Networking

When I moved in Luxembourg, I subscribed to Tango Luxembourg Fiber internet access. Back then, I got the usual dynamic public IP address “for free”. It was changing every 36 hours but at least it was a public one. Recently, I changed my subscription to the 1 gigabit/s offer and soon after, I realized my VPNs and 6to4 tunnel was not working anymore. After a brief troubleshooting session, I found out I was receiving a private IP address instead of the usual public 94....

After reading many articles and trying many things, this is how I solved it. For docker daemon itself to use a proxy, configure environment variables using systemd file /etc/systemd/system/docker.service.d/http-proxy.conf : [Service] Environment="HTTP_PROXY=http://user:pass@proxy.domain.com:3128/" Environment="HTTPS_PROXY=http://user:pass@proxy.domain.com:3128/" Environment="NO_PROXY=localhost,docker,*.domain.com" For gitlab-runner daemon itself to use a proxy, configure environment variables using systemd file /etc/systemd/system/gitlab-runner.service.d/http-proxy.conf : [Service] Environment="HTTP_PROXY=http://user:pass@proxy.domain.com:3128/" Environment="HTTPS_PROXY=http://user:pass@proxy.domain.com:3128/" Environment="NO_PROXY=localhost,docker,*.domain.com" Reload systemd and restart docker daemon: systemctl daemon-reload systemctl restart docker For git commands run by gitlab-runner to use a proxy, use gitlab-runner config file....

Here is how to establish an IPsec tunnel between an Ubuntu 20.04 host and a Mikrotik router using IKEv2. The 2 endpoints of the tunnel are: ubuntu.xentoo.info : the Ubuntu server. This server has a local private subnet 10.0.0.0/24 and a fixed public IPv4 address 1.2.3.4 . The hostname ubuntu.xentoo.info resolves to the public IP address. mikrotik.xentoo.info : the Mikrotik router. This router has a local private subnet 192.168.0.0/24 and a dynamic public IPv4 address....

Hi guys, I moved to Luxembourg and I have opted for Tango Fiber. Their router is a Fritz!box which I do not like at all. I have a spare Mikrotik router, so here is how to configure. Tango Fiber uses PPPoE over VLAN 35, MTU is 1480. You need to ask the PPP credentials via a contact form on the website, they will answer within a few days. I have decided to use ether1 to connect the Fiber and create a VLAN interface named ether1....

For easier use with Cacti, it is easier to group statistics per type instead of per CPU. So you would have a parent OID for CPU time spent by user with many values (one per CPU). Put the following in /etc/snmp/percpudetail: #!/bin/bash case "$1" in "user") grep ^cpu /proc/stat | awk '{print 2}' ;; "nice") grep ^cpu /proc/stat | awk '{print 3}' ;; "system") grep ^cpu /proc/stat | awk '{print 4}' ;; "idle") grep ^cpu /proc/stat | awk '{print 5}' ;; "iowait") grep ^cpu /proc/stat | awk '{print 6}' ;; "irq") grep ^cpu /proc/stat | awk '{print 7}' ;; "softirq") grep ^cpu /proc/stat | awk '{print 8}' ;; esac Make it executable:...

I needed to export detailed CPU statistics from Linux servers using SNMP. While UCD-SNMP-MIB export some detailed stats, it only does it for the whole system. I may have missed something easier though :-) So here is a BASH script, put it in /etc/snmp/percpustats: #!/bin/bash /bin/grep "^$1 " /proc/stat | sed -e 's/^cpu[0-9]* *//' | tr ' ' '\n' Make it executable: chmod +x /etc/snmp/percpustats This simple script takes a single argument, which is the cpu id you want to look at....

So you have your Unified Networking Lab (UNL) server running and you want to use arbitrary QEMU images with it. Here is how to create one. All UNL data is stored under /opt/unetlab , images are stored under /opt/unetlab/addons and QEMU images are a folder deeper under /opt/unetlab/addons/qemu . UNL expects to find images within directories named according to some scheme. The directory names must start with some keywords followed by anything you want....

If you get the following message on your Cisco router when you connect a VPN client using PPTP *Mar 17 16:43:02.371: Vi5 PPP: Control packet rate limit 10 reached *Mar 17 16:43:02.371: Vi5 PPP: Entering block state for 30 seconds *Mar 17 16:43:02.371: Vi5 PPP: Packet throttled, Dropping packet Then it means you have an IOS version which greatly reduced the allowed rate of PPP control packets before it triggers a block....

I was recently confronted to a strange issue with a PPTP VPN connection to a central site. Some users could connect and some others could not. They all used Windows 7 with SP1, configured the same way, and all computers were behind NAT/PAT routers but not necessarily on the same site. On the VPN server, the only information I could get was this log stating the GRE protocol was unreachable:...

GNS3 Sourceforge account provides an OVA image ready to run gns3-server for those who want to use Cisco IOS on Unix images . However, at the time of this writing, the gns3-server version is outdated (1.3.3). The client must have the same version as the server to be able to connect to it. Here is how you can update the gns3-server inside the image. Note that you need Internet access for the update....