Author Archives: alex

Cisco ASR-1001-X Update

There are at least two pieces of software you can update in a Cisco ASR-1001-X. The ROMMON (firmware) and the IOS itself. This router uses “Cisco IOS XE Software”. Which is an IOS process on a Linux kernel as far … Continue reading

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DHCP Relay on Linux

DHCP relaying is used to forward DHCP requests to a DHCP server if the client and the server are not on the same network. One standard implementation of this is isc-dhcp-relay which is part of the isc-dhcp package. Problem: The … Continue reading

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LS Style After Devuan 3 or Debian 10 Update

After Devuan 3 update ls output showed characters, that are not really in the directory listing. The reason is that “ls” draws quotes around filenames with spaces. This is a bug from my point of view, ls should never change … Continue reading

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Time Format after Devuan 3 and Debian 10 Update

After updating to Devuan 3 the date command shows 12hours am/pm but my days have 24 hours. The locale was always en_US.UTF8 to keep sane command and error output. Debian 10 thinks they had to fix the correct hour display … Continue reading

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Mikrotik OSPF Routing Distance Ignored

Discussion: Every routing protocol has a default distance to help the router to decide which route to use in case of multiple routes for the same destination. For Mikrotik routers these distances are listed here:https://wiki.mikrotik.com/wiki/Manual:Route_Selection_Algorithm_in_RouterOSIf you want to configure a … Continue reading

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ARP and Broadcast Packets Missing

Problem: A Linux box with Debian 9 (kernel 4.9) on a HP server with Intel i40e (X710) network cards, is not reachable from neighbor machines, because ARP does not work. Discussion: while testing with tcpdump ARP worked, but later ARP … Continue reading

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MITMProxy and IOS 13

Problem: if you want to debug a IOS app with MITMProxy, the iPhone needs to trust the MITMProxy CA. This is done by going to http://mitm.it/ and clicking on the apple symbol. Then you have to accept the “profile” in … Continue reading

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Linux Live-boot Fails after Debian/Devuan Update

Problem: after updating from Debian 8 to Devuan 2 the overlay live-boot failes with “no such device” Discussion: I use a bootable USB stick combined with live-boot. In this case the USB stick partition 3 is a normal ext4 file … Continue reading

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Greenlock(-express) Letsencrypt Fails with ECONNRESET

Problem: after upgrading vom greenlock-express v2.0 to v2.5 and switching from acme-v1 to acme-v2 every attempt to register a new TLS cert with Letsencrypt fails with “ECONNRESET” Discussion: the new version of greenlock tries to validate the .well-known/acme-challenge file before … Continue reading

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Apache Start Hangs during Reboot of a KVM Virtual Server

Problem: Apache needs very long to start on a virtual server running on a KVM/QEMU virtual maschine. Solution: Apache needs a RNG (random number generator) for startup, probably because of TLS. A pure virtual maschine has no RNG device per … Continue reading

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