• How to use the FTDI USB serial cable to RJ45 adapter to connect to the console on Cisco/Juniper Switch Router Firewall in Linux Ubuntu Debian Redhat


    This should work for most console ports of other manufacturers too. It is a quick and simple method for emegencies or deploying a few appliances/devices in a non-standard environment or small environment. However, if this is a route thing, or the equipment is not physically close to you, it would be best to use some sort of "Terminal" server which is an IP connected switch with several serial ports built-in for this purpose. Normally they accessible by web/........
  • PXE-E23 Error BOOTx64.EFI GRUB booting is 0 bytes tftp pxe dhcp solution NBP filesize is 0 Bytes


    Be very careful about what filename you specify in dhcpd.conf if you get an error like this: NBP filesize is 0 Bytes PXE-E23:Client received TFTP error from server. If you specify "BOOTx64.efi" then the file had better not be called "BOOTx64.EFI" as it is case sensitive. It's really a case of th........
  • Virtualbox Best Networking Mode In Lab/Work Environment without using NAT Network or Bridged


    Virtualbox is a very powerful tool, but for some use cases it is less than optimal. Say you are in a work, lab or other environment where you are not alone on the physical network and there could be overlap of IPs, but you need all of your VMs to be contactable from your host, VMs need to communicate with each other, and VMs need internet. NAT Network will give you VM to VM communication and internet, however, it is buggy and unstable. It also doesn't allow host to VM co........
  • Grandstream Phone Vulnerability Security Issue Remote Backdoor Connection to 207.246.119.209:3478


    Have you checked your router/firewall logs and disconcertingly see connections to an unknown IP207.246.119.209:3478 from your Grandstream VOIPphones? You're not alone and the Grandstream forums have discussed this issue. However, even their own staff d........
  • Cisco UC CME How To Enable Licensed Features


    Router#show license Index 1 Feature: ipbasek9 Period left: Life time License Type: Permanent License State: Active, In Use License Count: Non-Counted Lic........
  • Cisco Switch / Router How To Restore Factory Default Settings


    1.) Make sure your conf register is 0x2102 Do show version and at the very end of the output you will see the Configuration register. show version Configuration register is 0x2102 If the config register is not 0x2102 then enter this command: r1#configure terminal r1(config)#config-register 0x2102 r1(config)#end 2.) Let's Erase the NVRAM/flash........
  • Cisco 2900 3900 Router Password Reset How To Reset Enable Password


    It is a bit different and annoying here for these types of routers/models as you need to physically remove the CF (Compact Flash) and only then, will it enter ROMMON mode (Ctrl + Pause remotely over the console will not do it for us). This means you cannot do this remotely, or at least not without the help of a remote/physical helper. Step 1.) Power off, router and remove CF Disk Slot#2 Go to the router and remove the slot#2 cover uses your hand or it may help to use a........
  • Translating "cisco" ...domain server (255.255.255.255) Cisco Router/Switch Solution


    If you are in enable mode and make a typo, the router will treat it as a domain name and try to resolve it, and if it can't resolve it, you'll have to wait until it times out. Here's how to solve the Translating domain server error in Cisco Enter this in config mode: no ip domain-lookup Be sure to sav........
  • Error opening tftp://10.0.2.2/network-confg (Permission denied) - How To Fix Cisco Router Switch Error Solution Console


    How To Fix This Cisco Switch/Router Error %Error opening tftp %Error opening tftp://10.0.2.2/network-confg (Permission denied) %Error opening tftp://10.0.2.2/cisconet.cfg (Permission denied) %Error opening tftp://10.0.2.2/router-confg (Permission denied) %Error opening tftp://10.0.2.2/ciscortr.cfg (Permission denied) %Error opening tftp://10.0.2.2/network-confg (Perm........
  • Loaded: masked (Reason: Unit hostapd.service is masked.) Solution in Linux Debian Mint Ubuntu


    If you are getting this error from systemctl "Loaded: masked (Reason: Unit hostapd.service is masked.)" we need to unmask the service. Solution systemctl unmask hostapd Removed /etc/systemd/system/hostapd.service. It's fixed root@routerOS:/var/log# systemctl start hostapd root@routerOS:/var/log# systemctl status hostapd ● hostapd.service - Access point and authentication server for Wi-Fi and Ethern........
  • Debian Ubuntu Mint DHCP dhclient quits and how to make it persistent if first attempt to get DHCP lease fails


    Debian based OS's have a similar issue as the behavior in RHEL/CentOS dhclient, which is that if you have an interface that relies on DHCP, if the first attempt fails, it will quit and stop. This is a problem especially if you are using your Linux as a router or something else mission critical, but where the internet for some reason may have been down or the DHCP server it gets a lease from broken. The expected behavior you would hope is that when things are back online that the........
  • How To Create OpenVPN Server for Secure Remote Corporate Access in Linux Debian/Mint/Ubuntu with client public key authentication


    Why choose OpenVPN instead of a firewall appliance? OpenVPN can be a reliable and easy replacement for traditional hardware or just be an additional tool that your company uses so that the firewall can focus on its job rather than acting as a VPNappliance at the same time. When comparing OpenVPN with traditional firewal........
  • Cisco Howto Configure Console Port/Terminal/Comm Server with Async Cable Setup


    This assumes that you've already installed the relevant HWIC cards eg. Cisco Asynchronous Serial NIM These are essentially cards that you install into your router, once installed you connect an Async cable to one of the ports on the card which normally gives you 8 console cables and are normally labelled 1 through 8. You connect all of the cables to the devices you need (even non-Cisco devices) whether switches, routers or firewalls, they will usually work. The real m........
  • SSH cannot connect to old servers/devices/switches/routers/Cisco/Juniper Unable to negotiate with 192.168.20.2 port 22: no matching key exchange method found. Their offer: diffie-hellman-group-exchange-sha1,diffie-hellman-group14-sha1,diffie-hell


    A lot of older devices either support telnet or very old SSH keyx algorithms which are insecure and disabled by all newer/modern SSH clients for security reasons. However, sometimes you may be on a LAN via VPNor some other secured network or for whatever reason, absolutely, need to connect to this device and sometimes old/embedded devices may not be possible to update to a newer SSH server. If you run into this you may be using a modern/newer SSH client and get thi........
  • Cisco Router Password Reset Howto Guide Solution Cannot Login /Unknown Enable Password 2600, 2800, 2900, 3900


    It is common that you may get access to undocumented equipment and need to reset the password. This applies to many Cisco routers whether 2600, 2900, 3900 etc... Cisco's Guide says to hit Ctrl +Pause/Break but if it doesn't work on some devices causing people to say "cisco password reset pause break does not work", you can see Cisco's alternative key combinations here:........
  • EFI PXE grub2 Howto guide for Linux EFI PXE Booting on Debian, Mint, Ubuntu, RHEL


    Just a quick note and warning is that if you are testing to see if EFIPXE booting works on a VM, MAKE SURE it actually works. For example Iinitially tested using my Distro's QEMU 2.5+dfsg-5ubuntu10.46 and ovmf BIOS firmware (OVMF supports EFI). However, I found on old versions of QEMU (like 2.5), EFIbooting with GRUB NEVER works so it may appear that you have made a mistake when everything is fine when you boot a physi........
  • Juniper JunOS Command Overview and Howtos Switch, Router, Firewall Tutorial Guide


    Enable "cli" mode equivalent in JunOS cli Configure Mode configure So rather than going to the console on a Cisco switch and typing "enable" and then "conf t", the equivalent in JunOS is "cli" and "configure". How Do You Apply Changes You've Made? You can make all kinds of changes to the switch, but remember they are not........
  • Mikrotik RouterOS CHR/ISO Basic and Quick Setup Howto Guide


    Many people may not be aware that you can turn commodity hardware into a Mikrotik OS and there are various options which is "CHR" (Cloud Hosted Router) which is a VMimage meant for Virtualization only (seriously, I've tried to dd the image to a physical server and it just crashed as it does not contain any drivers for physical). One note as well if you are trying to do a baremetal install you may get an error "Error Loading Operating System" or........
  • ffmpeg how to concat and join two video clips


    This normally works but if not use my mencoder solution if the output video does not play past the joined time. the contents of list.txt need to look like this: file somefile.mp4 file somefile2.mp4 then run ffmpeg ffmpeg -f concat -i list.txt -c copy CME-2-router-dial-peer-final.mp4 The result is almost instant joining since there is no video processing since we are........
  • mencoder instead of ffmpeg to join or concatenate video files with different audio streams


    The problem for me is that Ihad two videos with different types of audio streams. ffmpeg would join them but they would not play past the point of the join. So Iused mencoder like below and it joined the audio and made them both mp3 streams and it worked! -oac mp3lame specifies the audio to be convered into an mp3 stream using the lame codec. after the oac the two files are the ones to be joined. the -o is the name of the outp........
  • dynagen / dynamips 100% high CPU usage solution - how to set the idlepc value


    The idlepc value is very important to dynamips and it is both image and often CPU dependent. There is no "magic"value that will work for all images and all CPUs so this is why I'll show you a quick and handy way. Also don't be disappointed, some values do not work well but idlepc gives you several. For example in my example below #6 didn't help at all but #7 got me down to about 6% CPU from 99-100%. *Befo........
  • How To Setup a Cisco CME (Cisco Manager Express) Virtual Router under Linux using dynamips and dynagen


    This tutorial will get your router up and running using emulation tools. In this case we'll be getting a Cisco C7206 (C7200 series) VXR router going which also supports SCCP VOIP services. dynamips is the emulator itself and dynagen is the front-end tool that helps us control everything. It is used by tools such as gns3 and eve-ng. Together the two tools (dynamips and dynagen) allow us to create and emulate REAL router........
  • Linux NIC connecting at 100M instead of 1000M gigabit speeds? It could be overheating


    I was using a small box as a router and one of the ports started going off and coming back at 100M. I truly believe it is simply that it was a case of overheating. Although CPUtemps were only about 67 degrees, the physical box itself was almost burning hot. Isolved the cooling issue and never had the issue again. Jul 28 15:09:27 swithbox kernel: e1000e: eth1 NIC Link is Up 1000 Mbps Full Duplex, Flow Control: Rx/Tx Jul 28 15:09:28 swithbox kernel:........
  • Cisco Unified Communications Manager Express Cheatsheet CUCME CME Tutorial Guide


    Video Links: How To Setup 2 Phones on a Single CME Router and get the GUI going. How to use Dialpeers with CME with two routers How to implement call restrictions using COR / Class of Restriction Getting started, let's enable ephones and DNs we can add a phone with........
  • Cisco Router Setup Guide and Tutorial Howto With Commands and Examples


    In most of the Cisco router IOS I find the ports like ge0/0 ge0/1 and ge0/2 or whatever your ports are down. They will not even give you a link light. So one of the first tasks should be getting the port you are working with up. In my case the first goal is often connectivity with the LAN and WAN. LAN = your local area network (eg. in the office/home ) WAN= your ISP/public internet (eg. fiber/cable/dsl/ethernet).........
  • Centos 6 / 7 / 8 How To Change Default nameservers in /etc/resolv.conf when using DHCP / dhclient


    First we need to create dhclient.conf if it doesn't exist or edit it: vi /etc/dhclient/dhclient.conf #add this line at the top add the IPs as commas they will be the highest priority nameservers and whatever your ISP gives you will be used after these one (good for DNS backup) prepend domain-name-servers 127.0.0.1,10.10.25.8; After you restart your network or run dhclient again you should see the contents of........
  • How Does Cisco CUCM (Cisco Unified Communication Manager) Work?


    Cisco's CUCM (Cisco Unified Communication Manager) is a system that combines voice, video, data and mobile products into a single unified management suite. At its core, the CUCMis like a "Super PBX" that controls the flow of all communications through an organization even single or multiple site deployments. Cisco's CUCMmakes communication more effective and simple through centralized management and unification of communications resources.........
  • named[1525]: error (broken trust chain) resolving 'min-api.cryptocompare.com/A/IN': 173.245.58.78#53 solution


    So you restarted your router/dhcpd server or for some other reason you wonder why DHCP is not working on any of your clients?You go and check that named is in fact running fine. But then you check /var/log/messages and see this error for everything hostname: named[1525]: error (broken trust chain) resolving 'min-api.cryptocompare.com/A/IN': 173.245.58.78#53 I've only ever seen this when the time on the server was off. It........
  • dhcpd.conf how to secure so only known and allowed clients will be given dhcpd IP address leases


    It's really simple and just a matter of the following line within the subnet declaration. deny unknown-clients; See example below: subnet 10.25.20.0 netmask 255.255.255.0 { range 10.25.20.11 10.25.20.254; deny unknown-clients; option routers 10.25.20.10; option domain-name-servers 208.67.222.222;  ........
  • Linux bash script to see what connected computers respond to ping


    A great way when moving your equipment to a new location, new router/switch etc to help confirm what MAC has what IP: for ip in `arp -na|awk '{print $2}'|sed s/(//g|sed s/)//g`; do echo ping $ip ping -c 1 -w 1 $ip > /dev/null if [ "$?" == 0 ]; then echo "$ip UP" fi done........
  • Linksys PAP2T No Dialtone and Cannot Hear Caller


    I have two lines on my PAP2T and the only thing that solved this problem rather instantly was to change the line with the problem to using port 5060 instead of 5061 (so both lines are using port 5600). Note that I am not forwarding either port in my router either. Some of the symptoms of this problem for me were the following: No dialtone or it would take several tries. You answer a call but the phone keeps ringing (takes a few times t........
  • Linux Debian/Ubuntu/Centos How To Force Internet Traffic Through PPTP L2TP OpenVPN Account Only


    The following assumes the computer is local/physical to you and/or it always has a LANIP so it can be accessed on site without having a default gateway. The key to this is not to set a default gateway for your computer or you can set a script on boot or other time to delete the gateway (where eth0 is the NIC you are using): route del default eth0 50.80.20.2 is the VPN server you connect to 192.168.1.1 is your........
  • Linux disable firmware prevents NIC/Ethernet from working phy0 -> rt2x00lib_request_firmware: Error - Failed to request Firmware.


    [ 17.208336] tg3 0000:08:00.0: eth0: Link is up at 1000 Mbps, full duplex [ 17.210194] tg3 0000:08:00.0: eth0: Flow control is on for TX and on for RX [ 76.000065] phy0 -> rt2x00lib_request_firmware: Error - Failed to request Firmware. [ 76.002332] ADDRCONF(NETDEV_CHANGE): eth0: link becomes ready [ 86.736004] eth0: no IPv6 routers present [ 148.960038] phy0 -> rt2x00lib_request_fi........
  • VPN Account Buyers Guide and General Info


    What matters most about VPNproviders in 2024? We are highly suspicious of VERYLARGE VPN providers that have LOW PRICES and HUGE DISCOUNTS. The suspicion is that for those who know what costs are involved to purchase thousands of IPs and servers are not small. At the prices that many of the big mainstream providers offer, it is likely unprofitable or barely profitable. Then, how are those companies making money or is that even the goal? There use........
  • Samsung Printer Password Login to change settings CLP


    First of all to find your IP you can hold the "X" button for a few seconds and it will print out the DHCP IP. Another way to find the IP that I prefer is to login to your router or switch and find a hostname that says something like "SEC001599CD2948" which will be your Samsung printer (at least for the C3xx or C4xx series of Samsung printers). The login and password for Samsung Syncthru Webservice:........
  • Asterisk VOIP Sipura/Linksys PAP2T Calls Not Being Received Solution


    This problem seemed to happen recently but was likely causing issues before where the phone(s) do not ring. Now there are a few reasons why this can happen especially if your adapter has DND mode enabled (disable it). However that wasn't my issue and Ionly figured it out the other day when by fluke if you're on the phone (making a call) then calls will come in. That's when Ifigured out the solution: This likely app........
  • Sipura / Linksys PAP/VOIP/SIP Adapter Issue Can't receiving incoming phone calls and you're behind a NAT router (99% of people)? solution


    Sipura / Linksys PAP/VOIP/SIP Adapter Issue Can't receiving incoming phone calls and you're behind a NAT router (99% of people)? 1. Login to the adapter. 2. Click on "Advanced" (location varies but usually somewhere on top) 2. Click on "SIP" 3. Scroll down to "NAT" (usually at the bottom). You'll find 2 columns with 4 rows of drop-down boxes (they'........
  • Setup PXE Boot using Centos and dhcpd, tftp and syslinux


    This is something I often setup for clients because it's very helpful for people in datacenters, this allows custom OS installs on demand, you can customize it more by using kickstart etc.. but here's a base I use before customizing more: This little script below will install everything you need to get booting by PXE Linux. It also assumes you set a local IP (be sure not to overwrite your existing IP) on eth0:0 (note the :0) as 192.168.1.10 and it........
  • LOG: MAIN PANIC failed to expand condition "${if eq {$authenticated_id}{}{0}{${if eq {$sender_address}{$local_part@$domain}{0}{${if match{$received_protocol}{N^e?smtps?a$N}{${perl{checkbx_autowhitelist}{$authenticated_id}}}{${if eq{$received_prot


    I experienced this with CPanel's Exim after an auto-update (a Google of this error produces lots of complaints with few clear solutions). In this case I'll put the solution at the top. Run /scripts/buildeximconf to rebuild the Exim config and it should be fine after that. mail -vs "from test" user@dest.com < .bash_history LOG: MAIN cwd=/root 4 args: send-mail -i -v user@dest.com LOG: MAIN &........
  • 95th Percentile Billing vs Usage Billing, what's better?


    There are all kinds of threads and links on the internet, and this seems to be a contentious issue butI don't know why. 95th percentile is either a good deal for some or a big rip off for others, Ijust said it there :) But the reality is that for MOST people who transfer low amounts of data but burst to higher speeds such as 40mbit+ even for short periods of time, then you'll pay a lot of money to do that. Basically 95th percentile is an-old archaic method........
  • Centos How To Add Static Network Route


    route add -net 192.16.5.0 netmask 255.255.255.0 eth0 Of course adjust as you need (eg. the 192.16.5.0 should be changed to the subnet you need access to and eth0 should be changed to the network device that you want that subnet routed through). I also use the /etc/sysconfig/rc.local script and add the above into it (remember that this route only gets added AFTER all other init scripts have finished though).........
  • rsync ERROR: sdb2/backup.r18 failed verification -- update retained.


    ERROR: sdb2/backup.r18 failed verification -- update retained. This happened when Iwas rsyncing a dying hard drive, a lot of people seem to report this as an error with rsync itself but I don't think rsync is the issue at all. I know the source hard drive was bad, it was having all kinds of timeout, seek, hardware ECC recovered and reset errors. The only time something else could be the problem is if the data is being corrupted in transit, perhaps through........
  • Telus + 2Wire 2700 Router Horrible


    Telus + 2Wire 2700 Router HorribleWell first of all let me say this is the only router/switch that sometimes seems to crash/disconnect computers on the local network. This device also thought it would be smart to block VOIP packets coming from my Sipura ATA VOIP adapters so I disabled the [quote:cb89ba7bff]"Invalid TCP Flag Attacks (NULL/XMAS/Other)"[/quote:cb89ba7bff] option Then all of a sudden I couldn't get onto any web pages, the wireless........
  • Vonage & Linksys Offer Trade-In Program


    Vonage & Linksys Offer Trade-In ProgramVonage & Linksys Offer Trade-In Program Monday, June 13 @ 09:22:36 PDT Vonage is offering customers a way to get a free 802.11g router when they turn in their old one. advertising For a limited time, customers can trade-in their used router any brand, any model for a Linksys Wireless-G Router with 2 Phone Jacks for broadband telephony (WRTP54G) for free (after rebates), when they si........
  • It's not all about the speed.


    It's not all about the speed.I'd also thought I'd mention that speed is not everything. Routing is the key, because if one router you hit is slow then it doesn't matter how fast your connection is. I have found that locally, Telus has much better routing than Shaw (although I have not yet tested their new DOCSIS network). There are also some countries such as Sweden that offer high speed connections, but the high speed only applies locally. The reason is that man........
  • Wireless/xmit power - DD-WRT v23 SP2 (09/15/06) std - build 3932 Linksys WRT54G/GL/GS


    I played around with xmit power (how much power in mW) to see if I could increase the range and signal strength. Idon't think this Linksys WRT54G's strength is the wireless, it seems to have poor signal quality and transfer rates all around. Ithink part of the problem is also that there are several wireless networks around my house that could be interfering and the walls are thick here. Anyaway, moving on now :) The default is 28mW and I increased it to........
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