting as a file server. Files are shared across my network using SMB. (Also, the machine is using a PERC 6/i RAID card but I don't think that's important) I'm thinking about setting up a dedicated SAN (iSCSI) machine and then switching my Hyper-V server to ESXi. What are the advantages of using iSCSI versus SMB? I think I would still need a file server OS (eg. Win 2k8) sharing files via SMB so I'm not sure the end result would be any different than my current setup...

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  • Finding a private (NAT) host's IP using historic destination data

    - by l0c0b0x
    The issue: An unknown private (NAT) client is infected with malware and it's trying to access a Bot server at random times/dates. How we know about this: We receive bot traffic notices/alerts from REN-ISAC. Unfortunately, we don't receive those until the next day after it has happened. What they provide to us is: The source address (of the firewall) The destination addresses (it varies, but they're going to network subnet allocated to a German ISP) The source port (which varies--dynamic ports). Question: What would be the best approach to finding this internal host (historically) with a Cisco ASA as firewall? I'm guessing blocking anything to the destination address(es), and logging that type of traffic/access might allow me to find the source host, but I'm not sure which tool/command would be the most useful. I've seen Netflow thrown into a few responses when it comes to logging, but I'm confused with it's association of Logging, NAL, and nBAR, and how they relate to Netflow.

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  • Assign fixed IP address via DHCP by DNS lookup

    - by Janoszen
    Preface I'm building a virtualization environment with Ubuntu 14.04 and LXC. I don't want to write my own template since the upgrade from 12.04 to 14.04 has shown that backwards compatibility is not guaranteed. Therefore I'm deploying my virtual machines via lxc-create, using the default Ubuntu template. The DNS for the servers is provided by Amazon Route 53, so no local DNS server is needed. I also use Puppet to configure my servers, so I want to keep the manual effort on the deployment minimal. Now, the default Ubuntu template assigns IP addresses via DHCP. Therefore, I need a local DHCP server to assign IP addresses to the nodes, so I can SSH into them and get Puppet running. Since Puppet requires a proper DNS setup, assigning temporary IP addresses is not an option, the client needs to get the right hostname and IP address from the start. Question What DHCP server do I use and how do I get it to assign the IP address based only on the host-name DHCP option by performing a DNS lookup on that very host name? What I've tried I tried to make it work using the ISC DHCP server, however, the manual clearly states: Please be aware that only the dhcp-client-identifier option and the hardware address can be used to match a host declaration, or the host-identifier option parameter for DHCPv6 servers. For example, it is not possible to match a host declaration to a host-name option. This is because the host-name option cannot be guaranteed to be unique for any given client, whereas both the hardware address and dhcp-client-identifier option are at least theoretically guaranteed to be unique to a given client. I also tried to create a class that matches the hostname like this: class "my-client-name" { match if option host-name = "my-client-name"; fixed-address my-client-name.my-domain.com; } Unfortunately the fixed-address option is not allowed in class statements. I can replace it with a 1-size pool, which works as expected: subnet 10.103.0.0 netmask 255.255.0.0 { option routers 10.103.1.1; class "my-client-name" { match if option host-name = "my-client-name"; } pool { allow members of "my-client-name"; range 10.103.1.2 10.103.1.2; } } However, this would require me to administer the IP addresses in two places (Amazon Route53 and the DHCP server), which I would prefer not to do. About security Since this is only used in the bootstrapping phase on an internal network and is then replaced by a static network configuration by Puppet, this shouldn't be an issue from a security standpoint. I am, however, aware that the virtual machine bootstraps with "ubuntu:ubuntu" credentials, which I intend to fix once this is running.

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  • What would cause Memcached to Hang for 2+ seconds?

    - by Brad Dwyer
    I'm going nuts trying to scale memcached. From their site: Memcached operations are almost all O(1). Connecting to it and issuing a get or stat command should never lag. If connecting lags, you may be hitting the max connections limit. See ServerMaint for details on stats to monitor. If issuing commands lags, you can have a number of tuning problems. Most common are hardware problems, not enough RAM (swapping), network problems (bandwidth, dropped packets, half-duplex connections). On rare occasion OS bugs or memcached bugs can contribute. Well.. it is most certainly not performing like an O(1) operation for me. Under low to normal load on our site memcached response times for get and set ops are about 0.001 seconds. Not bad. But if we triple the load we get outliers that take 100x (or in rare cases 1000x!) that long. I even had one instance where it took 2.2442 seconds for memcached to store a value. Obviously this is killing our site. Here's the output of Memcached-getStats during one of the slow periods: [pid] => 18079 [uptime] => 8903 [threads] => 4 [time] => 1332795759 [pointer_size] => 32 [rusage_user_seconds] => 26 [rusage_user_microseconds] => 503872 [rusage_system_seconds] => 125 [rusage_system_microseconds] => 477008 [curr_items] => 42099 [total_items] => 422500 [limit_maxbytes] => 943718400 [curr_connections] => 84 [total_connections] => 4946 [connection_structures] => 178 [bytes] => 7259957 [cmd_get] => 1679091 [cmd_set] => 351809 [get_hits] => 1662048 [get_misses] => 17043 [evictions] => 0 [bytes_read] => 109388476 [bytes_written] => 3187646458 [version] => 1.4.13 So things that I have ruled out so far are: Hitting the max connections limit (curr_connections of 84 is well below the default of max of 1024) Swapping - the machine has 900M out of 1024M of memory dedicated to memcached on a dedicated machine. It only appears to be using about 7MB of data as per the bytes stat. How would I diagnose the other hardware problems? prstat doesn't really show a whole lot going on in terms of CPU or memory usage. Not sure how to figure out the network problems but as this is a dedicated server on the same private network as the web box I don't think it's a connectivity issue (ping is less than a millisecond between the boxes). Is there something else I'm missing here? It's driving me nuts. Edit: Also forgot to mention that I've tried both persistent and non-persistent connections with minimal-to-no impact.

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  • Get the wireless adapter frequency-band mode in Windows 7

    - by Petr
    I have a dual-band 802.11n router operating in both frequency bands with the same SSID. My Windows 7 laptop has a dual-band wireless adapter. Is there a way to find out which frequency band is the one currently used by the client? Also, is there a way to set the preffered band? Thanks. EDIT1: The router is Linksys E4200 (V2) and I essentially want to keep the 2.4GHz band in the mixed-mode so that the legacy 802.11g devices can connect while allocating the 5.0GHz band for 802.11n devices. The laptop's adapter (Intel Centrino Ultimate-N 6300 ANG) can operate in both 802.11n modes. EDIT2: Related topic

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  • Redirection of outbound UDP port NTP.

    - by pboin
    For my residential service, I changed ISPs to Zoom/Armstrong. Just after that, my NTP daemons stopped working. I dug deep and diagnosed the problem: Unprivileged ports are getting out. When i run 'ntpdate' for example, I go out on a high, unprivleged port, and get a response on UDP 123. That's fine. The 'ntpd' daemon though, expects to go out on 123 and get its reply there as well. This must be a common problem, because it's directly addressed in the NTP troubleshooting guide. Just to see what would happen, I wrote a detailed email to the general support address at Armstrong. They replied almost immediately with a complete technical answer! They have everything <1024 blocked, except for a few ports to support outbound VPN. So, the question: Can I use IPtables to essentially re-write my outbound UDP 123 up to 2123 or something like that? If I do, does there need to be a corresponding 2123-123 rule to translate the reply? This seems like NAT, but with ports, not addresses. True, I could run ntpdate from cron, but that loses all of the adjustment smarts of NTP.

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  • Why does my Intel Tolapai network chip not transmit packets?

    - by Hanno Fietz
    I'm trying to deploy an embedded system (NISE 110 by Nexcom) based on the Intel EP80579 (Tolapai) chip. Tolapai apparently integrates controllers for Ethernet etc. on a single chip (Intel homepage). The machine can't get a network connection. Diagnosis as far as I could manage: Drivers drivers from Intel compiled and installed without problems (version 1.0.3-144). Kernel version and Linux distribution (CentOS 5.2, 2.6.18) match the driver's installation instructions. drivers are loaded and show up in lsmod (module names are gcu and iegbe) interfaces eth0 and eth1 show up in ifconfig ifconfig I can bring up the interfaces with fixed IP pinging the interface locally works ifconfig shows flag UP but not RUNNING Link ethtool shows "Link detected: no", "Speed: unknown (65536)" and "Duplex: unknown (255)" Link LED is on on the other side of the cable, ethtool shows "Link detected: yes" and reports a speed of 1000 Mbps, which has allegedly been auto-neogotiated with the problematic device. Network traffic analysis the device does not reply on ARP, ICMP echo or anything else (iptables is down) when trying to send ICMP or DHCP requests, they never reach the other end activity LED is off on the device, on at the other end. I tried the following without any effect: Different cables (2 straight, one crossed), I get the link LED lit up on each. Three different devices on the other end (one PC, one netbook, one router) Fixed ARP table entries on both sides Connecting both network ports of the machine with each other, won't ping through the cable, but will ping locally. Tried straight and crossed cables for that.

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  • Computer name not appearing on network

    - by stib
    I can connect to other computers on my home network (ubuntu + OSX machines) using the IP address, but I can't connect using the netbios name. On the mac the name appears in Finder but if I try to connect (goconnect to server smb://[email protected]) it doesn't work, while smb://[email protected] does. Same with ssh, ping and afp between the macs. This is a intermittent problem. It has worked in the past.

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  • Slow LAN transfer from 3rd party computer

    - by Chris
    Hi Everyone, I've got an odd problem that I'm not really sure where to start the troubleshooting process. I have a 'server' with Windows Server 2008R2 (64-bit) installed and it has a couple of hard drives. If I Remote Desktop into the server and transfer files from one HD to the other, all it fine. If however, I use my workstation (Windows 7 64bit) and open up a shared resource on the server and transfer a file from one hard drive on the server to another HD on the server (not using Remote Desktop, just Windows explorer/Network places), the transfer crawls... It takes about 5mins to discover files/calculate the transfer and then starts transferring at speeds like 56KB/s - 200KB/s. Both machines have Marvel GigE network ports with a TrendNet 8-port green GigE switch. I've set Jumbo packets to 9K on both machines...

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  • File property information (last write time and file size) in explorer out of date by hours over netw

    - by David L Morris
    An application is running on a windows XP prof machine picking up file from a network share from another windows machine. It detects that the file has been updated (by date and time or optionally file size) and reads it for any new data. Most of the time the last write time and file size, seems to be up to date. Occasionally, this information stops being updated, even though the file is growing (intermittently during the day) with appended content, so that the last write time and file size remain fixed at some arbitrary moment. This is visible in explorer, where it shows a fixed last write time on the reading machine. Just opening the file to edit it in notepad, immediately refreshes the file properties, and the other application picks up where it left of. The file location can't be changed, nor the location of the relevant applications. Any solutions to resolve this problem?

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  • What are some good, IP Address Management solutions for IPv6? [closed]

    - by Russell Heilling
    There are a number of open source IPAM tools available for IPv4 address management; however there seems to be a distinct lack of actively updated tools available for IPv6. Other than FreeIPdb (code no longer maintained) or the RIPE Database (I have seen some customisations to the RIPEdb that allow for enterprise/ISP IPAM but it seems like overkill for a system that will probably only ever handle one /32 worth of space). Are there any other options that I'm missing? (Database only please. I know vi can be used for flat text IPAM, that's how I'm handling our /32 at the moment, but I don't see it scaling for much longer) It doesn't have to be open source but what are folks doing to manage IPv6 in a dual stack environment

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  • Building a Mac/PC Network in a Dorm with Network Restrictions

    - by user70340
    I have been a Windows XP user for the last few years, but I recently bought a 15'' MacBook Pro for research purposes. I would like to set up a no-hassle Mac/PC Network at home so that I can access the internet on both computers and hardware between computers (i.e. a harddrive, or a mouse/keyboard with Synergy). Unfortunately, I live in a dorm with silly network restrictions so a solution is not straightforward. In particular: The dorm has a wired and wireless network, both which provide an internet connection. The wired network provides way faster internet (download speeds of 15 MB/s vs. 2 MB/s on wireless), so I would like to somehow exploit this, at least on my PC for Bittorrent :) Multiple devices can connect to the wireless network, but cannot "see" each other on the network (so software like Synergy would not work). Only 1 MAC address can connect to the wired network at a time. Ideally I would just connect a wireless router to the wired network and then have both the Mac and the PC on that, but the 1 MAC address restriction will not allow the both computer to access the internet simultaneously. I cannot think of a way to bypass this restriction (though I'm not network savvy), so I am planning to create a private no-internet network to allow the devices to see each other and share hardware. Here are some thoughts. I would appreciate any feedback at all! If I build a private wireless network: (first choice) I will use a wireless router that is not connected to the internet. My PC and Mac will be connected to each other wirelessly. I can then connect the PC to the internet via a wired network, but then the Mac will not have internet access as its wireless card is already in use. In this case, could I stream internet access from the PC to the Mac via the wireless network? Or could I buy a USB wireless card for the Mac so that it can connect to both my private network and the dorm network? If I build a private wired network: (second choice) Then both the PC and the Mac will connect to the internet wirelessly, which means I cannot take advantage of the faster download speeds.

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  • Tunneling a public IP to a remote machine

    - by Jim Paris
    I have a Linux server A with a block of 5 public IP addresses, 8.8.8.122/29. Currently, 8.8.8.122 is assigned to eth0, and 8.8.8.123 is assigned to eth0:1. I have another Linux machine B in a remote location, behind NAT. I would like to set up an tunnel between the two so that B can use the IP address 8.8.8.123 as its primary IP address. OpenVPN is probably the answer, but I can't quite figure out how to set things up (topology subnet or topology p2p might be appropriate. Or should I be using Ethernet bridging?). Security and encryption is not a big concern at this point, so GRE would be fine too -- machine B will be coming from a known IP address and can be authenticated based on that. How can I do this? Can anyone suggest an OpenVPN config, or some other approach, that could work in this situation? Ideally, it would also be able to handle multiple clients (e.g. share all four of spare IPs with other machines), without letting those clients use IPs to which they are not entitled.

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  • Finding Missing UDP Frames Using Wireshark + Custom Dissector (for CQS)

    - by John Dibling
    How do you use Wireshark to identify missing UDP frames? I have written a custom dissector for the CQS feed (reference page). One of our servers gaps when receiving this feed. According to Wireshark, some UDP frames are never received. I know that the frames were sent because all of our other servers are gap-free. A CQS frame consists of multiple messages, each having its own sequence number. My custom dissector provides the following data to Wireshark: cqs.frame_gaps - the number of gaps within a UDP frame (always zero) cqs.frame_first_seq - the first sequence number in a UDP frame cqs.frame_expected_seq - the first sequence number expected in the next UDP frame cqs.frame_msg_count - the number of messages in this UDP frame And I am displaying each of these values in custom columns, as shown in this screenshot: A typical CQS log will consist of millions of rows, so I can't just eyeball it. Is there any way I can get Wireshark to tell me which frames are missing?

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  • Blocked connections passing through firewall. What is wrong?

    - by Kiranu
    In our company we have a small business router (Cisco RV082) on which we are using its standard configuration (block all incoming traffic). We also have an SMTP relay configured (using WS2008R2) so that our internal applications can send email through google apps (which requires authentication). The thing is that the server was being used to send spam. We fixed the problem by only allowing the server to relay email from our internal IP address range (10.0.0.0/16). My concern is that there was a way by which external IPs connected to the network and that underlying problem has not been fixed, but I cannot imagine how these machines connected. Any thoughts?

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  • How can I switch from a custom linux network namespace back to the default one?

    - by Martin
    With ip netns exec you can execute a command in a custom network namespace - but is there also a way to execute a command in the default namespace? For example, after executing these two commands: sudo ip netns add test_ns sudo ip netns exec test_ns bash How can the newly created bash execute programs in the default network namespace? There is no ip netns exec default or anything similar as far as I've found. My scenario is: I want to run a SSH server in a separate network namespace (to keep the rest of the system unaware of the network connection, as the system is used for network testing), but want to be able to execute programs in the default network namespace via the SSH connection. What I've found out so far: Created network namespaces are listed as files under /var/run/netns (but there is no file for the default namespace) The ip netns exec code can be found here: http://git.kernel.org/cgit/linux/kernel/git/shemminger/iproute2.git/tree/ip/ipnetns.c#n132 - I haven't grasped everything that it is doing yet, but it doesn't look very promising. ip netns identify $$ as suggested by Howto query and change network namespace on linux? returns nothing when in the default network namespace

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  • SASL - Plaintext password not accepted - Encrypted works

    - by leviathanus
    I have a very strange issue! SASL does not work properly, as it does not accept plain-text passwords (like Outlook sends them) Oct 2 10:35:09 srf cyrus/imap[4119]: accepted connection Oct 2 10:35:09 srf cyrus/imap[4119]: badlogin: [217.XX.XXX.140] plaintext [email protected] SASL(-1): generic failure: checkpass failed Now I switch to "Encrypted password" in Thunderbird. I have the same issue as Outlook above on Thunderbird if I turn on "Plain Password"): Oct 2 10:40:40 srf cyrus/imap[14644]: accepted connection Oct 2 10:40:41 srf cyrus/imap[14622]: login: [217.XX.XXX.140] [email protected] CRAM-MD5 User logged in Same with Postfix: Without Oct 2 10:42:48 srf postfix/smtpd[17980]: connect from unknown[217.XX.XXX.140] Oct 2 10:42:48 srf postfix/smtpd[17980]: warning: SASL authentication failure: cannot connect to saslauthd server: Permission denied Oct 2 10:42:48 srf postfix/smtpd[17980]: warning: SASL authentication failure: Password verification failed Oct 2 10:42:48 srf postfix/smtpd[17980]: warning: unknown[217.XX.XXX.140]: SASL PLAIN authentication failed: generic failure With "Encrypted password": Oct 2 10:45:27 srf postfix/smtpd[21872]: connect from unknown[217.XX.XXX.140] Oct 2 10:45:28 srf postfix/smtpd[21872]: 50B3A332AAB: client=unknown[217.XX.XXX.140], sasl_method=CRAM-MD5, [email protected] Oct 2 10:45:28 srf postfix/cleanup[21899]: 50B3A332AAB: message-id=<[email protected]> Oct 2 10:45:28 srf postfix/qmgr[6181]: 50B3A332AAB: from=<[email protected]>, size=398, nrcpt=1 (queue active) Oct 2 10:45:28 srf postfix/smtpd[21872]: disconnect from unknown[217.XX.XXX.140] Config: /etc/imapd.conf:sasl_mech_list:LOGIN PLAIN CRAM-MD5 and /etc/postfix/sasl/smtpd.conf:mech_list: LOGIN PLAIN CRAM-MD5 I have no idea where to dig. Please advise.

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  • VLAN for WiFi traffic separation (new to VLANing)

    - by Philip
    I run a school network with switches in different departments. All is routed through to a central switch to access the servers. I would like to install WiFi access points in the different departments and have this routed through the firewall (an Untangle box that can captive-portal the traffic, to provide authentication) before it gets onto the LAN or to the Internet. I know that the ports that the APs connect to on the relevant switches need to be set to a different VLAN. My question is how do I configure these ports. Which are tagged? Which are untagged? I obviously don't want to interrupt normal network traffic. Am I correct in saying: The majority of the ports should be UNTAGGED VLAN 1? Those that have WiFi APs attached should be UNTAGGED VLAN 2 (only) The uplinks to the central switch should be TAGGED VLAN 1 and TAGGED VLAN 2 The central switch's incoming ports from the outlying switches should also be TAGGED VLAN 1 and TAGGED VLAN 2 There will be two links to the firewall (each on its own NIC), one UNTAGGED VLAN 1 (for normal internet access traffic) and one UNTAGGED VLAN 2 (for captive portal authentication). This does mean that all wireless traffic will be routed over a single NIC which will also up the workload for the firewall. At this stage, I'm not concerned about that load.

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  • Is Winpcap able to capture all packets going through a Gigabit NIC without missing any packets?

    - by Patrick L
    I want to use Winpcap to capture all network packets going through a Gigabit NIC of a server. Assuming that I am able to utilize the network link up to 100%, the maximum network speed is 1000Mbps. If we exclude the TCP/IP headers, the maximum TCP data rate should be roughly 940Mbps. Let's say I send a 1GB file through the NIC at 940Mbps using TCP destination port 6000. I use Winpcap to capture all network packets going through the NIC and then dump it to a pcap file. If I use Wireshark to analyze the pcap file and then check the sum of packet size for all network packets sent to TCP port 6000, am I able to get exactly 1GB from the pcap file? Thanks.

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  • Transient network dropout for Xen DomU's

    - by Stephen C
    We've got a CentOS server running a cluster of virtuals. Occasionally the cluster's internal network drops out for a minute or so ... and then comes back. The problem is somehow related to the actual network traffic, but it is not a simple load issue. (The system is generally lightly loaded, and the problem occurs irrespective of actual load.) The setup: CentOS 5.6 on Dom0, various CentOS on the DomU's Hardware - a Dell R710 with a BroadCom NextXpress 2 NIC (sigh) using the latest drivers for the NIC from BroadCom Xen configured to use network-bridge and vif-bridge Some iptable tweaks to route an unrelated port to one of the virtuals. The system has one externally visible IP address, and Dom0 runs an Apache httpd configured with a number of virtual hosts each of which reverse proxies to web servers running on the virtuals. (The virtuals have to be NAT'ed, primarily because we don't have enough allocated public IP addresses.) The symptoms: Works fine most of the time. When someone tries to UPLOAD a large file to one virtuals, the internal network drops out ... for all virtuals: The Dom0 httpd sees a network timeout talking to the backend server on the virtual and reports a 502. A previously established ssh connection from Dom0 to any of the DomU's freezes. Our monitoring shows ping failures for traffic between virtuals. The Xen consoles to the DomU's do not freeze. No log messages in any log files that I can see, on either Dom0 or the DomU's ... apart from the Dom0 httpd logs. After a minute or so, the problem clears by itself. This is 100% reproducible. What we've tried: Downloading, building and installing the latest BNX2 driver on Dom0 Turning off MSI on the NIC - adding "options bnx2 disable_msi=1" to /etc/modprobe.conf Turning off tcp segmentation offload - "ethtool -K eth0 tso off". Sacrificing a black rooster at midnight. I've exhausted all my options apart from switching to KVM ... or slaughtering more roosters. Any suggestions?

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  • TC hashing filters - single rule deletion

    - by exa
    For traffic shaping I'm currently using a setup that looks exactly like the setup from LARTC, on this page: http://lartc.org/howto/lartc.adv-filter.hashing.html I have a simple problem with that - everytime I want to modify something in the hash table (like assign a IP to different flowid), I need to delete the whole filter table and add it again filter by filter. (I actually don't do it by hand, I have a nice program that does it for me... but still...) There is a problem - I got roughly 10k filters allocated this way and deleting and refilling the whole filtertable can get pretty lengthy, which is not exactly good for traffic shaping. My program could easily manage to delete only the rules that need to be deleted (thus reducing the whole problem to several commands and miliseconds), but I simply don't know the command that deletes only the one hashing rule. My tc filter show: filter parent 1: protocol ip pref 1 u32 filter parent 1: protocol ip pref 1 u32 fh 2: ht divisor 256 filter parent 1: protocol ip pref 1 u32 fh 2:a:800 order 2048 key ht 2 bkt a flowid 1:101 match 0a0a0a0a/ffffffff at 16 filter parent 1: protocol ip pref 1 u32 fh 2:c:800 order 2048 key ht 2 bkt c flowid 1:102 match 0a0a0a0c/ffffffff at 16 filter parent 1: protocol ip pref 1 u32 fh 800: ht divisor 1 filter parent 1: protocol ip pref 1 u32 fh 800::800 order 2048 key ht 800 bkt 0 link 2: match 00000000/00000000 at 16 hash mask 000000ff at 16 The wish: 'tc filter del ...' command that removes only one specific filter (for example the 0a0a0a0a IP match (IP address 10.10.10.10)). Removal of some small subgroup would also be good - for example I could still recreate a bucket (bkt a) pretty fast. My attempts: I tried to number all the filters using prio, but with no help -- they just create something unusuable (but deletable) below, but the bucketed filters remain there after that gets deleted. Any ideas? edit - I'm adding a simplified tl;dr description of the problem: I created hash filter on some interfce just like in this http://lartc.org/howto/lartc.adv-filter.hashing.html I want to find a command that deletes one rule (e.g. 1.2.1.123) from the table, leaving the rest untouched and working.

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  • IPC between multiple processes on multiple servers

    - by z8000
    Let's say you have 2 servers each with 8 CPU cores each. The servers each run 8 network services that each host an arbitrary number of long-lived TCP/IP client connections. Clients send messages to the services. The services do something based on the messages, and potentially notify N1 of the clients of state changes. Sure, it sounds like a botnet but it isn't. Consider how IRC works with c2s and s2s connections and s2s message relaying. The servers are in the same data center. The servers can communicate over a private VLAN @1GigE. Messages are < 1KB in size. How would you coordinate which services on which host should receive and relay messages to connected clients for state change messages? There's an infinite number of ways to solve this problem efficiently. AMQP (RabbitMQ, ZeroMQ, etc.) Spread Toolkit N^2 connections between allservices (bad) Heck, even run IRC! ... I'm looking for a solution that: perhaps exploits the fact that there's only a small closed cluster is easy to admin scales well is "dumb" (no weird edge cases) What are your experiences? What do you recommend? Thanks!

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  • [tcpdump] Proxy delegate refusing connexion ?

    - by simtris
    Hi guys, I'm a little disapointed ! My aim was to build a VERY simple smtp proxy under debian to handle mail from a port (51234) and forward it to the standard 25 port. I compile and install a "delegate" witch can handle easily that. It's working very well like that : delegated SERVER="smtp://anotherSmtpServer:25" -P51234 The strange thing is, it's working on my virtual test machine and on the dedicated server in local but I can't manage to use it trought internet. I test it like that. telnet [mySrv] 51234 Of course, no firewal, no deny host, no ined/xined, the service delegated is listening on the right port ... 2 clues : The port is answering trought internet with nmap as "51234/tcp open tcpwrapped" have a look at the tcpdump following : 22:50:54.864398 IP [myIp].1699 [mySrv].51234: S 2486749330:2486749330(0) win 65535 22:50:54.864449 IP [mySrv].51234 [myIp].1699: S 2486963525:2486963525(0) ack 2486749331 win 5840 22:50:54.948169 IP [myIp].1699 [mySrv].51234: . ack 1 win 64240 22:50:54.965134 IP [mySrv].43554 [myIp].auth: S 2485396968:2485396968(0) win 5840 22:50:55.243128 IP [myIp] [mySrv]: ICMP [myIp] tcp port auth unreachable, length 68 22:50:55.249646 IP [mySrv].51234 [myIp].1699: F 1:1(0) ack 1 win 46 22:50:55.309853 IP [myIp].1699 [mySrv].51234: . ack 2 win 64240 22:50:55.310126 IP [myIp].1699 [mySrv].51234: F 1:1(0) ack 2 win 64240 22:50:55.310137 IP [mySrv].51234 [myIp].1699: . ack 2 win 46 The part "auth" seems suspect to me but didn't ring a bell. I could certaily do with some help. Thx a lot !

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