The services running alongside routing that keep a network usable. Articles tagged IP Services cover NAT, DHCP, NTP, SNMP, syslog, NetFlow and IP SLA on Cisco IOS XE.
The NAT config looks correct and nothing is translating. One command splits the problem in two: no entry means the traffic never matched, an entry means the failure is downstream. Captured on IOS XE 17.18.2 in CML, where a single missing ip nat inside leaves the table empty at 0 hits.
Harden a Cisco router by disabling unused services, proven with a real before-and-after Nmap scan taking Telnet from open to closed, plus syslog design.
Configure authenticated NTP on Cisco IOS XE, why IOS flags MD5 as weak, and how ntp authenticate and trusted-key stop a rogue server moving your clock.
Services break in ways that routing never does. A route either exists or it does not; a NAT translation either
IPv6 does several things differently from IPv4, and a few of them are genuinely better - once you understand them. Prefix
You are troubleshooting a problem that only the packets can explain - a malformed handshake, an unexpected retransmission, a mystery drop.
SNMPv1 and v2c send everything - including your community string, which is effectively a password - in cleartext across the network. Anyone
Most people configure an IOS DHCP server once, with three lines - network, default-router, dns-server - and never touch it
Two customers connect to your router. Both, entirely by coincidence, use 10.5.5.0/24 internally. Both have a
There is a particular kind of fear that stops engineers from using the most powerful troubleshooting tool on a Cisco
Most networks need to agree on what time it is to within a second or so, and NTP has done
IPv6 host addressing is where a lot of otherwise competent engineers quietly lose confidence, because there are three mechanisms that