udp port 69 (tftp) unreachable

Discussion:

Michael Anburaj

2003-05-07 17:24:41 UTC

Hi,

When I do tftp from my TFTP client (Target board running YAMON) it fails.
The TFTP server is configured on a stand-alone PC running RH Linux 9.

Info. about the protocols on the Host PC:
---------------------------------

[***@localhost root]# lsof -c x -a -i
COMMAND PID USER FD TYPE DEVICE SIZE NODE NAME
xinetd 1757 root 5u IPv4 2205 TCP localhost.localdomain:1025 (LISTEN)
xinetd 1757 root 6u IPv4 2208 UDP *:tftp

Captured using $ tcpdump -n (while tftp client was actively trying)
-----------------------
20:56:40.615815 arp who-has 4.42.102.5 tell 4.42.102.6
20:56:40.615890 arp reply 4.42.102.5 is-at 0:e0:98:9e:84:96
20:56:40.622048 4.42.102.6.1040 > 4.42.102.5.tftp: 20 RRQ "vmlinux.rec" (DF)
20:56:40.622112 4.42.102.5 > 4.42.102.6: icmp: 4.42.102.5 udp port tftp
unreachable [tos 0xc0]
20:56:41.699926 4.42.102.6.1040 > 4.42.102.5.tftp: 20 RRQ "vmlinux.rec" (DF)
20:56:41.700006 4.42.102.5 > 4.42.102.6: icmp: 4.42.102.5 udp port tftp
unreachable [tos 0xc0]

Please tell me why the PC host running tftp server is replying udp port tftp
unreachable?

Could this be firewall issue? The RH linux 9 installation is new & its at
home.

Both hosts.allow and hosts.deny files under /etc
are empty.

Please tell me what other issue this might be or a procedure to debug this
further.

Thanks,
-Mike.

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Venkatesh Krishnamurthi

2003-05-07 18:12:28 UTC

Permalink

Hi,

Do you have the firewall enabled? What does "iptables -L" show?

Venkatesh

Post by Michael Anburaj
Hi,
When I do tftp from my TFTP client (Target board running YAMON) it fails.
The TFTP server is configured on a stand-alone PC running RH Linux 9.
---------------------------------
COMMAND PID USER FD TYPE DEVICE SIZE NODE NAME
xinetd 1757 root 5u IPv4 2205 TCP localhost.localdomain:1025 (LISTEN)
xinetd 1757 root 6u IPv4 2208 UDP *:tftp
Captured using $ tcpdump -n (while tftp client was actively trying)
-----------------------
20:56:40.615815 arp who-has 4.42.102.5 tell 4.42.102.6
20:56:40.615890 arp reply 4.42.102.5 is-at 0:e0:98:9e:84:96
20:56:40.622048 4.42.102.6.1040 > 4.42.102.5.tftp: 20 RRQ "vmlinux.rec" (DF)
20:56:40.622112 4.42.102.5 > 4.42.102.6: icmp: 4.42.102.5 udp port tftp
unreachable [tos 0xc0]
20:56:41.699926 4.42.102.6.1040 > 4.42.102.5.tftp: 20 RRQ "vmlinux.rec" (DF)
20:56:41.700006 4.42.102.5 > 4.42.102.6: icmp: 4.42.102.5 udp port tftp
unreachable [tos 0xc0]
Please tell me why the PC host running tftp server is replying udp port tftp
unreachable?
Could this be firewall issue? The RH linux 9 installation is new & its at
home.
Both hosts.allow and hosts.deny files under /etc
are empty.
Please tell me what other issue this might be or a procedure to debug this
further.
Thanks,
-Mike.
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Michael Anburaj

2003-05-07 19:33:57 UTC

Permalink

Hi Venketesh,

Take a look at this & advice me...

[***@localhost root]# iptables -L
Chain INPUT (policy ACCEPT)
target prot opt source destination
RH-Lokkit-0-50-INPUT all -- anywhere
anywhere

Chain FORWARD (policy ACCEPT)
target prot opt source destination
RH-Lokkit-0-50-INPUT all -- anywhere
anywhere

Chain OUTPUT (policy ACCEPT)
target prot opt source destination

Chain RH-Lokkit-0-50-INPUT (2 references)
target prot opt source destination
ACCEPT udp -- anywhere anywhere
udp spts:bootps:bootpc dpts:bootps:bootpc
ACCEPT udp -- anywhere anywhere
udp spts:bootps:bootpc dpts:bootps:bootpc
ACCEPT all -- anywhere anywhere
REJECT tcp -- anywhere anywhere
tcp dpts:0:1023 flags:SYN,RST,ACK/SYN reject-with
icmp-port-unreachable
REJECT tcp -- anywhere anywhere
tcp dpt:nfs flags:SYN,RST,ACK/SYN reject-with
icmp-port-unreachable
REJECT udp -- anywhere anywhere
udp dpts:0:1023 reject-with icmp-port-unreachable
REJECT udp -- anywhere anywhere
udp dpt:nfs reject-with icmp-port-unreachable
REJECT tcp -- anywhere anywhere
tcp dpts:x11:6009 flags:SYN,RST,ACK/SYN
reject-with icmp-port-unreachable
REJECT tcp -- anywhere anywhere
tcp dpt:xfs flags:SYN,RST,ACK/SYN reject-with
icmp-port-unreachable
[***@localhost root]#

Thanks,
-Mike.

Subject: Re: udp port 69 (tftp) unreachable
Date: Wed, 7 May 2003 11:12:28 -0700 (PDT)
Hi,
Do you have the firewall enabled? What does "iptables -L" show?
Venkatesh

Post by Michael Anburaj
Hi,
When I do tftp from my TFTP client (Target board running YAMON) it

fails.

Post by Michael Anburaj
The TFTP server is configured on a stand-alone PC running RH Linux 9.
---------------------------------
COMMAND PID USER FD TYPE DEVICE SIZE NODE NAME
xinetd 1757 root 5u IPv4 2205 TCP localhost.localdomain:1025 (LISTEN)
xinetd 1757 root 6u IPv4 2208 UDP *:tftp
Captured using $ tcpdump -n (while tftp client was actively trying)
-----------------------
20:56:40.615815 arp who-has 4.42.102.5 tell 4.42.102.6
20:56:40.615890 arp reply 4.42.102.5 is-at 0:e0:98:9e:84:96
20:56:40.622048 4.42.102.6.1040 > 4.42.102.5.tftp: 20 RRQ "vmlinux.rec"

(DF)

Post by Michael Anburaj
20:56:40.622112 4.42.102.5 > 4.42.102.6: icmp: 4.42.102.5 udp port tftp
unreachable [tos 0xc0]
20:56:41.699926 4.42.102.6.1040 > 4.42.102.5.tftp: 20 RRQ "vmlinux.rec"

(DF)

Post by Michael Anburaj
20:56:41.700006 4.42.102.5 > 4.42.102.6: icmp: 4.42.102.5 udp port tftp
unreachable [tos 0xc0]
Please tell me why the PC host running tftp server is replying udp port

tftp

Post by Michael Anburaj
unreachable?
Could this be firewall issue? The RH linux 9 installation is new & its

Post by Michael Anburaj
home.
Both hosts.allow and hosts.deny files under /etc
are empty.
Please tell me what other issue this might be or a procedure to debug

this

Post by Michael Anburaj
further.
Thanks,
-Mike.
_________________________________________________________________
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Michael Schwendt

2003-05-07 20:26:43 UTC

Permalink

Post by Michael Anburaj
Take a look at this & advice me...

This would have been more suitable for shrike-list (the
list for Red Hat Linux 9):

https://listman.redhat.com/mailman/listinfo/shrike-list

The topic has nothing to do with development.
The output of "iptables-save" would be much more readable.

Post by Michael Anburaj
REJECT udp -- anywhere anywhere
udp dpts:0:1023 reject-with icmp-port-unreachable

This is the one you're after. For testing, take it out from
"/etc/sysconfig/iptables".

Post by Michael Anburaj
ACCEPT udp -- anywhere anywhere
udp spts:bootps:bootpc dpts:bootps:bootpc

And run "service iptables restart" to load the change rules.

- --

Michael Schwendt

2003-05-07 20:47:39 UTC

Permalink

Post by Michael Schwendt

Post by Michael Anburaj
REJECT udp -- anywhere anywhere
udp dpts:0:1023 reject-with icmp-port-unreachable

This is the one you're after. For testing, take it out from
"/etc/sysconfig/iptables".

Post by Michael Anburaj
ACCEPT udp -- anywhere anywhere
udp spts:bootps:bootpc dpts:bootps:bootpc

Forget this second proposal. With the source ports set like that, it
probably won't work. Not sure what tftp source port is used by
default.

Post by Michael Schwendt
And run "service iptables restart" to load the change rules.

- --

John

2003-05-07 22:50:57 UTC

Permalink

I already said it could be.
service firewall stop
Or
iptables -F
Or, if you're using the old-fashioned ipchains
ipchains -F

Post by Michael Anburaj
Both hosts.allow and hosts.deny files under /etc
are empty.

Good. I didn't think of that one.

Post by Michael Anburaj
Please tell me what other issue this might be or a procedure to debug this
further.

I'm running out of ideas, and I don't (and won't) run RHL 8.0 or later.

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