Re: [Dorset] Network connectivity issues
** Tim [2019-01-13 16:39]: > On 13/01/2019 14:47, t...@ls83.eclipse.co.uk wrote: > > Hi Ralph > > > > On 13/01/19 11:31, Ralph Corderoy wrote: > > > Hi Tim, > > > > > > I'll just ask lots of questions in the hope it strikes lucky. > > > > > > > I have a puzzling issue here, in that I can't see a laptop on my > > > > network from my own computer (normally I can ssh into the laptop just > > > > fine). Both are connected via Wifi. The laptop has a static IP. > > > > > > So both Computer and Laptop are *only* connected by Wi-fi. > > > > Yes. > > > > Computer's > > > IP address is from the router's DHCP server. The Laptop's IP address is > > > static. Is that last one done by having the DHCP server always dish out > > > the same IP address for Laptop's MAC address, or the Laptop has it > > > configured directly? If the latter, does the DHCP server know to steer > > > clear of the static addresses when allocating dynamically? > > > > > IP addresses are from third machine (server), which is running dhcpd > > dishing out addresses to Laptop and Computer. Laptop gets same IP > > address 192.168.2.8 from its MAC address, Computer gets its from a pool, > > 192.168.2.205. The DHCP server pool is well clear of the static IP's. > > > > > Can Laptop see Computer, e.g. ping(1), when Computer can't see Laptop? > > > > > No. > > > > > All devices are on the same IP network, including the network mask? > > > > > > > Yes. > > > > > > However, I can ssh into a third computer on the network > > > > > > How is Third connected? Also Wi-fi only? Static or dynamic IP address? > > > > Cabled, static IP 192.168.2.2. > > > > > > and from there can ping (and ssh into) the laptop. > > > > > > When Computer SSH's into Third, does w(1) show you've come from the > > > Computer IP address you expect? Does `arp' show Computer's MAC address > > > or that of an access point? > > > > w(1) shows 192.168.2.205 as expected. > > > > arp shows the MAC address of Computer, not an access point. > > > > > > > > Can Laptop SSH into Third? Ditto above WRT w(1). > > > > > > > Haven't got SSH set up for SSH logins from Laptop to Third, although I > > expect it to work as these machines can see each other on the network. > > > > > > arp lists the laptop HWaddess as incomplete. > > > > > > There's also ip-neighbour(8) that gives `ip neigh' to show the table, > > > and allows an entry to be added. When it's not working, you could try > > > explicitly adding an ARP table entry to Computer for Laptop and see if > > > that makes it work. > > > > OK, tried > > > > #ip neigh add 192.168.2.8 lladdr 00:24:d2:94:35:16 dev wlp1s0 > > RTNETLINK answers: File exists > > > > > > Further tests: > > > > Disconnecting both Computer and Laptop from the access point and then > > reconnecting both to a different access point. Now Computer cannot see > > Laptop /or/ Third computer. So disconnect Computer again and get > > physically close to the access point. Reconnect and now can see both. > > > > Repeat with original access point, ensuring in close proximity. Again > > can now see Laptop and Third from Computer. > > > > So looks like a poor Wifi signal on original connect may be a factor. > > > > I have seen something similar previously in terms of getting an IP > > address from the DHCP server. I appear to be connected to the network > > but have no IP address assigned to Computer. I am using Network Manager > > of XFCE and suspect that under weak Wifi conditions I'm only getting a > > partial connection. > > I have seen with some WiFi access point the have the "the lights are on but > nobody is an home" syndrome, they look like they are working (lights etc) > but seemed to get stuck in a loop, you can not talk to them you can not see > them they are either limited in what they do or just don't do it at all. > Turn the power off to them. wait 10 seconds and then turn it back on again > and everything works as normal. Is there a firmware update available for > your access point? ** end quote [Tim] I see that sometimes with my access point. It seems to pass traffic fine on the wired connections, and several existing wireless connections work fine, but new ones and the odd existing one and indicate they are working, but completely fail when it comes to actually using anything on the network. After a while they stop picking up DHCP leases (likely beause my AP doesn't handle that as my config is beyond its capabilities - or was historically). After a while (if I leave it that long) other devices start failing to route traffic too. I have found the same issue with my the Billion BiPAC 7800N, the replacement Netgear WNDR3700, the next replacement TP-Link TL-WDR3600 and the current Netgear WNDR3700 with OpenWRT installed (which is actually much better, but still not perfect). The Netgear was aimed at improving performance, but was replaced because there were two features on it that I needed that couldn't be used at the same time (from
Re: [Dorset] Network connectivity issues
Hi Ralph On 13/01/19 16:58, Ralph Corderoy wrote: #ip neigh add 192.168.2.8 lladdr 00:24:d2:94:35:16 dev wlp1s0 RTNETLINK answers: File exists That suggests there was an (incomplete?) entry already and either `replace' or `change' should be used. Yes, looks like something to do with arp tables, maybe tied in with clients moving from access point to access point. One access point is a router, and the others are connected to Ethernet sockets on that router. I'll do further tests. Cheers Tim -- Next meeting: BEC, Bournemouth, Tuesday, 2019-02-05 20:00 Check to whom you are replying Meetings, mailing list, IRC, ... http://dorset.lug.org.uk/ New thread, don't hijack: mailto:dorset@mailman.lug.org.uk
Re: [Dorset] Network connectivity issues
Hi Tim, > > Can Laptop SSH into Third? Ditto above WRT w(1). > > Haven't got SSH set up for SSH logins from Laptop to Third, although I > expect it to work as these machines can see each other on the network. All you really need is a TCP server that gives a known response so you can see the handshake worked and data was transferred; more work than the DHCP that succeeds. SSH transfers quite a bit back and forth before you're logged in, but a simple server can be created. $ cat >mark #! /bin/sh hostname date $ chmod +x mark Then to run it, listening on all interfaces on TCP port 12345, and running that script on every connection: $ socat tcp4-listen:12345,reuseaddr,fork exec:./mark Use your client of choice to connect, e.g. telnet(1). $ nc 127.1 12345 orac 2019-01-13 16:51:25 + Sun ^D $ $ nc 127.1 12345 orac 2019-01-13 16:52:05 + Sun ^D > OK, tried > > #ip neigh add 192.168.2.8 lladdr 00:24:d2:94:35:16 dev wlp1s0 > RTNETLINK answers: File exists That suggests there was an (incomplete?) entry already and either `replace' or `change' should be used. > So looks like a poor Wifi signal on original connect may be a factor. https://wiki.archlinux.org/index.php/Wifi says signal strength, without a GUI queering the pitch, can be seen with `iw dev interface station dump'. Perhaps there's a new source of occasional interference? Cheers, Ralph. -- Next meeting: BEC, Bournemouth, Tuesday, 2019-02-05 20:00 Check to whom you are replying Meetings, mailing list, IRC, ... http://dorset.lug.org.uk/ New thread, don't hijack: mailto:dorset@mailman.lug.org.uk
Re: [Dorset] Network connectivity issues
On 13/01/2019 14:47, t...@ls83.eclipse.co.uk wrote: Hi Ralph On 13/01/19 11:31, Ralph Corderoy wrote: Hi Tim, I'll just ask lots of questions in the hope it strikes lucky. I have a puzzling issue here, in that I can't see a laptop on my network from my own computer (normally I can ssh into the laptop just fine). Both are connected via Wifi. The laptop has a static IP. So both Computer and Laptop are *only* connected by Wi-fi. Yes. Computer's IP address is from the router's DHCP server. The Laptop's IP address is static. Is that last one done by having the DHCP server always dish out the same IP address for Laptop's MAC address, or the Laptop has it configured directly? If the latter, does the DHCP server know to steer clear of the static addresses when allocating dynamically? IP addresses are from third machine (server), which is running dhcpd dishing out addresses to Laptop and Computer. Laptop gets same IP address 192.168.2.8 from its MAC address, Computer gets its from a pool, 192.168.2.205. The DHCP server pool is well clear of the static IP's. Can Laptop see Computer, e.g. ping(1), when Computer can't see Laptop? No. All devices are on the same IP network, including the network mask? Yes. However, I can ssh into a third computer on the network How is Third connected? Also Wi-fi only? Static or dynamic IP address? Cabled, static IP 192.168.2.2. and from there can ping (and ssh into) the laptop. When Computer SSH's into Third, does w(1) show you've come from the Computer IP address you expect? Does `arp' show Computer's MAC address or that of an access point? w(1) shows 192.168.2.205 as expected. arp shows the MAC address of Computer, not an access point. Can Laptop SSH into Third? Ditto above WRT w(1). Haven't got SSH set up for SSH logins from Laptop to Third, although I expect it to work as these machines can see each other on the network. arp lists the laptop HWaddess as incomplete. There's also ip-neighbour(8) that gives `ip neigh' to show the table, and allows an entry to be added. When it's not working, you could try explicitly adding an ARP table entry to Computer for Laptop and see if that makes it work. OK, tried #ip neigh add 192.168.2.8 lladdr 00:24:d2:94:35:16 dev wlp1s0 RTNETLINK answers: File exists Further tests: Disconnecting both Computer and Laptop from the access point and then reconnecting both to a different access point. Now Computer cannot see Laptop /or/ Third computer. So disconnect Computer again and get physically close to the access point. Reconnect and now can see both. Repeat with original access point, ensuring in close proximity. Again can now see Laptop and Third from Computer. So looks like a poor Wifi signal on original connect may be a factor. I have seen something similar previously in terms of getting an IP address from the DHCP server. I appear to be connected to the network but have no IP address assigned to Computer. I am using Network Manager of XFCE and suspect that under weak Wifi conditions I'm only getting a partial connection. Cheers Tim -- Next meeting: BEC, Bournemouth, Tuesday, 2019-02-05 20:00 Check to whom you are replying Meetings, mailing list, IRC, ... http://dorset.lug.org.uk/ New thread, don't hijack: mailto:dorset@mailman.lug.org.uk I have seen with some WiFi access point the have the "the lights are on but nobody is an home" syndrome, they look like they are working (lights etc) but seemed to get stuck in a loop, you can not talk to them you can not see them they are either limited in what they do or just don't do it at all. Turn the power off to them. wait 10 seconds and then turn it back on again and everything works as normal. Is there a firmware update available for your access point? Tim H -- Next meeting: BEC, Bournemouth, Tuesday, 2019-02-05 20:00 Check to whom you are replying Meetings, mailing list, IRC, ... http://dorset.lug.org.uk/ New thread, don't hijack: mailto:dorset@mailman.lug.org.uk
Re: [Dorset] Network connectivity issues
AP isolation active ??? : https://www.linksys.com/gb/support-article?articleNum=135098 On 13/01/2019 14:47, t...@ls83.eclipse.co.uk wrote: Hi Ralph On 13/01/19 11:31, Ralph Corderoy wrote: Hi Tim, I'll just ask lots of questions in the hope it strikes lucky. I have a puzzling issue here, in that I can't see a laptop on my network from my own computer (normally I can ssh into the laptop just fine). Both are connected via Wifi. The laptop has a static IP. So both Computer and Laptop are *only* connected by Wi-fi. Yes. Computer's IP address is from the router's DHCP server. The Laptop's IP address is static. Is that last one done by having the DHCP server always dish out the same IP address for Laptop's MAC address, or the Laptop has it configured directly? If the latter, does the DHCP server know to steer clear of the static addresses when allocating dynamically? IP addresses are from third machine (server), which is running dhcpd dishing out addresses to Laptop and Computer. Laptop gets same IP address 192.168.2.8 from its MAC address, Computer gets its from a pool, 192.168.2.205. The DHCP server pool is well clear of the static IP's. Can Laptop see Computer, e.g. ping(1), when Computer can't see Laptop? No. All devices are on the same IP network, including the network mask? Yes. However, I can ssh into a third computer on the network How is Third connected? Also Wi-fi only? Static or dynamic IP address? Cabled, static IP 192.168.2.2. and from there can ping (and ssh into) the laptop. When Computer SSH's into Third, does w(1) show you've come from the Computer IP address you expect? Does `arp' show Computer's MAC address or that of an access point? w(1) shows 192.168.2.205 as expected. arp shows the MAC address of Computer, not an access point. Can Laptop SSH into Third? Ditto above WRT w(1). Haven't got SSH set up for SSH logins from Laptop to Third, although I expect it to work as these machines can see each other on the network. arp lists the laptop HWaddess as incomplete. There's also ip-neighbour(8) that gives `ip neigh' to show the table, and allows an entry to be added. When it's not working, you could try explicitly adding an ARP table entry to Computer for Laptop and see if that makes it work. OK, tried #ip neigh add 192.168.2.8 lladdr 00:24:d2:94:35:16 dev wlp1s0 RTNETLINK answers: File exists Further tests: Disconnecting both Computer and Laptop from the access point and then reconnecting both to a different access point. Now Computer cannot see Laptop /or/ Third computer. So disconnect Computer again and get physically close to the access point. Reconnect and now can see both. Repeat with original access point, ensuring in close proximity. Again can now see Laptop and Third from Computer. So looks like a poor Wifi signal on original connect may be a factor. I have seen something similar previously in terms of getting an IP address from the DHCP server. I appear to be connected to the network but have no IP address assigned to Computer. I am using Network Manager of XFCE and suspect that under weak Wifi conditions I'm only getting a partial connection. Cheers Tim -- Next meeting: BEC, Bournemouth, Tuesday, 2019-02-05 20:00 Check to whom you are replying Meetings, mailing list, IRC, ... http://dorset.lug.org.uk/ New thread, don't hijack: mailto:dorset@mailman.lug.org.uk -- Next meeting: BEC, Bournemouth, Tuesday, 2019-02-05 20:00 Check to whom you are replying Meetings, mailing list, IRC, ... http://dorset.lug.org.uk/ New thread, don't hijack: mailto:dorset@mailman.lug.org.uk
Re: [Dorset] Network connectivity issues
Hi Ralph On 13/01/19 11:31, Ralph Corderoy wrote: Hi Tim, I'll just ask lots of questions in the hope it strikes lucky. I have a puzzling issue here, in that I can't see a laptop on my network from my own computer (normally I can ssh into the laptop just fine). Both are connected via Wifi. The laptop has a static IP. So both Computer and Laptop are *only* connected by Wi-fi. Yes. Computer's IP address is from the router's DHCP server. The Laptop's IP address is static. Is that last one done by having the DHCP server always dish out the same IP address for Laptop's MAC address, or the Laptop has it configured directly? If the latter, does the DHCP server know to steer clear of the static addresses when allocating dynamically? IP addresses are from third machine (server), which is running dhcpd dishing out addresses to Laptop and Computer. Laptop gets same IP address 192.168.2.8 from its MAC address, Computer gets its from a pool, 192.168.2.205. The DHCP server pool is well clear of the static IP's. Can Laptop see Computer, e.g. ping(1), when Computer can't see Laptop? No. All devices are on the same IP network, including the network mask? Yes. However, I can ssh into a third computer on the network How is Third connected? Also Wi-fi only? Static or dynamic IP address? Cabled, static IP 192.168.2.2. and from there can ping (and ssh into) the laptop. When Computer SSH's into Third, does w(1) show you've come from the Computer IP address you expect? Does `arp' show Computer's MAC address or that of an access point? w(1) shows 192.168.2.205 as expected. arp shows the MAC address of Computer, not an access point. Can Laptop SSH into Third? Ditto above WRT w(1). Haven't got SSH set up for SSH logins from Laptop to Third, although I expect it to work as these machines can see each other on the network. arp lists the laptop HWaddess as incomplete. There's also ip-neighbour(8) that gives `ip neigh' to show the table, and allows an entry to be added. When it's not working, you could try explicitly adding an ARP table entry to Computer for Laptop and see if that makes it work. OK, tried #ip neigh add 192.168.2.8 lladdr 00:24:d2:94:35:16 dev wlp1s0 RTNETLINK answers: File exists Further tests: Disconnecting both Computer and Laptop from the access point and then reconnecting both to a different access point. Now Computer cannot see Laptop /or/ Third computer. So disconnect Computer again and get physically close to the access point. Reconnect and now can see both. Repeat with original access point, ensuring in close proximity. Again can now see Laptop and Third from Computer. So looks like a poor Wifi signal on original connect may be a factor. I have seen something similar previously in terms of getting an IP address from the DHCP server. I appear to be connected to the network but have no IP address assigned to Computer. I am using Network Manager of XFCE and suspect that under weak Wifi conditions I'm only getting a partial connection. Cheers Tim -- Next meeting: BEC, Bournemouth, Tuesday, 2019-02-05 20:00 Check to whom you are replying Meetings, mailing list, IRC, ... http://dorset.lug.org.uk/ New thread, don't hijack: mailto:dorset@mailman.lug.org.uk
Re: [Dorset] Network connectivity issues
Hi Tim, I'll just ask lots of questions in the hope it strikes lucky. > I have a puzzling issue here, in that I can't see a laptop on my > network from my own computer (normally I can ssh into the laptop just > fine). Both are connected via Wifi. The laptop has a static IP. So both Computer and Laptop are *only* connected by Wi-fi. Computer's IP address is from the router's DHCP server. The Laptop's IP address is static. Is that last one done by having the DHCP server always dish out the same IP address for Laptop's MAC address, or the Laptop has it configured directly? If the latter, does the DHCP server know to steer clear of the static addresses when allocating dynamically? Can Laptop see Computer, e.g. ping(1), when Computer can't see Laptop? All devices are on the same IP network, including the network mask? > However, I can ssh into a third computer on the network How is Third connected? Also Wi-fi only? Static or dynamic IP address? > and from there can ping (and ssh into) the laptop. When Computer SSH's into Third, does w(1) show you've come from the Computer IP address you expect? Does `arp' show Computer's MAC address or that of an access point? Can Laptop SSH into Third? Ditto above WRT w(1). > arp lists the laptop HWaddess as incomplete. There's also ip-neighbour(8) that gives `ip neigh' to show the table, and allows an entry to be added. When it's not working, you could try explicitly adding an ARP table entry to Computer for Laptop and see if that makes it work. > I am periodically seeing issues of this kind, and would like to try to > figure out what's going on. `sudo -i tcpdump -i ens35 -n arp', substituting the appropriate network interface, lets one watch ARP traffic and can be run on multiple machines at once. Cheers, Ralph. -- Next meeting: BEC, Bournemouth, Tuesday, 2019-02-05 20:00 Check to whom you are replying Meetings, mailing list, IRC, ... http://dorset.lug.org.uk/ New thread, don't hijack: mailto:dorset@mailman.lug.org.uk
Re: [Dorset] Network connectivity issues
Hi Keith On 13/01/19 07:56, Keith Edmunds wrote: On Sat, 12 Jan 2019 19:56:35 +, t...@ls83.eclipse.co.uk said: I can't see a laptop on my network from my own computer What exact commands are you typing, and what exactly is the response? tda@ux305ca:~$ ping 192.168.2.8 PING 192.168.2.8 (192.168.2.8): 56 data bytes 92 bytes from ux305ca (192.168.2.205): Destination Host Unreachable 92 bytes from ux305ca (192.168.2.205): Destination Host Unreachable 92 bytes from ux305ca (192.168.2.205): Destination Host Unreachable -- Next meeting at BEC: Bournemouth, Tuesday, 2019-02-05 20:00 Check if you're replying to the list or the author Meetings, mailing list, IRC, ... http://dorset.lug.org.uk/ New thread, don't hijack: mailto:dorset@mailman.lug.org.uk
Re: [Dorset] Network connectivity issues
On Sat, 12 Jan 2019 19:56:35 +, t...@ls83.eclipse.co.uk said: > I can't see a laptop on my network from my own computer What exact commands are you typing, and what exactly is the response? -- Linux Tips: https://www.tiger-computing.co.uk/category/techtips/ -- Next meeting at BEC: Bournemouth, Tuesday, 2019-02-05 20:00 Check if you're replying to the list or the author Meetings, mailing list, IRC, ... http://dorset.lug.org.uk/ New thread, don't hijack: mailto:dorset@mailman.lug.org.uk
Re: [Dorset] Network connectivity issues
On 12/01/2019 19:56, t...@ls83.eclipse.co.uk wrote: Hi I have a puzzling issue here, in that I can't see a laptop on my network from my own computer (normally I can ssh into the laptop just fine). Both are connected via Wifi. The laptop has a static IP. However, I can ssh into a third computer on the network and from there can ping (and ssh into) the laptop. The Wifi network has a total of three access points and whether the laptop and my computer are connected to the same or different access points makes no difference. All three machines running Debian 9. So far I have restarted Network manager on my machine. arp lists the laptop HWaddess as incomplete. I am periodically seeing issues of this kind, and would like to try to figure out what's going on. Cheers Tim -- At the moment my favorite tool for looking at this kind of problem is fing on my android tablet. Peter -- Next meeting at BEC: Bournemouth, Tuesday, 2019-02-05 20:00 Check if you're replying to the list or the author Meetings, mailing list, IRC, ... http://dorset.lug.org.uk/ New thread, don't hijack: mailto:dorset@mailman.lug.org.uk
[Dorset] Network connectivity issues
Hi I have a puzzling issue here, in that I can't see a laptop on my network from my own computer (normally I can ssh into the laptop just fine). Both are connected via Wifi. The laptop has a static IP. However, I can ssh into a third computer on the network and from there can ping (and ssh into) the laptop. The Wifi network has a total of three access points and whether the laptop and my computer are connected to the same or different access points makes no difference. All three machines running Debian 9. So far I have restarted Network manager on my machine. arp lists the laptop HWaddess as incomplete. I am periodically seeing issues of this kind, and would like to try to figure out what's going on. Cheers Tim -- Next meeting at BEC: Bournemouth, Tuesday, 2019-02-05 20:00 Check if you're replying to the list or the author Meetings, mailing list, IRC, ... http://dorset.lug.org.uk/ New thread, don't hijack: mailto:dorset@mailman.lug.org.uk
