scp stalls using ppp/pptp vpn

[fpiergen]

scp on a ppp over pptp VPN is very slow. The transfer keeps stalling. The first 128Kb is fast after that it stalls and restarts....takes about 1/2 hour to transfer 500KB. The connection is over a 56k modem. Related processes ( ppp, pptpd, scp )

Thanks for any suggestions.

[kakariko81280]

How have you configured PPP over the PPTP session?

If you end up with TCP over TCP then the connection can stall because both TCP layers try to do congestion and retransmission management. More details can be found here.

If you can give us more specifics of what you have set up we will be able to give you more definitive information.

Let us know how you get on,

Chris...

[fpiergen]

[root@dev devices]# cat /etc/pptpd.conf
################################################## #############################
# $Id: pptpd.conf,v 1.8 2004/04/28 11:36:07 quozl Exp $
#
# Sample Poptop configuration file /etc/pptpd.conf
#
# Changes are effective when pptpd is restarted.
################################################## #############################
option /etc/ppp/options.pptpd
localip 192.168.1.1
remoteip 192.168.1.2-100

[root@dev devices]# cat /etc/ppp/options.pptpd
name *
lock
mtu 1450
mru 1450
proxyarp
auth
ipcp-accept-local
ipcp-accept-remote
lcp-echo-failure 3
lcp-echo-interval 5
deflate 0

+mschap-v2
mppe required,stateless
ms-dns 192.168.1.1
debug

[root@dev ppp]# cat options
lock

Is this all you need?

[fpiergen]

I did a "ls | xargs cat " on /proc/sys/net/ipv4 which contain

conf
icmp_echo_ignore_all
icmp_echo_ignore_broadcasts
icmp_errors_use_inbound_ifaddr
icmp_ignore_bogus_error_responses
icmp_ratelimit
icmp_ratemask
igmp_max_memberships
igmp_max_msf
inet_peer_gc_maxtime
inet_peer_gc_mintime
inet_peer_maxttl
inet_peer_minttl
inet_peer_threshold
ip_autoconfig
ip_default_ttl
ip_dynaddr
ip_forward
ipfrag_high_thresh
ipfrag_low_thresh
ipfrag_max_dist
ipfrag_secret_interval
ipfrag_time
ip_local_port_range
ip_nonlocal_bind
ip_no_pmtu_disc
neigh
route
tcp_abc
tcp_abort_on_overflow
tcp_adv_win_scale
tcp_app_win
tcp_congestion_control
tcp_dsack
tcp_ecn
tcp_fack
tcp_fin_timeout
tcp_frto
tcp_keepalive_intvl
tcp_keepalive_probes
tcp_keepalive_time
tcp_low_latency
tcp_max_orphans
tcp_max_syn_backlog
tcp_max_tw_buckets
tcp_mem
tcp_moderate_rcvbuf
tcp_no_metrics_save
tcp_orphan_retries
tcp_reordering
tcp_retrans_collapse
tcp_retries1
tcp_retries2
tcp_rfc1337
tcp_rmem
tcp_sack
tcp_stdurg
tcp_synack_retries
tcp_syncookies
tcp_syn_retries
tcp_timestamps
tcp_tso_win_divisor
tcp_tw_recycle
tcp_tw_reuse
tcp_window_scaling
tcp_wmem

values

cat: conf: Is a directory
0
1
0
1
250
6168
20
10
120
10
600
120
65664
0
64
0
0
262144
196608
64
600
30
32768 61000
0
0
cat: neigh: Is a directory
cat: route: Is a directory
1
0
2
31
bic
0
0
0
60
0
75
9
7200
0
32768
1024
180000
98304 131072 196608
1
0
0
3
1
3
15
0
4096 87380 174760
0
0
5
1
5
1
3
0
0
1
4096 16384 131072