I am still not able to ping into ubuntu/linux or into my aosp target device without explicitly mentioning -I ppp0 interface. ping -I ppp0 10.0.0.1 / ping -I ppp0 10.0.0.2 works but ping 10.0.0.1 / ping 10.0.0.2 does not work, I have verified the ip route, ip tables, ip addr show as well as ifconfig (both on linux and aosp target). Seems to be all good in it. Any suggestions? On Tue, Sep 10, 2024 at 5:10 PM Devesh Chipade <devesh@xxxxxxxxxxxxx> wrote: > > I have resolved the issue now: > > I have commented out the following in my init.rc file > #service console /system/bin/sh > # class core > # console > # disabled > # user shell > # group shell log readproc > # seclabel u:r:shell:s0 > # setenv HOSTNAME console > # shutdown critical > > The console service was configured to use the same UART serial port > that I was using for the PPP connection. > It would interfere with pppd by resetting or controlling the serial > port, causing the "Modem hangup" issue. > > I have a stable connection now running for the past 60 minutes. There > is a ppp connection established between Ubuntu Machine and my AOSP > Target Device. > I can ping from AOSP target device into the Ubuntu Machine the > following (it works): > ping -I ppp0 10.0.0.1 > (I have to use -I and provide the specific interface to ping even > though the ip route is up to date) > And I cannot ping from Ubuntu to AOSP target. > > Strangely, tcpdump shows that packets are received/sent back and forth > # tcpdump -i ppp0 > tcpdump: verbose output suppressed, use -v[v]... for full protocol decode > listening on ppp0, link-type LINUX_SLL (Linux cooked v1), snapshot > length 262144 bytes > 14:49:17.949046 IP 10.0.0.1 > 10.0.0.2: ICMP echo request, id 552, seq > 618, length 64 > 14:49:18.320546 IP 10.0.0.2 > 10.0.0.1: ICMP echo request, id 15, seq > 34, length 64 > 14:49:18.351262 IP 10.0.0.1 > 10.0.0.2: ICMP echo reply, id 15, seq > 34, length 64 > 14:49:18.972947 IP 10.0.0.1 > 10.0.0.2: ICMP echo request, id 552, seq > 619, length 64 > 14:49:19.321893 IP 10.0.0.2 > 10.0.0.1: ICMP echo request, id 15, seq > 35, length 64 > 14:49:19.353363 IP 10.0.0.1 > 10.0.0.2: ICMP echo reply, id 15, seq > 35, length 64 > 14:49:19.997088 IP 10.0.0.1 > 10.0.0.2: ICMP echo request, id 552, seq > 620, length 64 > 14:49:20.323381 IP 10.0.0.2 > 10.0.0.1: ICMP echo request, id 15, seq > 36, length 64 > 14:49:20.356685 IP 10.0.0.1 > 10.0.0.2: ICMP echo reply, id 15, seq > 36, length 64 > > I am not blocked any more, but it would be good to know if there is a way for: > 1. I would be able to ping from Ubuntu machine as well into the AOSP target > 2. Ideally, ping should work without -I and having to explicitly > mention the interface > (something like just ping 10.0.0.1 should work instead of ping -I ppp0 10.0.0.1 > > Thank you. > > On Tue, Sep 10, 2024 at 4:53 PM Paul Mackerras <paulus@xxxxxxxxxx> wrote: > > > > On Tue, Sep 10, 2024 at 11:30:48AM -0700, Devesh Chipade wrote: > > > In my options file, I have debug and kdebug 7. > > > This is all the logs I could get: > > > > The pppd logs look fine. There is nothing in the kernel (dmesg) log > > that looks relevant (in fact kdebug 7 is mostly useful if you are > > actually debugging the kernel driver; it doesn't really help with > > problems like this). > > > > Do you have logs from pppd on the ubuntu/linux side? Is something > > causing it to terminate? > > > > Alternatively, do you have another service running on either side > > which also thinks it is using the same serial port? Something like a > > getty, or whatever the systemd equivalent is for providing a login > > prompt? You could do "fuser /dev/ttyMSM0" or "fuser /dev/ttyUSB0" as > > root during the 6 seconds when the link is up to check if something > > other than pppd also has the serial port open. > > > > Paul.
