[conspire] desktop and my laptop can't ping one to another

[Ruben Safir]

On Wed, Jul 29, 2020 at 08:07:51AM -0700, Michael Paoli wrote:
> So, what about the ARP table and /etc/ethers - if that's present?
> What are the Ethernet MAC addresses associated with each IP
> in question, and are each making it into the ARP table of
> the other - if they're on same subnet ... (or in /etc/ethers).
> What does the routing, subnets, masks, etc. for each look like?
> And gateways/routers?


IMO your making this two complicated without reason.  He doesn't need
top confirm the arp tables, and the ethernet mac addresses.  This is not
a demonstration of networking principles for a networking class.

He has two machines and he just needs to see if they can ping each
other, and there is a wifi gateway in between.


> What about sniffing of traffic, most notably relevant ARP
> related traffic and ICMP traffic - what does that
> show?  Is traffic making it in/out the correct interfaces
> and to correct target(s)?  What about firewall(s) on
> host(s) and/or along the way?
> 
> What else can/can't these hosts get to - and especially
> on the same subnet?  What else can/can't they ping?
> 
> $ dig -x 75.75.75.75 +short
> cdns01.comcast.net.
> $ dig -x 75.75.76.76 +short
> cdns02.comcast.net.
> $
> 
> This looks likely to be some home/office Comcast ISP setup.
> What's between the hosts?  Is it some Comcast
> home/business "router"(/firewall/NAT/SNAt/...) device?
> Is it firewalling the hosts from each other?
> If the hosts are on same subnet, what if one connects them direct
> with a crossover cable, or via just a switch with no firewall on it?
> 
> >From: "Rick Moen" <rick at linuxmafia.com>
> >Subject: [conspire] (forw) Re:  Federales in Portland?
> >Date: Tue, 28 Jul 2020 13:57:57 -0700
> 
> >I'm assuming Denny meant to send this request for help to the public
> >forum, rather than to me privately.
> >
> >----- Forwarded message from Denny Yang <yangcdenny at gmail.com> -----
> >
> >Date: Tue, 28 Jul 2020 13:34:43 -0700
> >From: Denny Yang <yangcdenny at gmail.com>
> >To: Rick Moen <rick at linuxmafia.com>
> >Subject: Re: [conspire] Federales in Portland?
> >
> > Hi Rick,
> >
> >I hope this email finds you well.
> >
> >Right now my desktop and my laptop can't ping one to another.
> >
> >Here are the settings that I have so far for each machine.  The desktop is
> >connected to the router, and the laptop is using WIFI.
> >
> >*DESKTOP:*
> >
> >*#ip addr show *
> >$enp2s0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc fq_codel state UP
> >group default qlen 1000
> >    link/ether 8c:ec:4b:45:35:4c brd ff:ff:ff:ff:ff:ff
> >    inet 192.168.1.2/24 brd 192.168.1.255 scope global dynamic
> >noprefixroute enp2s0
> >
> >#systemctl status NetworkManager.service = active/running, no error messages
> >
> >*#netstat -rn*
> >Kernel IP routing table
> >Destination     Gateway         Genmask         Flags   MSS Window  irtt
> >Iface
> >0.0.0.0         192.168.1.1     0.0.0.0         UG        0 0          0
> >enp2s0
> >172.17.0.0      0.0.0.0         255.255.0.0     U         0 0          0
> >docker0
> >192.168.1.0     0.0.0.0         255.255.255.0   U         0 0          0
> >enp2s0
> >192.168.122.0   0.0.0.0         255.255.255.0   U         0 0          0
> >virbr0
> >
> >*#/etc/resolv.conf*
> ># Generated by NetworkManager
> >nameserver 192.168.1.1
> >
> >*# firewall-cmd --zone=public --list-services*
> >cockpit dhcpv6-client ftp ssh
> >
> >*# firewall-cmd --zone=public --list-ports*
> >514/tcp
> >
> >*LAPTOP: *
> >
> >*ip addr show*
> >wlp1s0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc noqueue state UP
> >group default qlen 1000
> >    link/ether 7c:67:a2:13:3c:a1 brd ff:ff:ff:ff:ff:ff
> >    inet 10.232.185.182/14 brd 10.235.255.255 scope global dynamic
> >noprefixroute wlp1s0
> >
> >#systemctl status NetworkManager.service = active/running, no error messages
> >
> >*# netstat -rn*
> >Kernel IP routing table
> >Destination     Gateway         Genmask         Flags   MSS Window  irtt
> >Iface
> >0.0.0.0         10.232.0.1      0.0.0.0         UG        0 0          0
> >wlp1s0
> >10.232.0.0      0.0.0.0         255.252.0.0     U         0 0          0
> >wlp1s0
> >172.17.0.0      0.0.0.0         255.255.0.0     U         0 0          0
> >docker0
> >192.168.122.0   0.0.0.0         255.255.255.0   U         0 0          0
> >virbr0
> >
> >*#/etc/resolv.conf*
> >Generated by NetworkManager
> >nameserver 75.75.75.75
> >nameserver 75.75.76.76
> >nameserver 2001:558:feed::1
> ># NOTE: the libc resolver may not support more than 3 nameservers.
> ># The nameservers listed below may not be recognized.
> >nameserver 2001:558:feed::2
> >
> >*# firewall-cmd --zone=public --list-services*
> >cockpit dhcpv6-client ftp ssh
> >
> >*# firewall-cmd --zone=public --list-ports*
> >515/tcp 514/tcp
> >
> >Again, I apologize for this lengthy email.  It's driving me nuts now why
> >these two machines can't communicate with each other.
> >I have a feeling that this has to do with the laptop IP 10.net.  But still
> >don't know where the problem is.
> 
> 
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