ip – Two routers connected to the same router and only one can ping another

There are two routers connected together to Arris TG3442 router:

  • TP-Link Archer C2 AC750 (uses 192.168.1.X addressing)
  • D-Link DIR-853 (uses 192.168.2.X addressing)

When I use any device in 192.168.1.X network: I can ping any device in 192.168.2.X network including router itself (which sits under 192.168.2.1).

enter image description here

When I do the same opposite then it turns out that any device in 192.168.2.X network can ping any device in 192.168.1.X except router. Any ping to 192.168.1.1 results in connection timeout

enter image description here

enter image description here

My assumptions:

  • The situation is correct, no error or problem here
  • The 192.168.1.1 router is most likely configured to reject ping
  • But it allows ping to pass through to any device
  • The 192.168.2.1 router is configured to respond to ping and pass it through.

Do I understand this situation correctly?

Openstack Instances cant communicate or ping the subnet the controller and compute is on

For some reason i am not able to ping from an instance to the subnet the controller and compute’s are on. The network is pretty simple.

VM’s/Instances: 10.10.2.0/24
Controller/Compute’s: 10.10.1.0/24
The routers external gateway is 10.10.1.4 which I can ping from the instances. Ant help would be greatly appreciated.

linux – Unable to ping between PCs in the same network but different subnets

Stack Exchange Network


Stack Exchange network consists of 176 Q&A communities including Stack Overflow, the largest, most trusted online community for developers to learn, share their knowledge, and build their careers.

Visit Stack Exchange

networking – failed to ping a guest VM on virtualbox from another Linux machine

to put it simple, here are two machines in my local intranet.

One is Ubuntu based Pop!-OS computer, the other is a Windows 10 DELL desktop. Both computers are wirelessly connected to a local home network.

Now on my Windows 10 destop I installed virtualbox 6.0.1, on which I installed ubuntu based Linux distro, Kali.

For my own reason i need to set a static IP for the Kali VM, basically I followed this article for the setup. To recap, here are the specs:

  1. from the host network manager of Virtual box, the ipv4 setting is:
    192.168.56.1, DHCP disabled.
  2. For the network setting for Kali, on adapter 1 tab, the network mode
    is: NAT, on adapter2 tab, attached to host-only network configured in
    step1.

On the Kali VM, the file /etc/network/interfaces:

#The host-only network interface
auto eth1
iface eth1 inet static
address 192.168.56.101
netmask 255.255.255.0
network 192.168.56.1
broadcast 192.168.56.255

This setting was effective and verified through the command “ifconfig”

here is what I observed:

From the virtual box host (Windows 10), I can ping the guest OS (Kali):

ping 192.168.56.101

However I can’t do the same from my other computer (pop!-OS), when I ping Kali using the above same command, it returned:

(base) jon@pop-os:~$ ping 192.168.56.101
PING 192.168.56.101 (192.168.56.101) 56(84) bytes of data.
From 67.59.236.253 icmp_seq=1 Packet filtered

Here are a few notes worthy mentioning:

  • The gateway of the local network is: 192.168.86.1 ( I don’t know why
    the default host network on virtualbox was set to 192.168.56.1, does
    it make the virtual box and its VMs a subnet?)
  • I switch the network mode on Kali from NAT to bridged, it remained
    the same: I can’t ping from a separate computer other than the host
    DELL desktop (Window 10).
  • I don’t know where the ip 67.59.236.253 came from. It’s not the ip
    that my ISP provider assigned to me.

My goal is to be able to connect to Kali from any computer in my intranet therefore I can use its services such as database server.

Anyone please help me make things right?

network – Can Ping Google DNS from Firewall, but not from VM behind Firewall

I have the following network setup https://i.ibb.co/wwPLH2H/Network.png

All traffic from 10.0.64.0 / 27 behind FirewallB (firewallsm) reaches 192.168.28.0 / 27 network via the LAN interface of FirewallA (firewallwm), and the same traffic also reaches internet in the same way, as follows:

10.0.64.42 (VM) > FirewallB (LAN) > FirewallA (LAN) > FirewallA (WAN) > Laptop’s Wireless NIC > Wifi Router

Strangely FirewallB (firewallsm) can ping Google DNS but the VM 10.0.64.42 for some reason cannot ping Google DNS. I have set all protocols, ports as allowed on FirewallB (firewallsm) to reach FirewallA (firewallwm).

FirewallA (firewallwm)

Gateway – https://i.ibb.co/bRC8P8G/Firewall-A-GW.png

LAN Interface Rule – https://i.ibb.co/XWSnLRd/Firewall-A-1-dell-Rule.png

WAN Interface Rule – https://i.ibb.co/zZwcnjJ/Firewall-A-2-WAN-Rule.png

FirewallA (firewallsm) logs show 10.0.64.42 traffic is allowed through its WAN

Log – https://i.ibb.co/9cqPSW7/Firewall-A-Packet-log.png

Log – https://i.ibb.co/kVTX31B/Firewall-A-Packet-log-2.png

FirewallB (firewallsm)

Gateway – https://i.ibb.co/pPQC1p8/Firewall-B-GW.png

LAN Rule – https://i.ibb.co/VY9vFVL/Firewall-B-1-dell-Rule.png

tcpdump for 10.0.64.42 VM on FirewallB LAN (em0)

root@firewallsm:~ # tcpdump -i vmx0 host 10.0.64.42 and host 8.8.8.8 and icmp
tcpdump: verbose output suppressed, use -v or -vv for full protocol decode
listening on vmx0, link-type EN10MB (Ethernet), capture size 262144 bytes
06:17:09.324409 IP 10.0.64.42 > dns.google: ICMP echo request, id 1, seq 1, length 40
06:17:13.853917 IP 10.0.64.42 > dns.google: ICMP echo request, id 1, seq 2, length 40
06:17:18.858484 IP 10.0.64.42 > dns.google: ICMP echo request, id 1, seq 3, length 40

tcpdump for 10.0.64.42 VM on FirewallA LAN (em0)

root@firewallwm:~ # tcpdump -i em0 host 8.8.8.8 and icmp -n
tcpdump: verbose output suppressed, use -v or -vv for full protocol decode
listening on em0, link-type EN10MB (Ethernet), capture size 262144 bytes
06:17:09.335331 IP 10.0.64.42 > 8.8.8.8: ICMP echo request, id 1, seq 1, length 40
06:17:13.865408 IP 10.0.64.42 > 8.8.8.8: ICMP echo request, id 1, seq 2, length 40
06:17:23.870819 IP 10.0.64.42 > 8.8.8.8: ICMP echo request, id 1, seq 4, length 40

tcpdump for 10.0.64.42 VM on FirewallA WAN (em1)

root@firewallwm:~ # tcpdump -i em1 host 8.8.8.8 and icmp -n
tcpdump: verbose output suppressed, use -v or -vv for full protocol decode
listening on em1, link-type EN10MB (Ethernet), capture size 262144 bytes

Ping from FirewallB successful in pinging Google DNS

root@firewallsm:~ # ping 8.8.8.8
PING 8.8.8.8 (8.8.8.8): 56 data bytes
64 bytes from 8.8.8.8: icmp_seq=0 ttl=127 time=13.196 ms
64 bytes from 8.8.8.8: icmp_seq=1 ttl=127 time=12.625 ms
64 bytes from 8.8.8.8: icmp_seq=2 ttl=127 time=12.609 ms
^C
--- 8.8.8.8 ping statistics ---
16 packets transmitted, 16 packets received, 0.0% packet loss
round-trip min/avg/max/stddev = 11.705/13.026/15.910/1.111 ms

tcpdump of FirewallA LAN (em0)

root@firewallwm:~ # tcpdump -i em0 host 8.8.8.8 and icmp -n
tcpdump: verbose output suppressed, use -v or -vv for full protocol decode
listening on em0, link-type EN10MB (Ethernet), capture size 262144 bytes
06:22:21.816908 IP 192.168.10.7 > 8.8.8.8: ICMP echo request, id 23594, seq 0, length 64
06:22:21.827095 IP 8.8.8.8 > 192.168.10.7: ICMP echo reply, id 23594, seq 0, length 64
06:22:22.876598 IP 192.168.10.7 > 8.8.8.8: ICMP echo request, id 23594, seq 1, length 64
06:22:22.886317 IP 8.8.8.8 > 192.168.10.7: ICMP echo reply, id 23594, seq 1, length 64
06:22:23.948947 IP 192.168.10.7 > 8.8.8.8: ICMP echo request, id 23594, seq 2, length 64
06:22:23.957978 IP 8.8.8.8 > 192.168.10.7: ICMP echo reply, id 23594, seq 2, length 64

tcpdump of FirewallA WAN (em1)

root@firewallwm:~ # tcpdump -i em1 host 8.8.8.8 and icmp -n
tcpdump: verbose output suppressed, use -v or -vv for full protocol decode
listening on em1, link-type EN10MB (Ethernet), capture size 262144 bytes
06:22:21.817029 IP 192.168.47.132 > 8.8.8.8: ICMP echo request, id 24689, seq 0, length 64
06:22:21.826993 IP 8.8.8.8 > 192.168.47.132: ICMP echo reply, id 24689, seq 0, length 64
06:22:22.876700 IP 192.168.47.132 > 8.8.8.8: ICMP echo request, id 24689, seq 1, length 64
06:22:22.886219 IP 8.8.8.8 > 192.168.47.132: ICMP echo reply, id 24689, seq 1, length 64
06:22:23.949057 IP 192.168.47.132 > 8.8.8.8: ICMP echo request, id 24689, seq 2, length 64
06:22:23.957845 IP 8.8.8.8 > 192.168.47.132: ICMP echo reply, id 24689, seq 2, length 64

networking – Cannot use apt on WSL2 but ping works

I’m trying to use a WSL2 installation of Ubuntu.

apt-get does not work. For example if I want to install net-tools I obtain

daniele@IOS-PC:~$ sudo apt-get install net-tools
Reading package lists... Done
Building dependency tree
Reading state information... Done
The following NEW packages will be installed:
  net-tools
0 upgraded, 1 newly installed, 0 to remove and 0 not upgraded.
Need to get 196 kB of archives.
After this operation, 864 kB of additional disk space will be used.
Err:1 http://archive.ubuntu.com/ubuntu focal/main amd64 net-tools amd64 1.60+git20180626.aebd88e-1ubuntu1
  Could not connect to archive.ubuntu.com:80 (91.189.88.142), connection timed out Could not connect to archive.ubuntu.com:80 (91.189.88.152), connection timed out
E: Failed to fetch http://archive.ubuntu.com/ubuntu/pool/main/n/net-tools/net-tools_1.60+git20180626.aebd88e-1ubuntu1_amd64.deb  Could not connect to archive.ubuntu.com:80 (91.189.88.142), connection timed out Could not connect to archive.ubuntu.com:80 (91.189.88.152), connection timed out
E: Unable to fetch some archives, maybe run apt-get update or try with --fix-missing?

The strange thing is that I’m able to ping both the IP address and the name of the server:

daniele@IOS-PC:~$ ping 91.189.88.152
PING 91.189.88.152 (91.189.88.152) 56(84) bytes of data.
64 bytes from 91.189.88.152: icmp_seq=1 ttl=52 time=50.0 ms
64 bytes from 91.189.88.152: icmp_seq=2 ttl=52 time=50.5 ms
64 bytes from 91.189.88.152: icmp_seq=3 ttl=52 time=51.1 ms
64 bytes from 91.189.88.152: icmp_seq=4 ttl=52 time=50.7 ms
^C
--- 91.189.88.152 ping statistics ---
4 packets transmitted, 4 received, 0% packet loss, time 3004ms
rtt min/avg/max/mdev = 50.006/50.578/51.086/0.386 ms
daniele@IOS-PC:~$ ping archive.ubuntu.com
PING archive.ubuntu.com (91.189.88.142) 56(84) bytes of data.
64 bytes from aerodent.canonical.com (91.189.88.142): icmp_seq=1 ttl=52 time=53.4 ms
64 bytes from aerodent.canonical.com (91.189.88.142): icmp_seq=2 ttl=52 time=51.0 ms
64 bytes from aerodent.canonical.com (91.189.88.142): icmp_seq=3 ttl=52 time=50.8 ms
64 bytes from aerodent.canonical.com (91.189.88.142): icmp_seq=4 ttl=52 time=51.4 ms
64 bytes from aerodent.canonical.com (91.189.88.142): icmp_seq=5 ttl=52 time=50.0 ms
64 bytes from aerodent.canonical.com (91.189.88.142): icmp_seq=6 ttl=52 time=50.2 ms
^C
--- archive.ubuntu.com ping statistics ---
6 packets transmitted, 6 received, 0% packet loss, time 5008ms
rtt min/avg/max/mdev = 49.958/51.127/53.421/1.135 ms

How can I use the apt-get command correctly?

ubuntu – ping: example.org: No address associated with hostname

I am facing a problem I cannot explain:

If I do

ping example.org

I am getting the result

ping: example.org: No address associated with hostname

dig returns an empty result:

dig example.org

; <<>> DiG 9.16.1-Ubuntu <<>> example.org
;; global options: +cmd
;; Got answer:
;; ->>HEADER<<- opcode: QUERY, status: NXDOMAIN, id: 11024
;; flags: qr rd ra; QUERY: 1, ANSWER: 0, AUTHORITY: 0, ADDITIONAL: 1

;; OPT PSEUDOSECTION:
; EDNS: version: 0, flags:; udp: 65494
;; QUESTION SECTION:
; example.org.  IN  A

;; Query time: 20 msec
;; SERVER: 127.0.0.53#53(127.0.0.53)
;; WHEN: Sun Feb 28 18:27:28 UTC 2021
;; MSG SIZE  rcvd: 52

If I ping google, the ping get’s a pong. Well – as I am using the built-in resolver:

# See man:systemd-resolved.service(8) for details about the supported modes of
# operation for /etc/resolv.conf.

nameserver 127.0.0.53
options edns0 trust-ad

I thought about checking it’s stats

systemd-resolve --statistics

and flush the cache:

systemd-resolve --flush-caches

But still the domain can not be resolved.

If I add google’s 8.8.4.4 to resolv.conf, the domain can be resolved. But I don’t want to use an external resolver. What did I miss in this case?

network – why ping registry-1.docker.io returns Request timeout for icmp_seq even when I can nslookup or dig?

I used google and cloudflare and can dig with both set as DNS server on my mac.

$ dig registry-1.docker.io

; <<>> DiG 9.10.6 <<>> registry-1.docker.io
;; global options: +cmd
;; Got answer:
;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 16322
;; flags: qr rd ra; QUERY: 1, ANSWER: 8, AUTHORITY: 0, ADDITIONAL: 1

;; OPT PSEUDOSECTION:
; EDNS: version: 0, flags:; udp: 512
;; QUESTION SECTION:
;registry-1.docker.io.      IN  A

;; ANSWER SECTION:
registry-1.docker.io.   5   IN  A   107.23.149.57
registry-1.docker.io.   5   IN  A   34.195.246.183
registry-1.docker.io.   5   IN  A   23.22.155.84
registry-1.docker.io.   5   IN  A   34.238.187.50
registry-1.docker.io.   5   IN  A   52.1.121.53
registry-1.docker.io.   5   IN  A   52.5.11.128
registry-1.docker.io.   5   IN  A   18.213.137.78
registry-1.docker.io.   5   IN  A   54.236.165.68

;; Query time: 62 msec
;; SERVER: 8.8.8.8#53(8.8.8.8)
;; WHEN: Sat Feb 20 23:32:34 GMT 2021
;; MSG SIZE  rcvd: 177

worked with cloudlfare too

$ dig registry-1.docker.io

; <<>> DiG 9.10.6 <<>> registry-1.docker.io
;; global options: +cmd
;; Got answer:
;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 64168
;; flags: qr rd ra; QUERY: 1, ANSWER: 8, AUTHORITY: 0, ADDITIONAL: 1

;; OPT PSEUDOSECTION:
; EDNS: version: 0, flags:; udp: 1232
;; QUESTION SECTION:
;registry-1.docker.io.      IN  A

;; ANSWER SECTION:
registry-1.docker.io.   29  IN  A   54.236.165.68
registry-1.docker.io.   29  IN  A   52.1.121.53
registry-1.docker.io.   29  IN  A   54.85.56.253
registry-1.docker.io.   29  IN  A   34.238.187.50
registry-1.docker.io.   29  IN  A   34.195.246.183
registry-1.docker.io.   29  IN  A   54.236.131.166
registry-1.docker.io.   29  IN  A   18.232.227.119
registry-1.docker.io.   29  IN  A   52.54.232.21

;; Query time: 60 msec
;; SERVER: 1.1.1.1#53(1.1.1.1)
;; WHEN: Sat Feb 20 23:30:34 GMT 2021
;; MSG SIZE  rcvd: 177

using nslookup too gives result:
$ nslookup registry-1.docker.io
Server: 8.8.8.8
Address: 8.8.8.8#53

Non-authoritative answer:
Name: registry-1.docker.io
Address: 54.236.165.68
Name: registry-1.docker.io
Address: 54.85.56.253
Name: registry-1.docker.io
Address: 3.211.199.249
Name: registry-1.docker.io
Address: 34.195.246.183
Name: registry-1.docker.io
Address: 52.55.168.20
Name: registry-1.docker.io
Address: 34.238.187.50
Name: registry-1.docker.io
Address: 18.232.227.119
Name: registry-1.docker.io
Address: 54.236.131.166

but when I try to ping this is what I am getting:

$ ping registry-1.docker.io     
PING registry-1.docker.io (54.236.165.68): 56 data bytes
Request timeout for icmp_seq 0
Request timeout for icmp_seq 1
Request timeout for icmp_seq 2
Request timeout for icmp_seq 3
Request timeout for icmp_seq 4

I was trying to build a pod when I discovered this issue ! and I am getting ImagePullBackOff while trying

kubectl run redis --image=redis:alpine

ping – ICMP-IPv4 total length exceeds packet length

I have a problem with +500byte ICMP packet, I am using ubuntu 16.04 and firewall inactive. When I try to send ping with this command ping -s 500 192.168.1.127 ping is successfull, but when I try to send this ping -s 580 192.168.1.8 ping reply didnt accept from computer but my 192.168.1.127 device send reply I see on network analyser. But computer not accept 500+ data. How can I solve this problem.

When I send the 500+ ping from computer my device replied just one time, and it shows me this error:

Expert Info (Error/Protocol): IPv4 total length exceeds packet length (578 bytes)

enter image description here

and I have bad checksum

What is the reason for the this error ? Pc connected point to point to my stm32+lwip device with ethernet interface.

networking – ping returns IPV6 address on ubuntu 20.04

I have installed GitLab on a cloud VM and shortly after stood up a second VM as a postfix server with the same provider (Hetzner)

I first noticed a problem when I went back to the GitLab server to enable SMTP Email and nothing was being sent, not even any logs on the mail server to say a connection was attempted.

I tried to ping the mail server from gitlab and got back only a single response and no further responses not matter how long I wait.

root@gitlab:~# ping mail.simoncarr.co.uk
PING mail.simoncarr.co.uk(2a01:4f8:c2c:a992:: (2a01:4f8:c2c:a992::)) 56 data bytes

As you can see it is an IPV6 response. I don’t remember doing anything other than enabling the ufw that would have impacted networking on gitlab.

I have turned off ufw on gitlab and the mail server, and get the same behaviour.

If I ping an external server I still get an IPV6 response, but I do at least get multiple responses.

root@gitlab:~# ping bbc.co.uk
PING bbc.co.uk(2a04:4e42:600::81 (2a04:4e42:600::81)) 56 data bytes
64 bytes from 2a04:4e42:600::81 (2a04:4e42:600::81): icmp_seq=1 ttl=58 time=3.68 ms
64 bytes from 2a04:4e42:600::81 (2a04:4e42:600::81): icmp_seq=2 ttl=58 time=3.47 ms
64 bytes from 2a04:4e42:600::81 (2a04:4e42:600::81): icmp_seq=3 ttl=58 time=3.52 ms
64 bytes from 2a04:4e42:600::81 (2a04:4e42:600::81): icmp_seq=4 ttl=58 time=3.50 ms
64 bytes from 2a04:4e42:600::81 (2a04:4e42:600::81): icmp_seq=5 ttl=58 time=3.49 ms

If I ping the gitlab server, I get IPV4 response and they are repeated as you would expect.

PING gitlab.simoncarr.co.uk (168.119.124.76) 56(84) bytes of data.
64 bytes from static.76.124.119.168.clients.your-server.de (168.119.124.76): icmp_seq=1 ttl=58 time=0.878 ms
64 bytes from static.76.124.119.168.clients.your-server.de (168.119.124.76): icmp_seq=2 ttl=58 time=0.463 ms
64 bytes from static.76.124.119.168.clients.your-server.de (168.119.124.76): icmp_seq=3 ttl=58 time=0.353 ms
64 bytes from static.76.124.119.168.clients.your-server.de (168.119.124.76): icmp_seq=4 ttl=58 time=0.419 ms

If I ping an external server from the mail server, I again get an IPV6 response.

root@mail:~# ping bbc.co.uk
PING bbc.co.uk(2a04:4e42:600::81 (2a04:4e42:600::81)) 56 data bytes
64 bytes from 2a04:4e42:600::81 (2a04:4e42:600::81): icmp_seq=1 ttl=58 time=6.68 ms
64 bytes from 2a04:4e42:600::81 (2a04:4e42:600::81): icmp_seq=2 ttl=58 time=6.24 ms
64 bytes from 2a04:4e42:600::81 (2a04:4e42:600::81): icmp_seq=3 ttl=58 time=6.23 ms
64 bytes from 2a04:4e42:600::81 (2a04:4e42:600::81): icmp_seq=4 ttl=58 time=6.16 ms

The only thing, that I have changed on the mail server, that is related to networking is to add reverse DNS addresses to both IPV4 and IPV6 addresses.

I want to be able to connect from GitLab server to my mail server to send SMTP email. Even with ufw disabled on both servers, GitLab is not communicating with the mail server. I can’t help but think the issue is related to the behaviour I have described above.

HTTP web traffic to my GitLab server is working fine and my mail server is sending and receiving email fine, from mail clients and other SMTP servers.