ubuntu tftpd-hpa server times out

Question

i'm trying to deploy a TFTP server on an Ubuntu machine to backup switche and router config, but i keep getting a timeout even thought i can see tftp traffic coming in.

i have looked around, many people had this problem but none of the answers worked for me.

here are the steps i followed to install tftpd-hpa

sudo apt install tftpd-hpa
open the config file (/etc/default/tftpd-hpa)and add the create flag, here is my current config

# /etc/default/tftpd-hpa

TFTP_USERNAME="tftp"
TFTP_DIRECTORY="/var/lib/tftpboot"
TFTP_ADDRESS="0.0.0.0:69"
TFTP_OPTIONS="--secure --create -v"
~

change ownership and permission of the tftp directory, i think this is what's causing problems but i'm not sure

sudo chown -R tftp /var/lib/tftpboot
sudo chmod -R 777 /var/lib/tftpboot

mheni@lap2:~$ ll /var/lib/ | grep tftp
drwxrwxrwx  3 tftp          nogroup       4096 Oct 11 13:50 tftpboot/

i also tried to change ownership to user and group, (tftp:tftp instead of tftp)

create a directory for the router configs

sudo mkdir /var/lib/tftpboot/RT-SLX-1

mheni@lap2:/var/lib/tftpboot/$ ll
total 12
drwxrwxr-x 3 tftp nogroup 4096 Oct 11 14:11 ./
drwxrwxrwx 3 tftp nogroup 4096 Oct 11 13:50 ../
drwxr-x--- 2 root root    4096 Oct 11 14:11 RT-SLX-1/

change ownership and permissions (because it is owned by root when created)

sudo chown -R tftp:nogroup /var/lib/tftpboot/RT-SLX-1/
sudo chmod -R 777 /var/lib/tftpboot/RT-SLX-1/

mheni@lap2:/var/lib/tftpboot$ ll
total 12
drwxrwxrwx  3 tftp nogroup 4096 Oct 11 13:50 ./
drwxr-xr-x 74 root root    4096 Oct 11 13:45 ../
drwxrwxr-x  2 tftp nogroup 4096 Oct 11 14:17 RT-SLX-1/

restart the tftpd-hpa service and check status

sudo service tftpd-hpa restart
mheni@lap2:/var/lib/tftpboot$ sudo service tftpd-hpa status
● tftpd-hpa.service - LSB: HPA's tftp server
   Loaded: loaded (/etc/init.d/tftpd-hpa; bad; vendor preset: enabled)
   Active: active (running) since Fri 2019-10-11 13:49:19 EDT; 30min ago
     Docs: man:systemd-sysv-generator(8)
  Process: 18660 ExecStop=/etc/init.d/tftpd-hpa stop (code=exited, status=0/SUCCESS)
  Process: 18672 ExecStart=/etc/init.d/tftpd-hpa start (code=exited, status=0/SUCCESS)
   CGroup: /system.slice/tftpd-hpa.service
           └─18685 /usr/sbin/in.tftpd --listen --user tftp --address 0.0.0.0:69 --secure --create -v /var/lib/tftpboot

Oct 11 13:49:19 lap2 systemd[1]: Starting LSB: HPA's tftp server...
Oct 11 13:49:19 lap2 tftpd-hpa[18672]:  * Starting HPA's tftpd in.tftpd
Oct 11 13:49:19 lap2 tftpd-hpa[18672]:    ...done.
Oct 11 13:49:19 lap2 systemd[1]: Started LSB: HPA's tftp server.

check if service is listening

mheni@lap2:/var/lib/tftpboot$ sudo netstat -tunlp | grep tftp
udp        0      0 0.0.0.0:69              0.0.0.0:*                           18685/in.tftpd

try to copy running config from the router and listen in the tftp server using tcpdump.

tftp server ==> 10.11.200.211

router ==> 10.11.200.14

############ ROUTER #########################
mheni connected from 10.11.200.211 using ssh on RT-SLX-1
RT-SLX-1# copy running-config tftp://@10.11.200.211/RT-SLX-1/run-cfg-bkp-10.11.2019-1
Error while transferring file over tftp. Reason:Transfer timed out.

RT-SLX-1# copy running-config tftp://@10.11.200.211/RT-SLX-1/run-cfg-bkp-10.11.2019-1
Error while transferring file over tftp. Reason:Transfer timed out.

RT-SLX-1#

################### Ubuntu TFTP server ######################
mheni@lap2:/var/lib/tftpboot/RT-SLX-1$ sudo tcpdump src 10.11.200.14
tcpdump: verbose output suppressed, use -v or -vv for full protocol decode
listening on enp0s31f6, link-type EN10MB (Ethernet), capture size 262144 bytes

13:52:30.732859 IP 10.11.200.14.ssh > 10.11.200.211.50486: Flags [P.], seq 3610769485:3610769613, ack 3983111689, win 261, options [nop,nop,TS val 954270862 ecr 3182467340], length 128
13:52:32.813201 IP 10.11.200.14.ssh > 10.11.200.211.50486: Flags [P.], seq 128:192, ack 1, win 261, options [nop,nop,TS val 954272942 ecr 3182493847], length 64
13:52:33.734182 IP 10.11.200.14.ssh > 10.11.200.211.50486: Flags [P.], seq 192:320, ack 65, win 261, options [nop,nop,TS val 954273863 ecr 3182496846], 


13:52:35.293485 IP 10.11.200.14.55517 > 10.11.200.211.tftp:  45 WRQ "RT-SLX-1/run-cfg-bkp-10.11.2019-1" netascii
13:52:40.293114 IP 10.11.200.14.55517 > 10.11.200.211.tftp:  45 WRQ "RT-SLX-1/run-cfg-bkp-10.11.2019-1" netascii
13:52:45.292433 IP 10.11.200.14.55517 > 10.11.200.211.tftp:  45 WRQ "RT-SLX-1/run-cfg-bkp-10.11.2019-1" netascii
13:52:50.291666 IP 10.11.200.14.55517 > 10.11.200.211.tftp:  45 WRQ "RT-SLX-1/run-cfg-bkp-10.11.2019-1" netascii
13:52:55.291001 IP 10.11.200.14.55517 > 10.11.200.211.tftp:  45 WRQ "RT-SLX-1/run-cfg-bkp-10.11.2019-1" netascii

as you can see requests are coming in but nothing is written to the directory :(

any pointers are highly apreciated, thank you.

update: capture traffic in both directions

09:41:02.519086 IP 10.11.200.211.33632 > 10.11.200.14.ssh: Flags [P.], seq 5744:5808, ack 6241, win 287, options [nop,nop,TS val 3513004024 ecr 1284829985], length 64
09:41:02.523556 IP 10.11.200.14.ssh > 10.11.200.211.33632: Flags [P.], seq 6241:6321, ack 5808, win 261, options [nop,nop,TS val 1284837839 ecr 3513004024], length 80
09:41:02.523585 IP 10.11.200.211.33632 > 10.11.200.14.ssh: Flags [.], ack 6321, win 287, options [nop,nop,TS val 3513004029 ecr 1284837839], length 0


09:41:03.951654 IP 10.11.200.14.32990 > 10.11.200.211.tftp:  39 WRQ "RT-SLX-1/run-bkp-10-15-2019" netascii
09:41:08.951074 IP 10.11.200.14.32990 > 10.11.200.211.tftp:  39 WRQ "RT-SLX-1/run-bkp-10-15-2019" netascii
09:41:13.950339 IP 10.11.200.14.32990 > 10.11.200.211.tftp:  39 WRQ "RT-SLX-1/run-bkp-10-15-2019" netascii
09:41:18.949665 IP 10.11.200.14.32990 > 10.11.200.211.tftp:  39 WRQ "RT-SLX-1/run-bkp-10-15-2019" netascii
09:41:23.949051 IP 10.11.200.14.32990 > 10.11.200.211.tftp:  39 WRQ "RT-SLX-1/run-bkp-10-15-2019" netascii


09:41:28.991134 IP 10.11.200.14.ssh > 10.11.200.211.33632: Flags [P.], seq 6321:6449, ack 5808, win 261, options [nop,nop,TS val 1284864311 ecr 3513004029], length 128


09:41:34.180628 ARP, Reply 10.11.200.14 is-at 60:9c:9f:de:d2:01 (oui Unknown), length 46


09:41:42.852212 IP 10.11.200.211.33632 > 10.11.200.14.ssh: Flags [P.], seq 5808:5872, ack 6513, win 296, options [nop,nop,TS val 3513044357 ecr 1284866393], length 64
09:41:42.855651 IP 10.11.200.14.ssh > 10.11.200.211.33632: Flags [P.], seq 6513:6577, ack 5872, win 261, options [nop,nop,TS val 1284878178 ecr 3513044357], length 64
09:41:42.855682 IP 10.11.200.211.33632 > 10.11.200.14.ssh: Flags [.], ack 6577, win 296, options [nop,nop,TS val 3513044361 ecr 1284878178], length 0

instead of `tcpdump src 10.11.200.14` can you display `tcpdump host 10.11.200.14` so we can packet in both ways — EchoMike444, Oct 12 '19 at 01:21
@EchoMike444 updated with tcpdump host, it looks like there is only egress traffic and no responses. — Mheni, Oct 15 '19 at 13:46
Any chance you'ld have some firewall enabled on your ubuntu? — SYN, Oct 15 '19 at 14:54
#update @SYN i thought it was disabled but it was actually enabled and blocked all traffic except for SSH. added a rule to allow port 69 and now it's working. thanks. — Mheni, Oct 15 '19 at 15:08

ubuntu tftpd-hpa server times out

update: capture traffic in both directions

0 Answers0