ping provides vague message `Packet filtered'
Affects | Status | Importance | Assigned to | Milestone | |
---|---|---|---|---|---|
iputils (Ubuntu) |
Confirmed
|
Undecided
|
Unassigned |
Bug Description
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affects /distros/
root@edgy:~# ping 172.18.45.41
PING 172.18.45.41 (172.18.45.41) 56(84) bytes of data.
- From 172.18.45.41 icmp_seq=1 Packet filtered
root@samual8:~# tcpdump -x -vvs500 -lnivif16.0
tcpdump: listening on vif16.0, link-type EN10MB (Ethernet), capture size 500 byt
es
12:35:41.462555 arp who-has 172.18.45.41 tell 172.18.45.66
0x0000: 0001 0800 0604 0001 0016 3e7c aa7f ac12
0x0010: 2d42 0000 0000 0000 ac12 2d29
12:35:41.462782 arp reply 172.18.45.41 is-at fe:ff:ff:ff:ff:ff
0x0000: 0001 0800 0604 0002 feff ffff ffff ac12
0x0010: 2d29 0016 3e7c aa7f ac12 2d42
12:35:41.463059 IP (tos 0x0, ttl 64, id 0, offset 0, flags [DF], proto: ICMP (1
), length: 84) 172.18.45.66 > 172.18.45.41: ICMP echo request, id 15627, seq 1,
length 64
0x0000: 4500 0054 0000 4000 4001 8819 ac12 2d42
0x0010: ac12 2d29 0800 d910 3d0b 0001 0d8e d044
0x0020: 120d 0700 0809 0a0b 0c0d 0e0f 1011 1213
0x0030: 1415 1617 1819 1a1b 1c1d 1e1f 2021 2223
0x0040: 2425 2627 2829 2a2b 2c2d 2e2f 3031 3233
0x0050: 3435 3637
12:35:41.463112 IP (tos 0xc0, ttl 64, id 43140, offset 0, flags [none], proto:
ICMP (1), length: 112) 172.18.45.41 > 172.18.45.66: ICMP host 172.18.45.41 unrea
chable - admin prohibited filter, length 92
IP (tos 0x0, ttl 64, id 0, offset 0, flags [DF], proto: ICMP (1), lengt
h: 84) 172.18.45.66 > 172.18.45.41: ICMP echo request, id 15627, seq 1, length 6
4
0x0000: 45c0 0070 a884 0000 4001 1eb9 ac12 2d29
0x0010: ac12 2d42 030d fcf2 0000 0000 4500 0054
0x0020: 0000 4000 4001 8819 ac12 2d42 ac12 2d29
0x0030: 0800 d910 3d0b 0001 0d8e d044 120d 0700
0x0040: 0809 0a0b 0c0d 0e0f 1011 1213 1415 1617
0x0050: 1819 1a1b 1c1d 1e1f 2021 2223 2425 2627
0x0060: 2829 2a2b 2c2d 2e2f 3031 3233 3435 3637
4 packets captured
8 packets received by filter
0 packets dropped by kernel
root@samual8:~#
I note that even tcpdump has been contaminated with the imprecise term
`filter' and it has also inaccurately described the message as `host
unreachable' when in fact it's `Destination Unreachable' (type 3) code
13 `Communication Administratively Prohibited' which doesn't specify
`host' as opposed to `network'.
ping should say something precise and accurate, such as
ICMP dest unreach - comm admin prohib
If you really must say `packet filtered' for the benefit of
ignoramuses, you could say
ICMP dest unreach - comm admin prohib (Packet filtered)
for code 13.
This message would go along with
ICMP dest unreach - net admin prohib (Packet filtered)
ICMP dest unreach - host admin prohib (Packet filtered)
for ICMP codes 9 and 10 respectively.
References:
ICMP type 3 (destination unreachable): RFC792 page 3.
ICMP dest unreach codes 9 and 10: RFC1122 s3.2.2.1.
ICMP dest unreach code 13: RFC1812 s5.2.7.1.
I will be reporting a separate bug about the inaccurate output from
tcpdump.
Ian.
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Thank you for this remark.
Changing state from new to Confirmed, as there is enough info to let developer decide what to do next.