Posts for: #Linux

Networking Concepts in RHEL

#allposts  #linux  #networking  #in_progress  
user01@rhel10-vm5:~$ cat /etc/protocols
# /etc/protocols:
# $Id: protocols,v 1.12 2016/07/08 12:27 ovasik Exp $
#
# Internet (IP) protocols
#
#   from: @(#)protocols 5.1 (Berkeley) 4/17/89
#
# Updated for NetBSD based on RFC 1340, Assigned Numbers (July 1992).
# Last IANA update included dated 2011-05-03
#
# See also http://www.iana.org/assignments/protocol-numbers

ip  0   IP      # internet protocol, pseudo protocol number
hopopt  0   HOPOPT      # hop-by-hop options for ipv6
icmp    1   ICMP        # internet control message protocol
igmp    2   IGMP        # internet group management protocol
ggp 3   GGP     # gateway-gateway protocol
ipv4    4   IPv4        # IPv4 encapsulation
st  5   ST      # ST datagram mode
tcp 6   TCP     # transmission control protocol
cbt 7   CBT     # CBT, Tony Ballardie <[email protected]>
egp 8   EGP     # exterior gateway protocol
igp 9   IGP     # any private interior gateway (Cisco: for IGRP)
bbn-rcc 10  BBN-RCC-MON     # BBN RCC Monitoring
nvp 11  NVP-II      # Network Voice Protocol
pup 12  PUP     # PARC universal packet protocol
argus   13  ARGUS       # ARGUS (deprecated)

<---- output omitted ---->

user01@rhel10-vm5:~$ ip add show 
1: lo: <LOOPBACK,UP,LOWER_UP> mtu 65536 qdisc noqueue state UNKNOWN group default qlen 1000
    link/loopback 00:00:00:00:00:00 brd 00:00:00:00:00:00
    inet 127.0.0.1/8 scope host lo
       valid_lft forever preferred_lft forever
    inet6 ::1/128 scope host noprefixroute 
       valid_lft forever preferred_lft forever
2: enp0s3: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc fq_codel state UP group default qlen 1000
    link/ether 08:00:27:41:01:e5 brd ff:ff:ff:ff:ff:ff
    altname enx0800274101e5
    inet 192.168.56.103/24 brd 192.168.56.255 scope global dynamic noprefixroute enp0s3
       valid_lft 437sec preferred_lft 437sec
    inet6 fe80::a00:27ff:fe41:1e5/64 scope link noprefixroute 
       valid_lft forever preferred_lft forever
user01@rhel10-vm5:~$

NetworkManager.service is the Linux unit that runs the daemon responsible for networking on RHEL. One of the tools to interact with NetworkManager is nmcli.

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SSH

#allposts  #networking  #linux  #in_progress 

SSH on Cisco devices

SSH Terminal-Line Access Feature

replaces reverse Telnet feature that was typically configured on terminal services routers.

provides secure console access for servers physically connected to a terminal services router.

introduces the concept of ‘rotary’.

Remember that each physical Async port has an associated logical line to it.

Each router line (not the Async ports) must be configured with a unique rotary number.

Number of rotaries == number of lines

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